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Chapter 5 Cell Transport

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PowerPoint Lectures Campbell Biology: Concepts & Connections, Eighth Edition REECE • TAYLOR • SIMON • DICKEY • HOGAN Chapter 5 Lecture by Edward J. Zalisko The Working Cell © 2015 Pearson Education, Inc.
Transcript
Page 1: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

PowerPoint LecturesCampbell Biology Concepts amp Connections Eighth EditionREECE bull TAYLOR bull SIMON bull DICKEY bull HOGAN

Chapter 5

Lecture by Edward J Zalisko

The Working Cell

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Introduction

bull The plasma membrane and its proteins enable cells to

bull survive andbull function

bull Aquaporins are membrane proteins that function as water channels

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Introduction

bull This chapter addresses how working cells usebull membranesbull energy and bull enzymes

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Figure 50-1

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Figure 50-2 Chapter 5 Big Ideas

Membrane Structureand Function

Energy and the Cell

How Enzymes Function

Cellular respiration

ATPATP

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MEMBRANE STRUCTURE AND FUNCTION

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51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lipids and proteins with many functions

bull Biologists use the fluid mosaic model to describe a membranersquos structure a patchwork of diverse protein molecules embedded in a phospholipid bilayer

bull The plasma membrane exhibits selective permeability

bull The proteins embedded in a membranersquos phospholipid bilayer perform various functions

copy 2015 Pearson Education Inc

Animation Overview of Cell Signaling

>

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Animation Signal Transduction Pathways

>

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Figure 51

Phospholipid

Cholesterol

Membraneproteins

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

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Figure 51-1

Enzyme

Enzyme

O2CO2

Diffusion of smallnonpolar molecules

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

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Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

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Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

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Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

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Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

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Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

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52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

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Figure 52

Water-filledbubble made ofphospholipids

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53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

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Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

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Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

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53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

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Animation Diffusion

>

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Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

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Animation Osmosis

>

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54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

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Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

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55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

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55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

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Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

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Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

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55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

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55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

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Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

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Video Turgid Elodea

>

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Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

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56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

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Figure 56

Solutemolecule

Transportprotein

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56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

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56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

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57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

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Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

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58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

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Animation Active Transport

>

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Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

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Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

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Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

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59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

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59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

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Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

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Animation Receptor-Mediated Endocytosis

>

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Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

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Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

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510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

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510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

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510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

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Animation Energy Concepts

>

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510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

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510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

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510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

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Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

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Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

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Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

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511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

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511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

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Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

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511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

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Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

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511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

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511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

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511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

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Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

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Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

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Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

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Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

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Animation How Enzymes Work

>

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Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

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Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

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514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

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514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

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Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

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514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

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514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

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Figure 516

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

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You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

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You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

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You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

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Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

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Figure 5UN03

bc

a

d

f

e

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Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 2: Chapter 5 Cell Transport

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Introduction

bull The plasma membrane and its proteins enable cells to

bull survive andbull function

bull Aquaporins are membrane proteins that function as water channels

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Introduction

bull This chapter addresses how working cells usebull membranesbull energy and bull enzymes

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Figure 50-1

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Figure 50-2 Chapter 5 Big Ideas

Membrane Structureand Function

Energy and the Cell

How Enzymes Function

Cellular respiration

ATPATP

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MEMBRANE STRUCTURE AND FUNCTION

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51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lipids and proteins with many functions

bull Biologists use the fluid mosaic model to describe a membranersquos structure a patchwork of diverse protein molecules embedded in a phospholipid bilayer

bull The plasma membrane exhibits selective permeability

bull The proteins embedded in a membranersquos phospholipid bilayer perform various functions

copy 2015 Pearson Education Inc

Animation Overview of Cell Signaling

>

copy 2015 Pearson Education Inc

Animation Signal Transduction Pathways

>

copy 2015 Pearson Education Inc

Figure 51

Phospholipid

Cholesterol

Membraneproteins

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

copy 2015 Pearson Education Inc

Figure 51-1

Enzyme

Enzyme

O2CO2

Diffusion of smallnonpolar molecules

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

copy 2015 Pearson Education Inc

Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

copy 2015 Pearson Education Inc

Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

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Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

copy 2015 Pearson Education Inc

Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

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Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

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Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

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53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

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Animation Diffusion

>

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Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

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Animation Osmosis

>

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54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

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55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

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55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

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Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

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Video Turgid Elodea

>

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Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

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Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

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Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

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59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

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Animation Receptor-Mediated Endocytosis

>

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Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 3: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Introduction

bull This chapter addresses how working cells usebull membranesbull energy and bull enzymes

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Figure 50-1

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Figure 50-2 Chapter 5 Big Ideas

Membrane Structureand Function

Energy and the Cell

How Enzymes Function

Cellular respiration

ATPATP

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MEMBRANE STRUCTURE AND FUNCTION

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51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lipids and proteins with many functions

bull Biologists use the fluid mosaic model to describe a membranersquos structure a patchwork of diverse protein molecules embedded in a phospholipid bilayer

bull The plasma membrane exhibits selective permeability

bull The proteins embedded in a membranersquos phospholipid bilayer perform various functions

copy 2015 Pearson Education Inc

Animation Overview of Cell Signaling

>

copy 2015 Pearson Education Inc

Animation Signal Transduction Pathways

>

copy 2015 Pearson Education Inc

Figure 51

Phospholipid

Cholesterol

Membraneproteins

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

copy 2015 Pearson Education Inc

Figure 51-1

Enzyme

Enzyme

O2CO2

Diffusion of smallnonpolar molecules

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

copy 2015 Pearson Education Inc

Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

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Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

copy 2015 Pearson Education Inc

Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

copy 2015 Pearson Education Inc

Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

copy 2015 Pearson Education Inc

Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

copy 2015 Pearson Education Inc

Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

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Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

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Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

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Animation Osmosis

>

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54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

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55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

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Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

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Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

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Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

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59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

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Animation Receptor-Mediated Endocytosis

>

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Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 4: Chapter 5 Cell Transport

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Figure 50-1

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Figure 50-2 Chapter 5 Big Ideas

Membrane Structureand Function

Energy and the Cell

How Enzymes Function

Cellular respiration

ATPATP

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MEMBRANE STRUCTURE AND FUNCTION

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51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lipids and proteins with many functions

bull Biologists use the fluid mosaic model to describe a membranersquos structure a patchwork of diverse protein molecules embedded in a phospholipid bilayer

bull The plasma membrane exhibits selective permeability

bull The proteins embedded in a membranersquos phospholipid bilayer perform various functions

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Animation Overview of Cell Signaling

>

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Animation Signal Transduction Pathways

>

copy 2015 Pearson Education Inc

Figure 51

Phospholipid

Cholesterol

Membraneproteins

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

copy 2015 Pearson Education Inc

Figure 51-1

Enzyme

Enzyme

O2CO2

Diffusion of smallnonpolar molecules

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

copy 2015 Pearson Education Inc

Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

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Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

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Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

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Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

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Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

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52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

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Figure 52

Water-filledbubble made ofphospholipids

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53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

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Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

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Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

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53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

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Animation Diffusion

>

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Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

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Animation Osmosis

>

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54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

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Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

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55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

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Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

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Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

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55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

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55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

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Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

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Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

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Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

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56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

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57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

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Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

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Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

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Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

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59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

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59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

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Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

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Animation Receptor-Mediated Endocytosis

>

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Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

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Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

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510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

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Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

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511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

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511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

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You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

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You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

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Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

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Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

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Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 5: Chapter 5 Cell Transport

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Figure 50-2 Chapter 5 Big Ideas

Membrane Structureand Function

Energy and the Cell

How Enzymes Function

Cellular respiration

ATPATP

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MEMBRANE STRUCTURE AND FUNCTION

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51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lipids and proteins with many functions

bull Biologists use the fluid mosaic model to describe a membranersquos structure a patchwork of diverse protein molecules embedded in a phospholipid bilayer

bull The plasma membrane exhibits selective permeability

bull The proteins embedded in a membranersquos phospholipid bilayer perform various functions

copy 2015 Pearson Education Inc

Animation Overview of Cell Signaling

>

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Animation Signal Transduction Pathways

>

copy 2015 Pearson Education Inc

Figure 51

Phospholipid

Cholesterol

Membraneproteins

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

copy 2015 Pearson Education Inc

Figure 51-1

Enzyme

Enzyme

O2CO2

Diffusion of smallnonpolar molecules

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

copy 2015 Pearson Education Inc

Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

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Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

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Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

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Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

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Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

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52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

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Figure 52

Water-filledbubble made ofphospholipids

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53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

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Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

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Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

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53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

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Animation Diffusion

>

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Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

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Animation Osmosis

>

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54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

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Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

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55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

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55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

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Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

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Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

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55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

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55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

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Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

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Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

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Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

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56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

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57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

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Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

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Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

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59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

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59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

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Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

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Animation Receptor-Mediated Endocytosis

>

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Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

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Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

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510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

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Animation Energy Concepts

>

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510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

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510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

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Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

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511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

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511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

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Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

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You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

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You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

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You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 6: Chapter 5 Cell Transport

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MEMBRANE STRUCTURE AND FUNCTION

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51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lipids and proteins with many functions

bull Biologists use the fluid mosaic model to describe a membranersquos structure a patchwork of diverse protein molecules embedded in a phospholipid bilayer

bull The plasma membrane exhibits selective permeability

bull The proteins embedded in a membranersquos phospholipid bilayer perform various functions

copy 2015 Pearson Education Inc

Animation Overview of Cell Signaling

>

copy 2015 Pearson Education Inc

Animation Signal Transduction Pathways

>

copy 2015 Pearson Education Inc

Figure 51

Phospholipid

Cholesterol

Membraneproteins

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

copy 2015 Pearson Education Inc

Figure 51-1

Enzyme

Enzyme

O2CO2

Diffusion of smallnonpolar molecules

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

copy 2015 Pearson Education Inc

Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

copy 2015 Pearson Education Inc

Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

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Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

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Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

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Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

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Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

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Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

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Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

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53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

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Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

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Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

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55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

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55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

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55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

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Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

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59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

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Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

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Animation Receptor-Mediated Endocytosis

>

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Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

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Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

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Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

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511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

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514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 7: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lipids and proteins with many functions

bull Biologists use the fluid mosaic model to describe a membranersquos structure a patchwork of diverse protein molecules embedded in a phospholipid bilayer

bull The plasma membrane exhibits selective permeability

bull The proteins embedded in a membranersquos phospholipid bilayer perform various functions

copy 2015 Pearson Education Inc

Animation Overview of Cell Signaling

>

copy 2015 Pearson Education Inc

Animation Signal Transduction Pathways

>

copy 2015 Pearson Education Inc

Figure 51

Phospholipid

Cholesterol

Membraneproteins

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

copy 2015 Pearson Education Inc

Figure 51-1

Enzyme

Enzyme

O2CO2

Diffusion of smallnonpolar molecules

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

copy 2015 Pearson Education Inc

Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

copy 2015 Pearson Education Inc

Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

copy 2015 Pearson Education Inc

Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

copy 2015 Pearson Education Inc

Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

copy 2015 Pearson Education Inc

Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

copy 2015 Pearson Education Inc

Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

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514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

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514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

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You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

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You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 8: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation Overview of Cell Signaling

>

copy 2015 Pearson Education Inc

Animation Signal Transduction Pathways

>

copy 2015 Pearson Education Inc

Figure 51

Phospholipid

Cholesterol

Membraneproteins

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

copy 2015 Pearson Education Inc

Figure 51-1

Enzyme

Enzyme

O2CO2

Diffusion of smallnonpolar molecules

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

copy 2015 Pearson Education Inc

Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

copy 2015 Pearson Education Inc

Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

copy 2015 Pearson Education Inc

Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

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Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

copy 2015 Pearson Education Inc

Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

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Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

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Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

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514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

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514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 9: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation Signal Transduction Pathways

>

copy 2015 Pearson Education Inc

Figure 51

Phospholipid

Cholesterol

Membraneproteins

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

copy 2015 Pearson Education Inc

Figure 51-1

Enzyme

Enzyme

O2CO2

Diffusion of smallnonpolar molecules

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

copy 2015 Pearson Education Inc

Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

copy 2015 Pearson Education Inc

Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

copy 2015 Pearson Education Inc

Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

copy 2015 Pearson Education Inc

Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

copy 2015 Pearson Education Inc

Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

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Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

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Animation Osmosis

>

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54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

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Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

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Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

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514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

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514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

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514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

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514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 10: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 51

Phospholipid

Cholesterol

Membraneproteins

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

copy 2015 Pearson Education Inc

Figure 51-1

Enzyme

Enzyme

O2CO2

Diffusion of smallnonpolar molecules

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

copy 2015 Pearson Education Inc

Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

copy 2015 Pearson Education Inc

Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

copy 2015 Pearson Education Inc

Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

copy 2015 Pearson Education Inc

Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

copy 2015 Pearson Education Inc

Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

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Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

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Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

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514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

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514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

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514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

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You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

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You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

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You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 11: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 51-1

Enzyme

Enzyme

O2CO2

Diffusion of smallnonpolar molecules

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

copy 2015 Pearson Education Inc

Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

copy 2015 Pearson Education Inc

Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

copy 2015 Pearson Education Inc

Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

copy 2015 Pearson Education Inc

Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

copy 2015 Pearson Education Inc

Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

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Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

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Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

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Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

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Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

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Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

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514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

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514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

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You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

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You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

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You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 12: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 51-2

Diffusion of smallnonpolar molecules

O2CO2

copy 2015 Pearson Education Inc

Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

copy 2015 Pearson Education Inc

Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

copy 2015 Pearson Education Inc

Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

copy 2015 Pearson Education Inc

Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

copy 2015 Pearson Education Inc

Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

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Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

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Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

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Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

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Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

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Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

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Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

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Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

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514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

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514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

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514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

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514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

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You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

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You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

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You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 13: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 51-3

Solute molecules

Channelprotein

Activetransportprotein

Transport Proteins

ATP

bull Allow specific ions or moleculesto enter or exit the cell

copy 2015 Pearson Education Inc

Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

copy 2015 Pearson Education Inc

Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

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Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

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Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

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Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

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Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

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Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

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Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

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Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

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514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

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514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

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514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

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514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

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You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

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You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

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You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 14: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 51-4

Enzymes

Initialreactant

Product ofreaction

Enzymesbull Some membrane proteins are enzymesbull Enzymes may be grouped to carry out

sequential reactions

copy 2015 Pearson Education Inc

Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

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Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

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Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

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Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

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Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

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Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

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Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

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Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

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Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

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514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

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514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

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514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

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514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

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You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

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You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 15: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 51-5

Extracellularmatrix

Attachmentprotein

Microfilamentsof cytoskeleton

Attachment Proteinsbull Attach to the extracellular matrix and cytoskeletonbull Help support the membranebull Can coordinate external and internal changes

copy 2015 Pearson Education Inc

Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

copy 2015 Pearson Education Inc

Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

copy 2015 Pearson Education Inc

Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

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Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

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Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

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Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

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Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

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Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

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514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

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514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

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514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

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514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

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You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

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You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

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You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

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Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 16: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 51-6

Signalingmolecule

Receptorprotein

Receptor Proteinsbull Signaling molecules bind to receptor proteinsbull Receptor proteins relay the message by

activating other molecules inside the cell

copy 2015 Pearson Education Inc

Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

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Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

copy 2015 Pearson Education Inc

Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

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Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

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Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

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514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

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You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 17: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 51-7

Junctionprotein

Junctionprotein

Junction Proteinsbull Form intercellular junctions that

attach adjacent cells

copy 2015 Pearson Education Inc

Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

copy 2015 Pearson Education Inc

Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

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Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 18: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 51-8

Attachedsugars

Glycoprotein

Protein thatrecognizesneighboringcell

Glycoproteinsbull Serve as ID tagsbull May be recognized by membrane

proteins of other cells

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

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Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

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Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 19: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 51-9

Phospholipid

Cholesterol

Microfilamentsof cytoskeleton

Extracellular sideof membrane

Fibers ofextracellularmatrices (ECM)

Cytoplasmic sideof membrane

O2 CO2

Diffusion of smallnonpolar molecules

Enzyme

Attachmentprotein

Receptorprotein

Channelprotein

Activetransportprotein ATP

Junctionprotein

Glyco-protein

Junctionprotein

Enzyme

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

copy 2015 Pearson Education Inc

Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 20: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

52 EVOLUTION CONNECTION The spontaneous formation of membranes was a critical step in the origin of life

bull Phospholipids the key ingredient of biological membranes spontaneously self-assemble into simple membranes

bull The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the first cells

copy 2015 Pearson Education Inc

Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

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You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

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You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 21: Chapter 5 Cell Transport

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Figure 52

Water-filledbubble made ofphospholipids

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

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Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

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Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 22: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion is the tendency of particles to spread out evenly in an available space

bull Particles move from an area of more concentrated particles to an area where they are less concentrated

bull This means that particles diffuse down their concentration gradient

bull Eventually the particles reach dynamic equilibrium where there is no net change in concentration on either side of the membrane

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 23: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 53a

Molecules of dye

Pores

Membrane

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

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Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 24: Chapter 5 Cell Transport

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Figure 53b

Net diffusion Net diffusion Equilibrium

Net diffusion Net diffusion Equilibrium

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

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Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

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Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 25: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

53 Passive transport is diffusion across a membrane with no energy investment

bull Diffusion across a cell membrane does not require energy so it is called passive transport

bull Diffusion down concentration gradients is the sole means by which oxygen enters your cells and carbon dioxide passes out of cells

copy 2015 Pearson Education Inc

Animation Diffusion

>

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

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Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 26: Chapter 5 Cell Transport

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Animation Diffusion

>

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Animation Membrane Selectivity

>

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54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

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Animation Osmosis

>

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54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

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Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

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55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

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Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

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Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

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55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

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55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

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Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

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Video Turgid Elodea

>

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Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

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56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

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Figure 56

Solutemolecule

Transportprotein

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56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

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56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

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57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

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Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

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Animation Active Transport

>

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Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

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Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

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Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

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59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

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59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

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Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

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Animation Receptor-Mediated Endocytosis

>

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Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

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Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

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510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

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510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

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510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

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Animation Energy Concepts

>

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510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

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510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

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510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

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Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

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Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

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511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

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511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

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511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

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Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

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Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 27: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation Membrane Selectivity

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

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55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

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Video Chlamydomonas

>

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Video Paramecium Vacuole

>

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Video Plasmolysis

>

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Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

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Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

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56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

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Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

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59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

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59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

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Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

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Animation Receptor-Mediated Endocytosis

>

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Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

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Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

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510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

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Animation Energy Concepts

>

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510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

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510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 28: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull One of the most important substances that crosses membranes by passive transport is water

bull The diffusion of water across a selectively permeable membrane is called osmosis

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

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Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

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Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

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59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

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59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

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Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

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Animation Receptor-Mediated Endocytosis

>

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Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

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Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

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510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

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510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

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510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

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Animation Energy Concepts

>

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510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

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510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

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510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

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Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

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511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

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511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

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511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

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Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

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Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 29: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation Osmosis

>

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

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Animation Energy Concepts

>

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510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

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510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

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510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

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Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

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511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

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Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

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Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 30: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

54 Osmosis is the diffusion of water across a membrane

bull If a membrane permeable to water but not to a solute separates two solutions with different concentrations of solute water will cross the membrane moving down its own concentration gradient until the solute concentration on both sides is equal

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

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512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

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HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

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Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

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Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

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Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

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516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 31: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 54

Solutemolecule

Selectivelypermeablemembrane

Watermolecule

Solute moleculewith cluster of water molecules

Osmosis

H2O

Lowerconcentration

of solute

Higherconcentration

of solute

More equalconcentrations

of solute

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 32: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull Tonicity is a term that describes the ability of a surrounding solution to cause a cell to gain or lose water

bull The tonicity of a solution mainly depends on its concentration of solutes relative to the concentration of solutes inside the cell

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 33: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull How will animal cells be affected when placed into solutions of various tonicities

bull In an isotonic solution the concentration of solute is the same on both sides of a membrane and the cell volume will not change

bull In a hypotonic solution the solute concentration is lower outside the cell water molecules move into the cell and the cell will expand and may burst

bull In a hypertonic solution the solute concentration is higher outside the cell water molecules move out of the cell and the cell will shrink

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 34: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Plantcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2O H2O H2O

H2OH2OH2O

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

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55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

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Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 35: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 55

Animalcell

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

H2O

Lysed Normal Shriveled

H2O H2O H2O

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

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Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 36: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull For an animal cell to survive in a hypotonic or hypertonic environment it must engage in osmoregulation the control of water balance

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

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510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

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510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

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511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

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Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 37: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

55 Water balance between cells and their surroundings is crucial to organisms

bull The cell walls of plant cells prokaryotes and fungi make water balance issues somewhat different

bull The cell wall of a plant cell exerts pressure that prevents the cell from taking in too much water and bursting when placed in a hypotonic environment

bull But in a hypertonic environment plant and animal cells both shrivel

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

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513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

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Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

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515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

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Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 38: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Video Chlamydomonas

>

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 39: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Video Paramecium Vacuole

>

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 40: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Video Plasmolysis

>

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

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Animation Exocytosis

>

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Animation Pinocytosis

>

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Animation Phagocytosis

>

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Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

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ENERGY AND THE CELL

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510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 41: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Video Turgid Elodea

>

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 42: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Hypotonic solution(lower solute levels)

Isotonic solution(equal solute levels)

Hypertonic solution(higher solute levels)

Figure 55

Plantcell

Turgid (normal) Flaccid

Plasmamembrane

Shriveled (plasmolyzed)

H2OH2OH2O

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 43: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Hydrophobic substances easily diffuse across a cell membrane

bull However polar or charged substances do not easily cross cell membranes and instead move across membranes with the help of specific transport proteins in a process called facilitated diffusion which

bull does not require energy andbull relies on the concentration gradient

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 44: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 56

Solutemolecule

Transportprotein

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 45: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Some proteins function by becoming a hydrophilic tunnel for passage of ions or other molecules

bull Other proteins bind their passenger change shape and release their passenger on the other side

bull In both cases the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and thus requires no input of energy

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 46: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

56 Transport proteins can facilitate diffusion across membranes

bull Because water is polar its diffusion through a membranersquos hydrophobic interior is relatively slow

bull The very rapid diffusion of water into and out of certain cells is made possible by a protein channel called an aquaporin

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 47: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

57 SCIENTIFIC THINKING Research on another membrane protein led to the discovery of aquaporins

bull Dr Peter Agre received the 2003 Nobel Prize in Chemistry for his discovery of aquaporins

bull His research on the Rh protein used in blood typing led to this discovery

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 48: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 57

Time of rupture

RNA-injected eggs

Control eggs

Time (min)

Rel

ativ

e vo

lum

e of

repr

esen

tativ

e eg

gs

14

0 1 2 3 4 5

13

12

11

10

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 49: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

58 Cells expend energy in the active transport of a solute

bull In active transport a cell must expend energy to move a solute against its concentration gradient

bull The energy molecule ATP supplies the energy for most active transport

bull The following figures show the four main stages of active transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 50: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation Active Transport

>

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 51: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 58-1

Transportprotein

SoluteSolute bindsto transportprotein

1

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 52: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 58-2

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

1 2

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 53: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 58-3

Transportprotein

SoluteATP

Solute bindsto transportprotein

ATP providesenergy forchange inprotein shape

Protein returnsto original shapeand more solutecan bind

1 2 3

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 54: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull A cell uses two mechanisms to move large molecules across membranes

1 Exocytosis is used to export bulky molecules such as proteins or polysaccharides

2 Endocytosis is used to take in large molecules

bull In both cases material to be transported is packaged within a vesicle that fuses with the membrane

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 55: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

59 Exocytosis and endocytosis transport large molecules across membranes

bull There are two kinds of endocytosis1 Phagocytosis is the engulfment of a particle by

the cell wrapping cell membrane around it forming a vacuole

2 Receptor-mediated endocytosis uses membrane receptors for specific solutes The region of the membrane with receptors pinches inward to form a vesiclebull Receptor-mediated endocytosis is used to take in

cholesterol from the blood

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 56: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation Exocytosis and Endocytosis Introduction

>

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 57: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation Exocytosis

>

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 58: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation Pinocytosis

>

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 59: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation Phagocytosis

>

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 60: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation Receptor-Mediated Endocytosis

>

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 61: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 59-0 Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 62: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 59-1

Phagocytosis

Pseudopodium

EXTRACELLULARFLUID

CYTOPLASM

ldquoFoodrdquo orother particle

Foodvacuole

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 63: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 59-2

Receptor-mediated endocytosisCoat protein

Receptor

Specificmolecule

Coatedpit

Coatedvesicle

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 64: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

ENERGY AND THE CELL

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 65: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Cells are miniature chemical factories housing thousands of chemical reactions

bull Some of these chemical reactions release energy and others require energy

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 66: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Energy is the capacity to cause change or to perform work

bull There are two basic forms of energy1 Kinetic energy is the energy of motion2 Potential energy is energy that matter

possesses as a result of its location or structure

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 67: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermal energy is a type of kinetic energy associated with the random movement of atoms or molecules

bull Thermal energy in transfer from one object to another is called heat

bull Light is also a type of kinetic energy it can be harnessed to power photosynthesis

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 68: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Chemical energy is thebull potential energy available for release in a chemical

reaction and bull the most important type of energy for living

organisms to power the work of the cell

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 69: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation Energy Concepts

>

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 70: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Thermodynamics is the study of energy transformations that occur in a collection of matter

bull The word system is used for the matter under study

bull The word surroundings is used for everything outside the system the rest of the universe

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 71: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Two laws govern energy transformations in organisms

bull Per the first law of thermodynamics (also known as the law of energy conservation) energy in the universe is constant

bull Per the second law of thermodynamics energy conversions increase the disorder of the universe

bull Entropy is the measure of disorder or randomness

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 72: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

510 Cells transform energy as they perform work

bull Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work

bull In the car and cells the waste products are carbon dioxide and water

bull Cells use oxygen in reactions that release energy from fuel molecules

bull In cellular respiration the chemical energy stored in organic molecules is used to produce ATP which the cell can use to perform work

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 73: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 510-0

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 74: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 510-1

Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 75: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 510-2

Fuel Energy conversion Waste products

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 76: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Chemical reactions eitherbull release energy (exergonic reactions) orbull require an input of energy and store energy

(endergonic reactions)

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 77: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Exergonic reactions release energybull These reactions release the energy in covalent

bonds of the reactantsbull Burning wood releases the energy in glucose as

heat and lightbull Cellular respiration

bull involves many stepsbull releases energy slowly andbull uses some of the released energy to produce ATP

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 78: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 511a

Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 79: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull An endergonic reactionbull requires an input of energy andbull yields products rich in potential energy

bull Endergonic reactionsbull start with reactant molecules that contain relatively

little potential energy butbull end with products that contain more chemical

energy

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 80: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 511b

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 81: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Photosynthesis is a type of endergonic processbull In photosynthesis

bull energy-poor reactants (carbon dioxide and water) are used

bull energy is absorbed from sunlight andbull energy-rich sugar molecules are produced

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 82: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull A living organism carries out thousands of endergonic and exergonic chemical reactions

bull The total of an organismrsquos chemical reactions is called metabolism

bull A metabolic pathway is a series of chemical reactions that either

bull builds a complex molecule or bull breaks down a complex molecule into simpler

compounds

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 83: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

511 Chemical reactions either release or store energy

bull Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions typically using the energy stored in ATP molecules

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 84: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull ATP adenosine triphosphate powers nearly all forms of cellular work

bull ATP consists ofbull adenosine andbull a triphosphate tail of three phosphate groups

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 85: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation

bull Most cellular work depends on ATP energizing molecules by phosphorylating them

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 86: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 512a-1

Triphosphate

Adenosine P

ATP

P P

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 87: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 512a-2

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 88: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull There are three main types of cellular work1 chemical2 mechanical and3 transport

bull ATP drives all three of these types of work

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 89: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 512bChemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 90: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

512 ATP drives cellular work by coupling exergonic and endergonic reactions

bull A cell uses and regenerates ATP continuouslybull In the ATP cycle energy released in an exergonic

reaction such as the breakdown of glucose during cellular respiration is used in an endergonic reaction to generate ATP from ADP

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 91: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 512c

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 92: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

HOW ENZYMES FUNCTION

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 93: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Although biological molecules possess much potential energy it is not released spontaneously

bull An energy barrier must be overcome before a chemical reaction can begin

bull This energy is called the activation energy (because it activates the reactants)

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 94: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull We can think of activation energy as the amount of energy needed for a reactant molecule to move ldquouphillrdquo to a higher-energy but an unstable state so that the ldquodownhillrdquo part of the reaction can begin

bull One way to speed up a reaction is to add heat which agitates atoms so that bonds break more easily and reactions can proceed but too much heat will kill a cell

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 95: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

513 Enzymes speed up the cellrsquos chemical reactions by lowering energy barriers

bull Enzymesbull function as biological catalystsbull increase the rate of a reaction without being

consumed by the reaction andbull are usually proteins (although some RNA molecules

can function as enzymes)bull Enzymes speed up a reaction by lowering the

activation energy needed for a reaction to begin

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 96: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Animation How Enzymes Work

>

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 97: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 513-0

Reactants

Progress of the reactionProducts

a

b

c

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

Ener

gy

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 98: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 513-1

Reactant

Products

Reactant

Products

Ener

gy

Activationenergybarrier

Without enzyme

Enzyme

Ener

gy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 99: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 513-2

Products

Reactant

Ener

gy

Activationenergybarrier

Without enzyme

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 100: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 513-3

Reactant

Products

EnzymeEn

ergy

Activationenergybarrierreduced byenzyme

With enzyme

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 101: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 513-4

Reactants

Progress of the reactionProducts

ab

cEner

gy

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 102: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull An enzymebull is very selective in the reaction it catalyzes andbull has a shape that determines the enzymersquos

specificity

bull The specific reactant that an enzyme acts on is called the enzymersquos substrate

bull A substrate fits into a region of the enzyme called the active site

bull Enzymes are specific because only specific substrate molecules fit into their active site

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 103: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull The following figure illustrates the catalytic cycle of an enzyme

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 104: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 514-1

Enzyme(sucrase)

Active site

The enzyme availablewith an empty active site

1

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 105: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 514-2

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 106: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 514-3

The substrateis convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 107: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 514-4

Glucose

Fructose

The productsare released The substrate

is convertedto products

H2O

Enzyme(sucrase)

Substratebinds toenzyme withinduced fit

Substrate(sucrose)

Active site

The enzyme availablewith an empty active site

1

2

3

4

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 108: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull For every enzyme there are optimal conditions under which it is most effective

bull Temperature affects molecular motionbull An enzymersquos optimal temperature produces the

highest rate of contact between the reactants and the enzymersquos active site

bull Most human enzymes work best at 35ndash40degCbull The optimal pH for most enzymes is near

neutrality

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 109: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

514 A specific enzyme catalyzes each cellular reaction

bull Many enzymes require nonprotein helpers called cofactors which

bull bind to the active site andbull function in catalysis

bull Some cofactors are inorganic such as the ions of zinc iron or copper

bull If a cofactor is an organic molecule such as most vitamins it is called a coenzyme

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 110: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull A chemical that interferes with an enzymersquos activity is called an inhibitor

bull Competitive inhibitorsbull block substrates from entering the active site andbull reduce an enzymersquos productivity

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 111: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Noncompetitive inhibitorsbull bind to the enzyme somewhere other than the

active site bull change the shape of the active site andbull prevent the substrate from binding

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 112: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 515a

Substrate

Enzyme

Active site

Normal binding of substrate

Competitiveinhibitor

Noncompetitiveinhibitor

Enzyme inhibition

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 113: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

515 Enzyme inhibition can regulate enzyme activity in a cell

bull Enzyme inhibitors are important in regulating cell metabolism

bull In some reactions the product may act as an inhibitor of one of the enzymes in the pathway that produced it This is called feedback inhibition

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 114: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 515b

Feedback inhibition

Enzyme 1

Reaction 1A

Startingmolecule

Product

ndash

Enzyme 2

Reaction 2B

Enzyme 3

Reaction 3C D

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 115: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Many beneficial drugs act as enzyme inhibitors including

bull ibuprofen which inhibits an enzyme involved in the production of prostaglandins (messenger molecules that increase the sensation of pain and inflammation)

bull some blood pressure medicinesbull some antidepressantsbull many antibiotics and bull protease inhibitors used to fight HIV

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 116: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 516

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 117: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

516 CONNECTION Many drugs pesticides and poisons are enzyme inhibitors

bull Enzyme inhibitors have also been developed as bull pesticides and bull deadly poisons for chemical warfare

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 118: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

You should now be able to

1 Describe the fluid mosaic structure of cell membranes

2 Describe the diverse functions of membrane proteins

3 Relate the structure of phospholipid molecules to the structure and properties of cell membranes

4 Define diffusion and describe the process of passive transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 119: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

You should now be able to

5 Explain how osmosis can be defined as the diffusion of water across a membrane

6 Distinguish between hypertonic hypotonic and isotonic solutions

7 Explain how transport proteins facilitate diffusion8 Distinguish between exocytosis endocytosis

phagocytosis and receptor-mediated endocytosis

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 120: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

You should now be able to

9 Define and compare kinetic energy potential energy chemical energy and heat

10 Define the two laws of thermodynamics and explain how they relate to biological systems

11 Define and compare endergonic and exergonic reactions

12 Explain how cells use cellular respiration and energy coupling to survive

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 121: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

You should now be able to

13 Explain how ATP functions as an energy shuttle14 Explain how enzymes speed up chemical

reactions15 Explain how competitive and noncompetitive

inhibitors alter an enzymersquos activity16 Explain how certain drugs pesticides and

poisons can affect enzymes

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 122: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 5UN01

Passive transport(requires no energy)

Active transport(requires energy)

Diffusion Facilitateddiffusion

Higher soluteconcentration

Lower soluteconcentration

Osmosis

Higher free waterconcentration

Solute

Water

Lower free waterconcentration

Higher soluteconcentration

ATP

Lower soluteconcentration

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 123: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 5UN02

Molecules crosscell membranes

by

passivetransport (a)

may be movingdown

movingagainst

requires

(b) ATP

diffusion (d)

uses

(e)

(c) polar moleculesand ions

of of

uses

by

P

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 124: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 5UN03

bc

a

d

f

e

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 125: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 5UN04

Oocytes inbuffer

Oocytes inlow HgCl2

Oocytes inhigh HgCl2

Oocytes in lowHgCl2 and ME

Wat

er p

erm

eabi

lity

(rat

e of

osm

otic

sw

ellin

g)

Data from G M Preston et al Appearance of water channels in Xenopusoocytes expressing red cell CHIP28 protein Science 256 3385ndash7 (1992)

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05
Page 126: Chapter 5 Cell Transport

copy 2015 Pearson Education Inc

Figure 5UN05

  • Slide 1
  • Introduction
  • Introduction (2)
  • Figure 50-1
  • Figure 50-2
  • Slide 6
  • 51 VISUALIZING THE CONCEPT Membranes are fluid mosaics of lip
  • Animation Overview of Cell Signaling
  • Animation Signal Transduction Pathways
  • Figure 51
  • Figure 51-1
  • Figure 51-2
  • Figure 51-3
  • Figure 51-4
  • Figure 51-5
  • Figure 51-6
  • Figure 51-7
  • Figure 51-8
  • Figure 51-9
  • 52 EVOLUTION CONNECTION The spontaneous formation of membrane
  • Figure 52
  • 53 Passive transport is diffusion across a membrane with no en
  • Figure 53a
  • Figure 53b
  • 53 Passive transport is diffusion across a membrane with no en (2)
  • Animation Diffusion
  • Animation Membrane Selectivity
  • 54 Osmosis is the diffusion of water across a membrane
  • Animation Osmosis
  • 54 Osmosis is the diffusion of water across a membrane (2)
  • Figure 54
  • 55 Water balance between cells and their surroundings is cruci
  • 55 Water balance between cells and their surroundings is cruci (2)
  • Figure 55
  • Figure 55 (2)
  • 55 Water balance between cells and their surroundings is cruci (3)
  • 55 Water balance between cells and their surroundings is cruci (4)
  • Video Chlamydomonas
  • Video Paramecium Vacuole
  • Video Plasmolysis
  • Video Turgid Elodea
  • Figure 55 (3)
  • 56 Transport proteins can facilitate diffusion across membrane
  • Figure 56
  • 56 Transport proteins can facilitate diffusion across membrane (2)
  • 56 Transport proteins can facilitate diffusion across membrane (3)
  • 57 SCIENTIFIC THINKING Research on another membrane protein l
  • Figure 57
  • 58 Cells expend energy in the active transport of a solute
  • Animation Active Transport
  • Figure 58-1
  • Figure 58-2
  • Figure 58-3
  • 59 Exocytosis and endocytosis transport large molecules across
  • 59 Exocytosis and endocytosis transport large molecules across (2)
  • Animation Exocytosis and Endocytosis Introduction
  • Animation Exocytosis
  • Animation Pinocytosis
  • Animation Phagocytosis
  • Animation Receptor-Mediated Endocytosis
  • Figure 59-0
  • Figure 59-1
  • Figure 59-2
  • Slide 64
  • 510 Cells transform energy as they perform work
  • 510 Cells transform energy as they perform work (2)
  • 510 Cells transform energy as they perform work (3)
  • 510 Cells transform energy as they perform work (4)
  • Animation Energy Concepts
  • 510 Cells transform energy as they perform work (5)
  • 510 Cells transform energy as they perform work (6)
  • 510 Cells transform energy as they perform work (7)
  • Figure 510-0
  • Figure 510-1
  • Figure 510-2
  • 511 Chemical reactions either release or store energy
  • 511 Chemical reactions either release or store energy (2)
  • Figure 511a
  • 511 Chemical reactions either release or store energy (3)
  • Figure 511b
  • 511 Chemical reactions either release or store energy (4)
  • 511 Chemical reactions either release or store energy (5)
  • 511 Chemical reactions either release or store energy (6)
  • 512 ATP drives cellular work by coupling exergonic and endergo
  • 512 ATP drives cellular work by coupling exergonic and endergo (2)
  • Figure 512a-1
  • Figure 512a-2
  • 512 ATP drives cellular work by coupling exergonic and endergo (3)
  • Figure 512b
  • 512 ATP drives cellular work by coupling exergonic and endergo (4)
  • Figure 512c
  • Slide 92
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (2)
  • 513 Enzymes speed up the cellrsquos chemical reactions by lowering (3)
  • Animation How Enzymes Work
  • Figure 513-0
  • Figure 513-1
  • Figure 513-2
  • Figure 513-3
  • Figure 513-4
  • 514 A specific enzyme catalyzes each cellular reaction
  • 514 A specific enzyme catalyzes each cellular reaction (2)
  • Figure 514-1
  • Figure 514-2
  • Figure 514-3
  • Figure 514-4
  • 514 A specific enzyme catalyzes each cellular reaction (3)
  • 514 A specific enzyme catalyzes each cellular reaction (4)
  • 515 Enzyme inhibition can regulate enzyme activity in a cell
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (2)
  • Figure 515a
  • 515 Enzyme inhibition can regulate enzyme activity in a cell (3)
  • Figure 515b
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme
  • Figure 516
  • 516 CONNECTION Many drugs pesticides and poisons are enzyme (2)
  • You should now be able to
  • You should now be able to (2)
  • You should now be able to (3)
  • You should now be able to (4)
  • Figure 5UN01
  • Figure 5UN02
  • Figure 5UN03
  • Figure 5UN04
  • Figure 5UN05

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