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
copy 2015 Pearson Education Inc
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
copy 2015 Pearson Education Inc
Introduction
bull This chapter addresses how working cells usebull membranesbull energy and bull enzymes
copy 2015 Pearson Education Inc
Figure 50-1
copy 2015 Pearson Education Inc
Figure 50-2 Chapter 5 Big Ideas
Membrane Structureand Function
Energy and the Cell
How Enzymes Function
Cellular respiration
ATPATP
copy 2015 Pearson Education Inc
MEMBRANE STRUCTURE AND FUNCTION
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
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
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
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
copy 2015 Pearson Education Inc
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
copy 2015 Pearson Education Inc
Introduction
bull This chapter addresses how working cells usebull membranesbull energy and bull enzymes
copy 2015 Pearson Education Inc
Figure 50-1
copy 2015 Pearson Education Inc
Figure 50-2 Chapter 5 Big Ideas
Membrane Structureand Function
Energy and the Cell
How Enzymes Function
Cellular respiration
ATPATP
copy 2015 Pearson Education Inc
MEMBRANE STRUCTURE AND FUNCTION
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
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
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
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
copy 2015 Pearson Education Inc
Introduction
bull This chapter addresses how working cells usebull membranesbull energy and bull enzymes
copy 2015 Pearson Education Inc
Figure 50-1
copy 2015 Pearson Education Inc
Figure 50-2 Chapter 5 Big Ideas
Membrane Structureand Function
Energy and the Cell
How Enzymes Function
Cellular respiration
ATPATP
copy 2015 Pearson Education Inc
MEMBRANE STRUCTURE AND FUNCTION
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
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
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
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
copy 2015 Pearson Education Inc
Figure 50-1
copy 2015 Pearson Education Inc
Figure 50-2 Chapter 5 Big Ideas
Membrane Structureand Function
Energy and the Cell
How Enzymes Function
Cellular respiration
ATPATP
copy 2015 Pearson Education Inc
MEMBRANE STRUCTURE AND FUNCTION
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
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
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
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
copy 2015 Pearson Education Inc
Figure 50-2 Chapter 5 Big Ideas
Membrane Structureand Function
Energy and the Cell
How Enzymes Function
Cellular respiration
ATPATP
copy 2015 Pearson Education Inc
MEMBRANE STRUCTURE AND FUNCTION
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
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
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
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
copy 2015 Pearson Education Inc
MEMBRANE STRUCTURE AND FUNCTION
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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)