The CellThe Cell

Microscopes, History & the Microscopes, History & the Cell TheoryCell Theory

The MicroscopeThe Microscope

►Originally created for trade purposesOriginally created for trade purposes►Merchants needed a way of examining Merchants needed a way of examining

types of fibers more closely (i.e., silk, types of fibers more closely (i.e., silk, wool, etc) to ensure quality of the wool, etc) to ensure quality of the productproduct

Anton van LeeunwenhoekAnton van Leeunwenhoek

►Dutch biologistDutch biologist►Generally credited Generally credited

w/developing first microscope w/developing first microscope (early to mid 1600’s)(early to mid 1600’s)

► Studied never-before-seen Studied never-before-seen living organisms in pond water, living organisms in pond water, blood cells and bacteriablood cells and bacteria

► Called what he saw Called what he saw ““animalculesanimalcules” and “” and “beastiesbeasties””

Robert HookeRobert Hooke

►English scientistEnglish scientist►Examined cork slices and other Examined cork slices and other

plantplant tissuestissues under a microscope under a microscope►What he saw were the remnants of What he saw were the remnants of

dead cellsdead cells

►He saw box-like structures he He saw box-like structures he called ‘called ‘cells’cells’

►Named them after the rooms in a Named them after the rooms in a monastery lived in monastery lived in

The Happenin’ 1800’sThe Happenin’ 1800’s

►1824-French scientist Henry Dutrochet 1824-French scientist Henry Dutrochet says all living things are made of cellssays all living things are made of cells

►1831-Scottish scientist Robert Brown 1831-Scottish scientist Robert Brown calls the dense round body in the calls the dense round body in the middle of a cell the “middle of a cell the “nucleusnucleus””

►Didn’t know the function of the nucleusDidn’t know the function of the nucleus

The Happenin’ 1800’s:The Happenin’ 1800’s:The Big ThreeThe Big Three

►1838-German botanist 1838-German botanist Matthias SchleidenMatthias Schleiden says all plants are made of cellssays all plants are made of cells

►1839-Zoologist 1839-Zoologist Theodor SchwannTheodor Schwann says all says all animals are made of cellsanimals are made of cells

►1855-German Physician 1855-German Physician Rudolf VirchowRudolf Virchow says that all cells arise from pre-existing says that all cells arise from pre-existing cellscells

►These guys helped to form the “Cell These guys helped to form the “Cell Theory”Theory”

The Cell TheoryThe Cell Theory: The modern : The modern VersionVersion

► 1. All organisms are made up of cells.1. All organisms are made up of cells.► 2. New cells are always produced from pre-2. New cells are always produced from pre-

existing cells.existing cells.► 3. The cell is a structural and functional unit of all 3. The cell is a structural and functional unit of all

living things.living things.► 4. The cell contains hereditary information 4. The cell contains hereditary information

which is passed on from cell to cell during which is passed on from cell to cell during cell division. cell division.

► 5. All cells are basically the same in chemical 5. All cells are basically the same in chemical composition and metabolic activitiescomposition and metabolic activities

The Cell StructureThe Cell Structure

Types of Cells, Examples and Types of Cells, Examples and OrganellesOrganelles

Cell Size Limitations: Think “The Cell Size Limitations: Think “The Roman Empire”Roman Empire”

►Cell size is limited by the: Cell size is limited by the: ►The flow of The flow of informationinformation and and materialsmaterials through the cell through the cell

► The cell on the right takes 5 The cell on the right takes 5 times as long to get info from times as long to get info from nucleus to membrane!nucleus to membrane!

Two Types of CellsTwo Types of Cells

► Two major categories of cells based upon Two major categories of cells based upon nucleinuclei Eukaryotic CellsEukaryotic Cells ((EukaryotesEukaryotes))

►Have a nucleus and membrane-bound Have a nucleus and membrane-bound organellesorganelles

Prokaryotic CellsProkaryotic Cells ((Prokaryotes)Prokaryotes)►Do NOT have a nucleusDo NOT have a nucleus►No internal membrane-bound organellesNo internal membrane-bound organelles

Eukaryotic and Prokaryotic Eukaryotic and Prokaryotic CellsCells

Eukaryotic Organisms Comprise Eukaryotic Organisms Comprise 4 of the 5 Kingdoms4 of the 5 Kingdoms

►Single-Celled EukaryotesSingle-Celled Eukaryotes Kingdom Kingdom ProtistaProtista: : ProtistsProtists including including AlgaeAlgae Kingdom Kingdom FungiFungi: : YeastsYeasts

►Multi-celled EukaryotesMulti-celled Eukaryotes Kingdom Kingdom FungiFungi: : Molds, MushroomsMolds, Mushrooms Kingdom Kingdom PlantePlante: : PlantsPlants Kingdom Kingdom AnimaliaAnimalia: : AnimalsAnimals

Prokaryotic Organisms Comprise Prokaryotic Organisms Comprise the Kingdom Monerathe Kingdom Monera

►Monera include all of the Monera include all of the bacteriabacteria

►The simple structure of bacteria, and The simple structure of bacteria, and prokaryotic cells in general, make prokaryotic cells in general, make them the them the most numerousmost numerous of all the of all the kingdomskingdoms

Basic Cell StructureBasic Cell Structure

►Three common Three common organellesorganelles (little (little organs) to all Plant and Animal cells: organs) to all Plant and Animal cells:

►Cell MembraneCell Membrane ►NucleusNucleus ►CytoplasmCytoplasm

Cell MembraneCell Membrane

►Present in all cells Present in all cells ►The outer boundary of the cellThe outer boundary of the cell►Regulates what enters and exits the Regulates what enters and exits the

cellcell►Provides protection and supportProvides protection and support►REAL WORLD EXAMPLEREAL WORLD EXAMPLE: A chain link : A chain link

fence around a cityfence around a city

Cell Membrane StructureCell Membrane Structure

►Lipid BilayerLipid Bilayer (Composed of (Composed of Phospholipids-a type of fat)Phospholipids-a type of fat)

►ProteinsProteins imbedded in the bilayer imbedded in the bilayer provide:provide:

►SupportSupport►Channels for molecular transitChannels for molecular transit►Pumping action for transitPumping action for transit

►CarbohydratesCarbohydrates on cell surface act as on cell surface act as chemical identification for the bodychemical identification for the body

Diagram of Cell MembraneDiagram of Cell Membrane

Cell Membrane JunctionsCell Membrane Junctions

►Gap JunctionsGap Junctions CommunicationCommunication

►Tight JunctionsTight Junctions ImpermeableImpermeable

►DesmosomesDesmosomes AnchoringAnchoring

NucleusNucleus

►The control center of the cellThe control center of the cell►Not all cells have nuclei “true” nuclei Not all cells have nuclei “true” nuclei

(think of prokaryotes-i.e., bacteria!)(think of prokaryotes-i.e., bacteria!)►The most important part of the The most important part of the

nucleus is the DNA inside of it nucleus is the DNA inside of it The The genetic blueprint of lifegenetic blueprint of life

Nucleus StructureNucleus Structure

►The Nuclear EnvelopeThe Nuclear Envelope (also nuclear (also nuclear membrane)membrane)

►Two membranes closely held Two membranes closely held togethertogether

►Nuclear pores allow transit in and out Nuclear pores allow transit in and out of the envelopeof the envelope

►Real world example: Security Real world example: Security checkpoints at City Hallcheckpoints at City Hall

Nucleus StructureNucleus Structure

►NucleolusNucleolus Consists of the Consists of the Ribonucleic Acid (RNA)Ribonucleic Acid (RNA) and and

proteinprotein RibosomesRibosomes are made here are made here

►ChromosomesChromosomes Elaborate protein “frame” that holds and Elaborate protein “frame” that holds and

protects DNAprotects DNA

Nucleus DiagramNucleus Diagram

CytoplasmCytoplasm

►Gel/water-like material between the Gel/water-like material between the nucleus and the cell membranenucleus and the cell membrane

►Holds all the organelles in placeHolds all the organelles in place►Provides a place for chemical reactions Provides a place for chemical reactions

to take placeto take place

Cell WallCell Wall

►Found in Found in plants, algaeplants, algae and some and some bacteriabacteria►Lies outside the cell membraneLies outside the cell membrane►Provides protection and incredible supportProvides protection and incredible support►Very porous (lots of holes!) for important Very porous (lots of holes!) for important

molecules to pass throughmolecules to pass through►Made of multiple layers of different types Made of multiple layers of different types

of carbohydrates including of carbohydrates including CelluloseCellulose--otherwise known as fiberotherwise known as fiber

Cell Wall StructureCell Wall Structure

MitochondriaMitochondria

► Power station (animal cell)Power station (animal cell)► Takes chemical energy stored in food and Takes chemical energy stored in food and

converts it to a form the body can use-converts it to a form the body can use-ATPATP► Contains two membranes:Contains two membranes:

►Outer membrane surrounds and Outer membrane surrounds and protectsprotects

►Inner membrane folds to increase Inner membrane folds to increase surface areasurface area energy conversion happens hereenergy conversion happens here

ChloroplastsChloroplasts

►Power station (plant and algae cell)Power station (plant and algae cell)►Captures light energy from the sun Captures light energy from the sun

(using chlorophyll) and converts it into (using chlorophyll) and converts it into chemical energychemical energy

►The innermost membrane The innermost membrane captures the light energy from the captures the light energy from the sunsun

Chloroplast StructureChloroplast Structure

PlastidsPlastids

►Plant organelles w/many formsPlant organelles w/many forms►Chloroplasts are one formChloroplasts are one form

►Stores food and pigmentsStores food and pigments►Leukoplasts Leukoplasts Store food Store food►Chromoplasts Chromoplasts Store pigments Store pigments (coloration)(coloration)

RibosomesRibosomes

►Makes proteins from amino acidsMakes proteins from amino acids►Cells that need more protein will have Cells that need more protein will have

significantly more ribosomes (e.g., significantly more ribosomes (e.g., muscle cells will have more than skin muscle cells will have more than skin cells)cells)

►Composed of RNA and proteinsComposed of RNA and proteins►Membrane-bound or free-floatingMembrane-bound or free-floating►Among the smallest of the Among the smallest of the

organellesorganelles

Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER)

►Complex network of channels Complex network of channels throughout a cellthroughout a cell

►Acts as an superhighway within the Acts as an superhighway within the cell for transport of materialscell for transport of materials

►Two types of Endoplasmic ReticulumTwo types of Endoplasmic Reticulum►SmoothSmooth►RoughRough

Smooth Endoplasmic Smooth Endoplasmic ReticulumReticulum

►Have a smooth appearance (do not Have a smooth appearance (do not have ribosomes attached to them)have ribosomes attached to them)

►Some cells’ ER hold special enzymes Some cells’ ER hold special enzymes and chemicals for various functionsand chemicals for various functions

Rough Endoplasmic Rough Endoplasmic ReticulumReticulum

►Rough due to ribosomes being stuck to Rough due to ribosomes being stuck to the outsidethe outside

► Involved in making proteinsInvolved in making proteins►New proteins are inserted into Rough New proteins are inserted into Rough

ER for transport through the cellER for transport through the cell

Golgi ApparatusGolgi Apparatus

►Discovered by Italian scientist Camillo GolgiDiscovered by Italian scientist Camillo Golgi► Resembles a flattened stack of membranes Resembles a flattened stack of membranes

on top of one anotheron top of one another►Located by the cell membraneLocated by the cell membrane

► Assists in the Assists in the collectioncollection, , modificationmodification, , packagingpackaging and and distributiondistribution of proteins and of proteins and other molecules throughout the cellother molecules throughout the cell

► The The UPS-United Parcel ServiceUPS-United Parcel Service of the cell of the cell

LysosomesLysosomes

► The “Cleanup Crew” of the cellThe “Cleanup Crew” of the cell► Small, they contain chemicals and enzymes Small, they contain chemicals and enzymes

for digestionfor digestion► Involved in cleaning up cell parts, Involved in cleaning up cell parts,

molecules, etc. that have died or outlived molecules, etc. that have died or outlived their usefulness their usefulness

► Formed by the Formed by the Golgi ApparatusGolgi Apparatus►Also called the “Suicide Sac”Also called the “Suicide Sac”

LysosomesLysosomes

► Conducts the process of Conducts the process of endocytosisendocytosis► Engulfing of large particles too big to fit Engulfing of large particles too big to fit

through a cell membranethrough a cell membrane

VacuolesVacuoles

►Saclike structure that:Saclike structure that: Stores water, salts, proteins and Stores water, salts, proteins and

carbohydratescarbohydrates►Found in plant and animal cellsFound in plant and animal cells►Vacuole is much larger in plants Vacuole is much larger in plants

due to enormous amounts of due to enormous amounts of water being storedwater being stored

►Builds up water pressure and Builds up water pressure and makes plants sturdymakes plants sturdy

CytoskeletonCytoskeleton

►Cell frameworkCell framework►Composed of filaments and fibers that Composed of filaments and fibers that

help maintain shape, aide in transport, help maintain shape, aide in transport, etc.etc.

►Composed of two parts:Composed of two parts:►MicrotublesMicrotubles►MictrofilamentsMictrofilaments

MicrotublesMicrotubles

►Hollow tubes made from proteinHollow tubes made from protein► ProvideProvide ssupportupport & & organelle transportorganelle transport► Aide in cell division by forming Aide in cell division by forming centriolescentrioles

(animal cells only)(animal cells only)► Support Support Cilia and FlagellaCilia and Flagella

►Finger-like or whip-like structures that Finger-like or whip-like structures that help with: help with:

►Cell movementCell movement►Movement along the cell surfaceMovement along the cell surface

MicrofilamentsMicrofilaments

►Long, thin fibers made of proteinsLong, thin fibers made of proteins►Provide:Provide:

►Support and movement of cellSupport and movement of cell►Movement of the cytoplasm (called Movement of the cytoplasm (called

cytoplasmic streaming)cytoplasmic streaming)

Cytoskeleton DiagramCytoskeleton Diagram

Maintaining a Maintaining a Constant Cell Constant Cell EnvironmentEnvironment

Osmosis & DiffusionOsmosis & Diffusion

DiffusionDiffusion

The process by The process by which molecules of a which molecules of a substance move substance move from areas of higher from areas of higher concentration of that concentration of that substance to areas substance to areas of lower of lower concentrationconcentration

DiffusionDiffusion

► In the fluid and gaseous state of matter:In the fluid and gaseous state of matter: Molecules are constantly in motion; colliding Molecules are constantly in motion; colliding

with one another and spreading out randomly with one another and spreading out randomly This random motion has a general patternThis random motion has a general pattern Molecules move from an area where there Molecules move from an area where there

are more molecules to where there are less are more molecules to where there are less moleculesmolecules

In other words, they move from an area of In other words, they move from an area of higher concentration to an area of lesser higher concentration to an area of lesser concentration.concentration.

EquilibriumEquilibrium

►The point at which the distribution of The point at which the distribution of molecules and materials are evenly molecules and materials are evenly spaced out in any given area.spaced out in any given area.

OsmosisOsmosis► The diffusion of water across a The diffusion of water across a

selectively permeableselectively permeable membrane.membrane.

► Some membranes are Some membranes are selectively permeable so some selectively permeable so some substances cannot pass substances cannot pass through or across them (Those through or across them (Those substances that “don’t mix substances that “don’t mix well” with the fat in the well” with the fat in the membrane).membrane).

► Water is the exception:Water is the exception:

Water doesn’t mix with Water doesn’t mix with lipids lipids howeverhowever its its molecules pass very rapidly molecules pass very rapidly through the membrane.through the membrane.

Osmotic PressureOsmotic Pressure

► The force exerted by osmosis.The force exerted by osmosis.► Tends to move water across a membrane Tends to move water across a membrane

from a dilute solution to a more from a dilute solution to a more concentrated solution.concentrated solution.

►When solutions are of equal concentration When solutions are of equal concentration (the desired state) then you have (the desired state) then you have equilibrium and equilibrium and NONO movement of water movement of water across the membrane.across the membrane.

Solution TypesSolution Types

Relative to a cell, there are Relative to a cell, there are three solution typesthree solution types

HypertonicHypertonic

►When the solution outside of a cell is When the solution outside of a cell is of higher concentration than the of higher concentration than the solution inside of a cell.solution inside of a cell.

►Water will leave the cell in order to Water will leave the cell in order to dilute the solution outside of the cell.dilute the solution outside of the cell.

HypotonicHypotonic

►When the solution outside of a cell is When the solution outside of a cell is of lesser concentration than the of lesser concentration than the solution inside of a cell.solution inside of a cell.

►Water will enter the cell in order to Water will enter the cell in order to dilute the solution inside of the cell. dilute the solution inside of the cell.

IsotonicIsotonic

►When the solution outside of a cell is When the solution outside of a cell is of the same concentration of the of the same concentration of the solution inside of a cell.solution inside of a cell.

►Water will neither enter nor leave the Water will neither enter nor leave the cell.cell.

►There will be no net movement of There will be no net movement of water.water.

Solution PicturesSolution Pictures

TransportTransport

Active v. Passive TransportActive v. Passive Transport

Passive TransportPassive Transport

►Transport of water from areas of Transport of water from areas of higher concentration to areas of lower higher concentration to areas of lower concentration (either across a concentration (either across a membrane or not) that requires membrane or not) that requires NONO energy.energy.

Facilitated DiffusionFacilitated Diffusion► Deals with the movement of molecules across a Deals with the movement of molecules across a

membrane that cannot cross a membrane by membrane that cannot cross a membrane by themselves.themselves.

► The channel proteins that facilitate the passage of The channel proteins that facilitate the passage of these molecules are typically specific to that particular these molecules are typically specific to that particular substance.substance. In other words, the proteins have an affinity for whatever In other words, the proteins have an affinity for whatever

substance is dissolved in the solution and will attract it.substance is dissolved in the solution and will attract it.

► Movement of the substance is reliant upon difference in Movement of the substance is reliant upon difference in charge of the molecules and the proteins.charge of the molecules and the proteins.

► This process DOES NOT require energy and so is This process DOES NOT require energy and so is diffusion driven.diffusion driven.

► Therefore, there must be a difference in concentration Therefore, there must be a difference in concentration on either side of the cell membrane.on either side of the cell membrane.

Active TransportActive Transport

►Energy requiring process that moves Energy requiring process that moves molecules across a membrane and molecules across a membrane and AGAINST a concentration gradient AGAINST a concentration gradient (from an area of lower concentration (from an area of lower concentration to an area of higher concentration).to an area of higher concentration).

Types of Active TransportTypes of Active Transport

►Pumping action:Pumping action: ““Pumps” move individual molecules across the membrane Pumps” move individual molecules across the membrane

and against the concentration gradient.and against the concentration gradient. Chemical energy is required to power the pumping action Chemical energy is required to power the pumping action

of the protein channel.of the protein channel. Calcium, potassium and sodium are among those Calcium, potassium and sodium are among those

substances transported across the membrane.substances transported across the membrane.► Called a “Sodium Potassium Pump”Called a “Sodium Potassium Pump”

Types of Active TransportTypes of Active Transport► EndocytosisEndocytosis

Particles “push” against the outside of the cell membrane Particles “push” against the outside of the cell membrane causing a pocket to form.causing a pocket to form.

This pocket breaks loose on the inside of the cell forming an This pocket breaks loose on the inside of the cell forming an individual vacuole, or storage structure.individual vacuole, or storage structure.

Large molecules, clumps of food and other cells can be Large molecules, clumps of food and other cells can be taken into the cytoplasm this way.taken into the cytoplasm this way.► PhagocytosisPhagocytosis::

A form or Endocytosis where large, solid particles are taken in.A form or Endocytosis where large, solid particles are taken in. Amebas feed this way.Amebas feed this way.

► PinocytosisPinocytosis:: When liquid forms pockets along the cell membrane, forms a When liquid forms pockets along the cell membrane, forms a

vacuole and is taken into the cell cytoplasm.vacuole and is taken into the cell cytoplasm.

► ExocytosisExocytosis When large particles push against the cell membrane from When large particles push against the cell membrane from

the inside and the membrane surrounds it as it leaves the the inside and the membrane surrounds it as it leaves the cell.cell.