Cell Structure & Cell Structure & FunctionFunction
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Microscope HistoryMicroscope HistoryHooke’s (1665) Hooke’s (1665)
drawings of drawings of corkcork
Early light Early light microscopemicroscope
Electron Electron microscopemicroscope
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Microscopic ImagesMicroscopic Images
ParameciumParamecium
LightLightMicrographMicrograph Scanning ElectronScanning Electron
Micrograph Micrograph
Transmission ElectronTransmission Electron Micrograph Micrograph
Scanning ElectronScanning Electron Micrograph Micrograph
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Cell TheoryCell Theory
All living things are composed of one or All living things are composed of one or more cellsmore cells
Cells are:Cells are:
• Basic unit of structureBasic unit of structure
• Basic unit of functionBasic unit of function
All cells come from preexisting cellsAll cells come from preexisting cells
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Basic Cell StructureBasic Cell Structure
All cells possess a plasma membrane, All cells possess a plasma membrane, cytoplasm, genetic materialcytoplasm, genetic material
Plasma membrane has phospholipid Plasma membrane has phospholipid bilayer, embedded glycoproteinsbilayer, embedded glycoproteins• Isolates cytoplasm from environmentIsolates cytoplasm from environment
• Regulates molecular movement into and out Regulates molecular movement into and out of cellof cell
• Interacts with other cells/environmentInteracts with other cells/environment
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AmoebaAmoeba
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Relative SizesRelative Sizes
100 m
10 m
1 m
10 cm
1 cm
1 mm
100 m
10 m
1 m
100 nm
10 nm
1 nm
0.1 nm
Elec
tron
Mic
rosc
ope
Ligh
t Mic
rosc
ope
Una
ided
eye
Spec
ial
E.M
.
Eukaryotic CellsEukaryotic Cells
VirusVirus
ProteinsProteins
AtomsAtoms
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Cell TypesCell Types
Prokaryotic:Prokaryotic:• Smaller, 1—5 µmSmaller, 1—5 µm• No organellesNo organelles• No nucleusNo nucleus• DNA in circular loop DNA in circular loop
Eukaryotic:Eukaryotic:• Larger, 8—100 µmLarger, 8—100 µm• Membranous organellesMembranous organelles• NucleusNucleus• DNA in linear chromosomesDNA in linear chromosomes
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Generalized ProkaryoteGeneralized Prokaryote
CapsuleCapsule
Cell WallCell WallPlasmaPlasmaMembraneMembrane
CytosolCytosol
Nucleoid DNANucleoid DNA
FlagellumFlagellum
Plasmid DNAPlasmid DNA
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Bacilli (1000x)Bacilli (1000x)
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Eukaryotic CellsEukaryotic Cells
Genetic material - DNA, found in the nucleusGenetic material - DNA, found in the nucleus
Cytoplasm – everything else within the plasma Cytoplasm – everything else within the plasma membranemembrane
• Cytosol (the fluid part)Cytosol (the fluid part)
– WaterWater
– SaltsSalts
– Organic monomers and polymersOrganic monomers and polymers
• OrganellesOrganelles
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Generalized Cell Generalized Cell AnimalAnimal
CellCellAnimalAnimal
CellCell
PlantPlantCellCell
PlantPlantCellCell
NucleusNucleus
GolgiGolgi
MitochondriaMitochondria
EndoplasmicEndoplasmicReticulumReticulum
CentriolesCentrioles ChloroplastsChloroplasts
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AnimalAnimalCellCell
AnimalAnimalCellCell
PlantPlantCellCell
PlantPlantCellCell
Generalized CellGeneralized Cell
NucleolusNucleolus
RibosomesRibosomes
Central VacuoleCentral Vacuole
Smooth E.R.Smooth E.R. Cell WallCell Wall
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1.1.Control StructuresControl Structuresa. Nucleusa. Nucleus
a. Nucleusa. Nucleus Structure:Structure:
• about 5 about 5 m in diameterm in diameter• bound within the nuclear envelopebound within the nuclear envelope• contains DNA complex (chromatin)contains DNA complex (chromatin)
Function:Function:• genes within DNA include instructions genes within DNA include instructions
for production of proteins to control for production of proteins to control metabolism and other cell functionsmetabolism and other cell functions
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The NucleusThe NucleusNucleolusNucleolus
PoresPores
Chromatin ThreadsChromatin Threads(Chromosomes)(Chromosomes) NuclearNuclear
EnvelopeEnvelope
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ChromosomesChromosomes
NucleoliNucleoli
NucleusNucleus
Cell WallCell Wall
ChromosomesChromosomes
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1.1.Control Structures Control Structures b. Nuclear Envelopeb. Nuclear Envelope
Structure:Structure:• double membrane (two bilipid layers)double membrane (two bilipid layers)• nuclear lamina (protein network)nuclear lamina (protein network)
– between membrane layers (20-40 nm)between membrane layers (20-40 nm)• perforated by pores (100 nm diameter)perforated by pores (100 nm diameter)
Function:Function:• stabilizes shape stabilizes shape • part of endomembrane systempart of endomembrane system
(transport)(transport)
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1.1.Control StructuresControl Structuresc. Nucleolusc. Nucleolus
Structure:Structure:• spherical region in nucleusspherical region in nucleus• composed of RNAcomposed of RNA
Function:Function:• packages ribosome subunitspackages ribosome subunits
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1.1.Control StructuresControl Structures d. Ribosomesd. Ribosomes
Structure:Structure:• complexes of RNA and proteinscomplexes of RNA and proteins• composed of two subunitscomposed of two subunits
Function: (as either free or bound)Function: (as either free or bound)• free ribososmes free ribososmes make proteinsmake proteins that that
function in the cytoplasmfunction in the cytoplasm• bound (to ER) ribosomes bound (to ER) ribosomes make proteinsmake proteins
destined for membranes or for exportdestined for membranes or for export
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RibosomesRibosomes
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2. Endomembrane System2. Endomembrane Systema. ER (Endoplasmic Reticulum)a. ER (Endoplasmic Reticulum)
Structure:Structure:• continuous with outer membrane of continuous with outer membrane of nuclear envelopenuclear envelope• folded membrane networkfolded membrane network
Function: (as either smooth or rough)Function: (as either smooth or rough)• rough ER (studded with ribosomes) makes rough ER (studded with ribosomes) makes
proteins and membranes (grow in place)proteins and membranes (grow in place)• smooth ER makes lipids, phospholipids, smooth ER makes lipids, phospholipids,
and steroidsand steroids
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Rough vs. Smooth ER: TEMRough vs. Smooth ER: TEM
Rough ERRough ERRough ERRough ER
Smooth ERSmooth ERSmooth ERSmooth ER
RibosomesRibosomes
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The Endoplasmic ReticulumThe Endoplasmic Reticulum
RibosomesRibosomes
UnitUnitMembraneMembrane
VesiclesVesiclesformingforming
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2. Endomembrane System2. Endomembrane System b. Golgi Apparatusb. Golgi Apparatus
Structure:Structure:• stack of flattened membrane sacsstack of flattened membrane sacs• two faces two faces
– ciscis “receiving” “receiving” – transtrans “shipping” “shipping”
Function:Function:• receives molecules from ER for processingreceives molecules from ER for processing• molecules are modified and packaged molecules are modified and packaged
as they are passed from sac to sacas they are passed from sac to sac
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The Golgi ComplexThe Golgi ComplexMaterial Material
ReceivedReceivedFrom ERFrom ER
Material DestinedMaterial Destinedfor Exportfor Export
TEMTEM
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2. Endomembrane System2. Endomembrane System c. Lysosomesc. Lysosomes
Structure:Structure:
• Small membrane sacs made by GolgiSmall membrane sacs made by Golgi
• Vesicles contain hydrolytic enzymesVesicles contain hydrolytic enzymes
Function:Function:
• Digest material engulfed by cellDigest material engulfed by cell
• Digest and recycle damaged organellesDigest and recycle damaged organelles
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2. Endomembrane System2. Endomembrane System d. Central Vacuolesd. Central Vacuoles
Structure:Structure:• Large, water-filled spaces (cell sap)Large, water-filled spaces (cell sap)
• Can take up over 90% of cell volumeCan take up over 90% of cell volume
• Enclosed by tonoplast (single membrane)Enclosed by tonoplast (single membrane)
Function:Function:• Storage of pigments (red/blue), acids, salts, Storage of pigments (red/blue), acids, salts,
wasteswastes
• Maintain cell pressure (turgor pressure)Maintain cell pressure (turgor pressure)
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Plant Wilting &Plant Wilting &the Central Vacuolethe Central Vacuole
VacuoleVacuole(tonoplast)(tonoplast) Cell WallCell Wall
Cyt
opla
sm
Cyt
opla
sm
NormalNormalPlant CellPlant Cell
In SaltIn SaltWaterWater
Space between Cell WallSpace between Cell Walland Cell Membraneand Cell Membrane
Normal
In Salt Water
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2. Endomembrane System2. Endomembrane System e. Contractile Vacuolee. Contractile Vacuole
Structure: Structure: • Membrane-bounded sac Membrane-bounded sac
• Connected to canals radiating through cytoplasm Connected to canals radiating through cytoplasm
Function:Function:• Control water balance in hypotonic environment.Control water balance in hypotonic environment.
• Fills with water entering cytoplasm (due to osmosis).Fills with water entering cytoplasm (due to osmosis).
• Pumps water out of the cell by contractingPumps water out of the cell by contracting
• Requires ATPRequires ATP
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Contractile VacuolesContractile Vacuoles
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2222
Paramecium sp.
Expelling WaterExpelling Waterto Outsideto Outside
ExpandedExpandedwith Waterwith Water
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The Endomembrane SystemThe Endomembrane System
LysosomeLysosome
Vessicle forVessicle forExportExport
GolgiGolgiEndoplasmicEndoplasmic
ReticulumReticulum
Vessicle Vessicle
Food Food VacuoleVacuole
Food Food VacuoleVacuole
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3. Other Membranous Organelles3. Other Membranous Organellesa. Plastidsa. Plastids
• a group of plant and algal membrane-a group of plant and algal membrane-bound organellesbound organelles
i.i. Chromoplasts (Chromoplasts (chromo = colorchromo = color))• pigment containing plastidspigment containing plastids
• fruits, flowers, autumn leavesfruits, flowers, autumn leaves
ii. ii. Amyloplasts (Amyloplasts (amylo = starchamylo = starch))• colorless plastids that store starch colorless plastids that store starch
• found in roots and tubersfound in roots and tubers
iii.iii. Chloroplasts (Chloroplasts (chloro = greenchloro = green))
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The AmyloplastThe Amyloplast
DoubleDoubleBilipidBilipid
MembraneMembrane
StarchStarchGranulesGranules
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a. Plastids a. Plastids iii. Chloroplastiii. Chloroplast
Structure:Structure:• Contain chlorophyllContain chlorophyll• Bounded by a double membraneBounded by a double membrane• Thylakoid staked into granaThylakoid staked into grana• Stroma (viscous fluid) outside thylakoidsStroma (viscous fluid) outside thylakoids• Contain ribosomes and some DNAContain ribosomes and some DNA
Function:Function:• Site of PhotosynthesisSite of Photosynthesis
– Captures light energyCaptures light energy– Produces carbohydrate from COProduces carbohydrate from CO22 and H and H22OO
• Self-replicating (semi-autonomous)Self-replicating (semi-autonomous)
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The ChloroplastThe Chloroplast
ThylakoidsThylakoids
OuterOuterMembraneMembrane
Intermembrane Intermembrane SpaceSpace
GranumGranum
StromaStroma
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Elodea (400x)Elodea (400x)
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3. Other Membranous Organelles3. Other Membranous Organelles b. Mitochondriab. Mitochondria
Structure: Structure: • Bounded by double membraneBounded by double membrane• Inner membrane folded into cristaeInner membrane folded into cristae• Mitochondrial matrix – within cristaeMitochondrial matrix – within cristae• Contain own DNA and ribosomes Contain own DNA and ribosomes
Function:Function:• Site of cellular respirationSite of cellular respiration
– convert energy stored in food into ATPconvert energy stored in food into ATP– ““powerhouse” of the cellpowerhouse” of the cell– number varies, but related to cell’s metabolic activitynumber varies, but related to cell’s metabolic activity
• Self-replicating (semi-autonomous)Self-replicating (semi-autonomous)
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The MitochondrionThe Mitochondrion
CristaeCristaeMatrixMatrix
OuterOuterMembraneMembrane
InnerInnerMembraneMembrane
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4. The Cytoskeleton4. The Cytoskeleton
Protein fibersProtein fibers• Cell shape; networks of intermediate Cell shape; networks of intermediate
filamentsfilaments• Cell movement; microfilaments & Cell movement; microfilaments &
microtubulesmicrotubules– Amoeboid movementAmoeboid movement– Muscle contractionMuscle contraction– Cell migration during developmentCell migration during development
• Organelle movement & suspensionOrganelle movement & suspension– Cyclosis; pathways for vesicle migrationCyclosis; pathways for vesicle migration
• Cell divisionCell division
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The CytoskeletonThe Cytoskeleton
MicrotubuleMicrotubule
MicrofilamentsMicrofilaments
IntermediateIntermediateFilamentsFilaments
Actin monomersActin monomers
Tubulin dimerTubulin dimer
EndoplasmicReticulum
Mitochondrion
PlasmaMembrane
Fibrous subunitsFibrous subunits
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4. The Cytoskeleton4. The Cytoskeleton a. Centriolesa. Centrioles
Structure:Structure:• Pair of cylindrical structuresPair of cylindrical structures
– 9 sets of triplet 9 sets of triplet microtubulesmicrotubules– Arranged in a ring Arranged in a ring
• ~ 50 nm at right angles~ 50 nm at right angles
Function:Function:• Replicate during cell divisionReplicate during cell division
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Centriole x.s.Centriole x.s.
T.E.M.
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4. The Cytoskeleton4. The Cytoskeleton b. Cilia and Flagellab. Cilia and Flagella
Structure:Structure:• Tubular extensions of plasma membraneTubular extensions of plasma membrane• Anchored by basal body (like centriole)Anchored by basal body (like centriole)• ““9+2” arrangement9+2” arrangement
– 9 doublet 9 doublet microtubulesmicrotubules in complex in complex– 2 single 2 single microtubulesmicrotubules in center in center
Function:Function:• Movement of fluid, or locomotionMovement of fluid, or locomotion
– Cilia: numerous, paddle-like, synchronizedCilia: numerous, paddle-like, synchronized– Flagella: longer, fewer, more whip-likeFlagella: longer, fewer, more whip-like
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Cilia & FlagellaCilia & Flagellax.s.x.s.
CellCellMembraneMembrane
ShaftShaft
BaseBase(a Centriole)(a Centriole)
T.E.M.
Paramecium
Euglena
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Flagellum PartsFlagellum PartsShaft, l.s.Shaft, l.s.
Shaft,Shaft,x.s.x.s. Microtubule Microtubule DoubletsDoublets
Cell MembraneCell Membrane
Dynein ArmsDynein Arms
Central Central SingletsSinglets
Microtubule Microtubule TripletsTriplets
Basal BodyBasal BodyBasal Body,Basal Body,
x.s.x.s.
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Flagella MovementFlagella Movement
Scanning E.M.Scanning E.M.of sperm on eggof sperm on eggScanning E.M.Scanning E.M.
of sperm on eggof sperm on egg
Corkscrew Movement(Pulls)
Whipping Movement(Pushes)
Water Water
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Movement of CiliaMovement of CiliaActive Stroke Recovery Stroke
Water
Cilia on Cilia on trachea trachea surfacesurface
Cilia on Cilia on trachea trachea surfacesurface
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5. Surfaces and Junctions5. Surfaces and Junctionsa. Cell Walla. Cell Wall
Structure:Structure:• Microfibrils of Cellulose in a MatrixMicrofibrils of Cellulose in a Matrix
– Primary Cell WallPrimary Cell WallThin, flexibleThin, flexible
– Secondary Cell WallSecondary Cell WallDeposited in Laminated LayersDeposited in Laminated Layers
• Middle LamellaMiddle Lamella– Sticky polysaccharides (pectins)Sticky polysaccharides (pectins)
Function:Function:• Protects and Maintains ShapeProtects and Maintains Shape• Holds Cells TogetherHolds Cells Together• Prevents Excess Water IntakePrevents Excess Water Intake
49 The Cell WallThe Cell WallThe Cell WallThe Cell Wall
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5. Surfaces and Junctions5. Surfaces and Junctionsb. Communication Structuresb. Communication Structures
DesmosomeDesmosome
desmosomedesmosomeProtein strandsrivet cells together,
but permit passage of substances
Protein strandsrivet cells together,
but permit passage of substances
Protein filamentsin cytoplasmProtein filamentsin cytoplasm
Small intestineSmall intestine Plasma membrane(edge view)Plasma membrane(edge view)
Cells liningsmall intestineCells liningsmall intestine
Tight JunctionTight Junction
Tight junctionsformed by strandsof protein
Tight junctionsformed by strandsof protein
Plasma membrane(edge view)Plasma membrane(edge view)
Cells liningbladderCells liningbladder
Tight junctionsseal membranesto block transport
Tight junctionsseal membranesto block transport
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5. Surfaces and Junctions5. Surfaces and Junctionsc. Attachment Structuresc. Attachment Structures
Gap JunctionsGap Junctions
desmosomedesmosomeGap Junctions:pairs of channelsconnect insides ofadjacent cells
Gap Junctions:pairs of channelsconnect insides ofadjacent cells
LiverLiverPlasma membranePlasma membrane
Liver cellsLiver cells
PlasmodesmataPlasmodesmata
Plasmodesmataallows passageinto adjacent cells
Plasma membrane(lines cell and channels)
Root cells
Cell wall(cellulose)
Middle lamella(pectin)
RootRoot
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