Download - Ch. 7 Inside the Cell
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InsidetheCellBIOL222
Ch.7
Overview:TheFundamentalUnitsofLife
• Allorganismsaremadeofcells
• Thecellisthesimplestcollec=onofma>er
thatcanlive
• Cellstructureiscorrelatedtocellularfunc=on
• Allcellsarerelatedbytheirdescentfromearliercells
Fig.6-2
10 m
1 m
0.1 m
1 cm
1 mm
100 µm
10 µm
1 µm
100 nm
10 nm
1 nm
0.1 nm Atoms
Small molecules
Lipids
Proteins
Ribosomes
Viruses Smallest bacteria
Mitochondrion
Nucleus Most bacteria
Most plant and animal cells
Frog egg
Chicken egg
Length of some nerve and muscle cells
Human height
Una
ided
eye
Ligh
t mic
rosc
ope
Elec
tron
mic
rosc
ope
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• Prokaryo=ccells
• BacteriaandArchaebacteria
• Eukaryo=ccells
• Pro=sts,fungi,plants,andanimals
Prokaryo=candEukaryo=cCells
Prokaryo=candEukaryo=cCells
• Basicfeaturesofallcells:
• Plasmamembrane
• Semifluidsubstancecalledcytosol
• Cytoplasm=spaceinsidecell
• filledwithcytosol
• Chromosome(s)
• Gene=cinfo
• Ribosomes
• Proteinsynthesis
• Prokaryo=ccellscharacterizedby:
• Nonucleus
• nucleoidregioninstead
• DNAinanunboundarea
• Nomembranousorganelles
• Ribosomesonly
• Notmembranebound
• Cytoplasm
• enclosedbytheplasmamembrane
Prokaryo=cCells
Fimbriae
Nucleoid
Ribosomes
Plasma membrane
Cell wall
Capsule
Flagella
Bacterial chromosome
(a) A typical rod-shaped bacterium
(b)A thin section through the bacterium Bacillus coagulans (TEM)
0.5 µm
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• Eukaryo=ccellscharacterizedby
having:
• nucleus
• enclosesDNA
• boundedbyadouble
membranousenvelope
• Manymembranousorganelles
• Eukaryota
• muchlargerthanprokaryo=c
cells
• 10x-100xonaverage
Eukaryo=cCells
• plasmamembrane
• Selec=velypermeable
• allowssufficientpassageofoxygen,nutrients,andwaste
toservicethevolumeofeverycell
• Phospholipidbilayer
• amphipathic
• fluidmosaic
CellMembrane
• Limitstothesizeofcells
• Diffusioncanonlyworksofar
• efficiencydeclineswith
distance
• Surfaceareatovolumera=oofacellis
cri=cal
• Asthesurfaceareaincreasesbya
factorofn2,thevolumeincreases
byafactorofn3
• Smallcellshaveagreatersurface
arearela=vetovolume
CellMembrane
Surface area increases while total volume remains constant
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6 150 750
125 1251
6 61.2
Total surface area [Sum of the surface areas (height × width) of all boxes sides × number of boxes]
Total volume [height × width × length × number of boxes]
Surface-to-volume (S-to-V) ratio [surface area ÷ volume]
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APanoramicViewoftheEukaryo=cCell• Internalmembranes
• Par==onthecellinto
organelles
• Samematerialand
construc=on
• ascellmembrane
• Plantandanimalcells
• havemostofthesame
organelles
ENDOPLASMIC RETICULUM (ER)
Smooth ERRough ERFlagellum
Centrosome
CYTOSKELETON:Microfilaments
Intermediate filaments
Microtubules
Microvilli
Peroxisome
MitochondrionLysosome
Golgi apparatus
Ribosomes
Plasma membrane
Nuclear envelope
Nucleolus
Chromatin
NUCLEUS
NUCLEUSNuclear envelopeNucleolusChromatin
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Ribosomes
Central vacuole
MicrofilamentsIntermediate filamentsMicrotubules
CYTO- SKELETON
Chloroplast
PlasmodesmataWall of adjacent cell
Cell wall
Plasma membrane
PeroxisomeMitochondrion
Golgi apparatus
Nucleus• Nucleus
• containsmostofthecell’sgenesandisusuallythemostconspicuous(largest)organelle
• Mitochondriaand/orchloroplastsalsohavetheirownDNA
• mtDNA,ptDNA
• Nuclearenvelope
• enclosesthenucleus,separa=ngitfromthecytoplasm
• doublemembrane;eachmembraneconsistsofaphospholipidbilayer
• Studdedwithnuclearpores
ENDOPLASMIC RETICULUM (ER)
Smooth ERRough ERFlagellum
Centrosome
CYTOSKELETON:
Microfilaments
Intermediate filaments
Microtubules
Microvilli
Peroxisome
MitochondrionLysosome
Golgi apparatus
Ribosomes
Plasma membrane
Nuclear envelope
Nucleolus
Chromatin
NUCLEUS
Fig.6-10
NucleolusNucleus
Rough ER
Nuclear lamina (TEM)
Close-up of nuclear envelope
1 µm
1 µm
0.25 µm
Ribosome
Pore complex
Nuclear pore
Outer membraneInner membraneNuclear envelope:
Chromatin
Surface of nuclear envelope
Pore complexes (TEM)
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• NuclearPores
• regulatetheentry
andexitofmolecules
fromthenucleus
• Nuclearlamina
• maintainsshapeofthe
nucleus
• composedofprotein
• Intermediatefilaments
• Similartocytoskeleton
Nucleus
NucleolusNucleus
Rough ER
Nuclear lamina (TEM)
Close-up of nuclear envelope
1 µm
1 µm
0.25 µm
Ribosome
Pore complex
Nuclear pore
Outer membraneInner membraneNuclear envelope:
Chromatin
Surface of nuclear envelope
Pore complexes (TEM)
• Chroma=n
• DiffuseformofGene=cmaterialmadeofDNAandproteins
• Chromosomes
• Condensedchroma=n
• Onlyduringcelldivision
• Nucleolus
• siteofribosomalRNA(rRNA)synthesis
• locatedwithinthenucleus
• Seenaslargedarkspot
Nucleus
Ribosomes
• Ribosomes
• par=clesmadeof
ribosomalRNAandprotein
• Onlyorganellewithoutamembraneenclosure
• carryoutproteinsynthesisintwoloca=ons:
• Inthecytosol(freeribosomes)
• Ontheoutsideoftheendoplasmic
re=culumorthenuclearenvelope
(boundribosomes)
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Fig.6-11
Cytosol
Endoplasmic reticulum (ER)
Free ribosomes
Bound ribosomes
Large subunit
Small subunit
Diagram of a ribosomeTEM showing ER and ribosomes
0.5 µm
EndomembraneSystem• Componentsoftheendomembrane
system:
• Nuclearenvelope
• Endoplasmicre=culum
• Golgiapparatus
• Lysosomes
• Vacuoles
• Plasmamembrane
• Thesecomponentsareeither
con=nuousorconnectedviatransfer
byvesicles
Biosynthesis:EndoplasmicRe=culum
• Endoplasmicre=culum(ER)
• accountsformorethanhalfofthetotalmembraneinmany
eukaryo=ccells
• con=nuouswiththenuclearenvelope
• TworegionsofER:
• SmoothER
• Noribosomes
• RoughER
• Ribosomesa>ached
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Fig.6-12
Smooth ER
Rough ER Nuclear envelope
Transitional ER
Rough ERSmooth ERTransport vesicle
RibosomesCisternaeER lumen
200 nm
SmoothEndoplasmicRe=culum• ThesmoothER
• Synthesizeslipids
• Phospholipids
• Steroids
• Metabolizescarbs
• Glycogenolysis/
gluconeogenesis
• Detoxifiespoisons
• Storescalcium
• Sarcoplasmicre=culum
RoughEndoplasmicRe=culum
• RoughER
• Ribosomesa>ached
• Sitesofmembraneand
secretoryproteinsynthesis
• Transportvesicles
• Proteinssurroundedbymembranes
• BudfromRERmembrane
• Isamembranemanufacturingandassemblyfactoryforthecell
• AlongwithSER
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TheGolgiApparatus
cis face (“receiving” side of Golgi apparatus) Cisternae
trans face (“shipping” side of Golgi apparatus)
TEM of Golgi apparatus
0.1 µm
• Golgiapparatus
• Cisternae
• fla>enedmembranoussacs
• Func=ons:
• ModifiesproductsoftheER
• Manufacturessome
polysaccharides(pec=n)
• Sortsandpackages
materialsintotransport
vesicles
Lysosomes
• Lysosome
• membranoussacofhydroly=cenzymes
• digestmacromolecules
• hydrolyzeproteins,fats,polysaccharides,andnucleicacids
• Phagocytosis
• Onecellengulfinganother
• formsafoodvacuole
• fuseswithlysosome
• Autophagy
• Lysosomesuseenzymes
• torecyclethecell’sownorganelles
andmacromolecules
Lysosomes
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Fig.6-14
Nucleus 1 µm
LysosomeDigestive enzymes
Lysosome
Plasma membrane
Food vacuole
(a) Phagocytosis
Digestion
(b) Autophagy
Peroxisome
Vesicle
Lysosome
Mitochondrion
Peroxisome fragment
Mitochondrion fragment
Vesicle containing two damaged organelles 1 µm
Digestion
• Aplantcellorfungalcellmayhaveoneor
severalvacuoles
• Foodvacuoles
• formedbyphagocytosis
• Contrac=levacuoles
• foundinmanyfreshwaterpro=sts,
pumpexcesswateroutofcells
• Centralvacuoles
• foundinmanymatureplantcells,
holdorganiccompoundsandwater
Vacuoles
Central vacuole
Cytosol
Central vacuole
Nucleus
Cell wall
Chloroplast
5 µm
MitochondriaandChloroplasts
• Mitochondria
– sitesofcellularrespira=on
– Inplantstoo
• Chloroplasts
• inplantsandalgaeonly
• sitesofphotosynthesis
• Bothchangeenergyfromoneform
toanother
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• Mitochondriaandchloroplasts
• Arenotpartoftheendomembranesystem
• Haveadoublemembrane
• Haveproteinsmadebyfreeribosomes
• ContaintheirownDNA?!
• Endosymbionttheory
MitochondriaandChloroplasts
• hMp://www.sciencedaily.com/releases/2011/07/110725190046.htm
• hMp://www.nature.com/srep/2011/110614/srep00013/full/srep00013.html
Mitochondria• Mitochondria
• innearlyalleukaryo=ccells
• Allhaveevolu=onarydescendants
ofmitochondria
• Cristae
• Foldsofinnermembranetoincreasesurfacearea
• innermembrane
• createstwocompartments:
• intermembranespace
• ForH+gradientofelectrontransportchain
• mitochondrialmatrix
• ForKrebsCycle
Fig.6-17
Free ribosomes in the mitochondrial matrix
Intermembrane spaceOuter membrane
Inner membraneCristae
Matrix
0.1 µm
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• Chloroplaststructureincludes:
• Thylakoids
• membranoussacs,stackedtoformagranum
• Stroma
• internalfluid
Chloroplasts
Ribosomes
Thylakoid
Stroma
Granum
Inner and outer membranes
1 µm
Peroxisomes:Oxida=on• Peroxisomes
• Specializedmetaboliccompartments
• Boundbyasinglemembrane
• Oxygenusedtobreakdowndifferenttypesofmolecules
• H2O2by-productconvertedtowater
Cytoskeleton• Cytoskeleton
• networkofproteinfibersextending
throughoutthecytoplasm
• organizesthecell’sstructuresand
ac=vi=es
• anchorsmanyorganelles
• composedofthreetypesofmolecular
structures:
• Microtubules
• Microfilaments
• Intermediatefilaments
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Cytoskeleton:Support,Mo=lity,andRegula=on• Cytoskeleton
• supportthecellandmaintainitsshape
• motorproteins
• producemo=lity
• vesiclescantravelalong“monorails”
• providedbythecytoskeleton
• Recentevidencesuggests
• cytoskeletonmayhelpregulatebiochemical
ac=vi=es
PLAY
ComponentsoftheCytoskeleton
• Threemaintypesoffibersmakeup
thecytoskeleton:
• Microtubules
• thickest
• Intermediatefilaments
• Mediumsizeddiameter
• Microfilaments
• Thinnest
• alsocalledac=nfilaments
• Centrosomes
• Structurenearnucleusfromwhere
microtubulesgrow
• a“microtubule-organizingcenter”
• Inanimalcells
• Consistsoftwocentrioles
• Centrioles
• Pairedstructuresconsis=ngofnine
tripletsofmicrotubulesarranged
inaring
MicrotubulesandCellDivision
Centrosome
Microtubule
Centrioles0.25 µm
Longitudinal section of one centriole
Microtubules Cross section of the other centriole
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ExtracellularMatrix
• Mostcellssynthesizeandsecrete
materials
• thatareexternaltotheplasma
membrane
• Theseextracellularstructuresinclude:
• Cellwallsofplants
• Theextracellularmatrix(ECM)of
animalcells
• Intercellularjunc=ons
CellWallsofPlants• cellwall
• extracellularstructure
• dis=nguishesplantcellsfromanimalcells
• madeofcellulosefibers
• embeddedinotherpolysaccharidesandprotein
• protectstheplantcell,maintainsitsshape,andpreventsexcessiveuptakeofwater
• Prokaryotes,fungi,andafewpro=stsalsohavecellwalls
• Bacteria-pep=doglycan
• Fungi-chi=n
TheExtracellularMatrix(ECM)ofAnimalCells
• Extracellularmatrix(ECM)
• AnimalcellslackcellwallsbutarecoveredbyECM
• madeupofglycoproteins
• Collagen
• Proteoglycans
• fibronec=n
• Integrins
• ReceptorproteinsintheplasmamembranetowhichECMproteinsbind
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• Func=onsoftheECM:
• Support
• Anchorageandsepara=onofdifferent=ssues
• Adhesion
• Bindcellstogetherwithin=ssues
• Movement
• Guideforcellmigra=oninembryonicdevelopment
• Regula=on
• Propaga=onofexternals=mulitonucleus
ExtracellularMatrix
Fig.6-30
EXTRACELLULAR FLUIDCollagen
Fibronectin
Plasma membrane
Micro- filaments
CYTOPLASM
Integrins
Proteoglycan complex
Polysaccharide molecule
Carbo- hydrates
Core protein
Proteoglycan molecule
Proteoglycan complex
IntercellularJunc=ons
• Intercellularjunc=ons
• facilitatecontactbetweenneighboringcellsin=ssues,organs,ororgan
systems
• adhere,interact,andcommunicatethroughdirectphysicalcontact
• Types
• Plasmodesmata
• Plantsonly
• Tightjunc=ons
• Desmosomes
• Gapjunc=ons
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PlasmodesmatainPlantCells
• Plasmodesmata
• channelsthatperforateplantcellwalls
• waterandsmallsolutes
• some=mesproteinsandRNA
• canpassfromcelltocell
• Plasmamembranecon=nuous
• fromonecelltoanother
Fig.6-31
Interior of cell
Interior of cell
0.5 µm Plasmodesmata Plasma membranes
Cell walls
TightJunc=ons,Desmosomes,andGapJunc=ons• =ghtjunc=ons
• Leak-proofbarrier
• Plasmamembranessqueezedtogether
• Diges=vesystem
• Desmosomes
• anchoringjunc=onsfastencellstogetherintostrongsheets
• rivets
• Gapjunc=ons
• communica=ngjunc=onsprovidecytoplasmicchannelsbetweenadjacentcells
Tight junctions prevent fluid from moving across a layer of cells
Tight junction
Intermediate filaments
Desmosome
Gap junctions
Extracellular matrixSpace
between cells
Plasma membranes of adjacent cells
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Youshouldnowbeableto:1. Dis=nguishbetweenthefollowingpairsofterms:magnifica=onand
resolu=on;prokaryo=candeukaryo=ccell;freeandboundribosomes;smoothandroughER
2. Describethestructureandfunc=onofthecomponentsoftheendomembranesystem
3. Brieflyexplaintheroleofmitochondria,chloroplasts,andperoxisomes
4. Describethefunc=onsofthecytoskeleton
5. Comparethestructureandfunc=onsofmicrotubules,microfilaments,andintermediatefilaments
6. Explainhowtheultrastructureofciliaandflagellarelatetotheirfunc=ons
7. Describethestructureofaplantcellwall
8. Describethestructureandrolesoftheextracellularmatrixinanimalcells
9. Describefourdifferentintercellularjunc=ons