1408 TCC CHAPTER 4 CELLS

Introduction CellsontheMoveChapter4 Cells thesimplestcollectionofmatterthatcanlive werefirstobservedbyRobertHookein1665AntonivanLeeuwenhoeklaterdescribedcellsthatcouldmoveHeviewedbacteriawithhisownhand craftedmicroscopes Copyright 2009PearsonEducation Inc Introduction CellsontheMove Althoughcellmovementattractedtheearlyscientists weknowtodaythatnotallcellsmoveHowever thecellularpartsareactivelymovingCellsaredynamic moving livingsystems TheearlymicroscopesprovideddatatoestablishthecelltheoryThatis alllivingthingsarecomposedofcellsandthatallcellscomefromothercells CellTheory Enlargesimageformedbyobjectivelens Magnifiesspecimen formingprimaryimage Eyepiece Focuseslightthroughspecimen Ocularlens Specimen Objectivelens Condenserlens Lightsource 4 1Microscopesrevealtheworldofthecell MicroscopeshavelimitationsBoththehumaneyeandthemicroscopehavelimitsofresolution theabilitytodistinguishbetweensmallstructuresTherefore thelightmicroscopecannotprovidethedetailsofasmallcell sstructure Copyright 2009PearsonEducation Inc 4 1Microscopesrevealtheworldofthecell Biologistsoftenuseaverypowerfulmicroscopecalledtheelectronmicroscope EM toviewtheultrastructureofcellsItcanresolvebiologicalstructuresassmallas2nanometersandcanmagnifyupto100 000timesInsteadoflight theEMusesabeamofelectronsScanningElectronMicroscope 3DSurfaceImage Copyright 2009PearsonEducation Inc Humanheight Lengthofsomenerveandmusclecells 10m Frogegg Chickenegg Unaidedeye 1m 100mm 10cm 10mm 1cm 1mm Lightmicroscope Electronmicroscope 100nm 100 m 10 m 1 m Mostplantandanimalcells Viruses NucleusMostbacteriaMitochondrion 10nm Lipids Ribosome Proteins Mycoplasmas smallestbacteria 1nm Smallmolecules 0 1nm Atoms 4 2Mostcellsaremicroscopic Thesurfaceareaofacellisimportantforcarryingoutthecell sfunctions suchasacquiringadequatenutrientsandoxygenAsmallcellhasmoresurfacearearelativetoitscellvolumeandismoreefficient Copyright 2009PearsonEducation Inc 30 m 30 m 10 m 10 m Surfaceareaofonelargecube 5 400 m2 Totalsurfaceareaof27smallcubes 16 200 m2 4 3Prokaryoticcellsarestructurallysimplerthaneukaryoticcells BacteriaandarchaeaareprokaryoticcellsAllotherformsoflifeareeukaryoticcellsBothprokaryoticandeukaryoticcellshaveaplasmamembraneandoneormorechromosomesandribosomesEukaryoticcellshaveamembrane boundnucleusandanumberofotherorganelles whereasprokaryoteshaveanucleoidandnotrueorganelles Copyright 2009PearsonEducation Inc Nucleoid Ribosomes Plasmamembrane Cellwall Capsule Flagella Bacterialchromosome Atypicalrod shapedbacterium Pili AthinsectionthroughthebacteriumBacilluscoagulans TEM 4 4Eukaryoticcellsarepartitionedintofunctionalcompartments TherearefourlifeprocessesineukaryoticcellsthatdependuponstructuresandorganellesManufacturingBreakdownofmoleculesEnergyprocessingStructuralsupport movement andcommunication Copyright 2009PearsonEducation Inc 4 4Eukaryoticcellsarepartitionedintofunctionalcompartments Manufacturinginvolvesthenucleus ribosomes endoplasmicreticulum andGolgiapparatusManufactureofaprotein perhapsanenzyme mayinvolveallofthese Copyright 2009PearsonEducation Inc Smoothendoplasmicreticulum Roughendoplasmicreticulum CYTOSKELETON NUCLEUS Nuclearenvelope Chromosomes Nucleolus Ribosomes Golgiapparatus Plasmamembrane Mitochondrion Peroxisome Centriole Lysosome Microtubule Intermediatefilament Microfilament Smoothendoplasmicreticulum Roughendoplasmicreticulum CYTOSKELETON NUCLEUS Nuclearenvelope Chromosome Nucleolus Ribosomes Golgiapparatus Plasmamembrane Mitochondrion Peroxisome Cellwall Centralvacuole Microtubule Intermediatefilament Microfilament Cellwallofadjacentcell Chloroplast Plasmodesmata 4 5Thestructureofmembranescorrelateswiththeirfunctions Theplasmamembranecontrolsthemovementofmoleculesintoandoutofthecell atraitcalledselectivepermeabilityThestructureofthemembranewithitscomponentmoleculesisresponsibleforthischaracteristicMembranesaremadeoflipids proteins andsomecarbohydrate butthemostabundantlipidsarephospholipids Copyright 2009PearsonEducation Inc Hydrophilichead Hydrophobictails Symbol Phosphategroup 4 5Thestructureofmembranescorrelateswiththeirfunctions Phospholipidsformatwo layersheetcalledaphospholipidbilayerHydrophilicheadsfaceoutward andhydrophobictailspointinwardThus hydrophilicheadsareexposedtowater whilehydrophobictailsareshieldedfromwaterProteinsareattachedtothesurface andsomeareembeddedintothephospholipidbilayer Copyright 2009PearsonEducation Inc Hydrophilicheads Hydrophobictails Proteins Hydrophobicregionofprotein Insidecell Hydrophilicregionofprotein Outsidecell 4 6Thenucleusisthecell sgeneticcontrolcenter Thenucleuscontrolsthecell sactivitiesandisresponsibleforinheritanceInsideisacomplexofproteinsandDNAcalledchromatin whichmakesupthecell schromosomesDNAiscopiedwithinthenucleuspriortocelldivisionChromosomes Copyright 2009PearsonEducation Inc 4 6Thenucleusisthecell sgeneticcontrolcenter ThenuclearenvelopeisadoublemembranewithporesthatallowmaterialtoflowinandoutofthenucleusItisattachedtoanetworkofcellularmembranescalledtheendoplasmicreticulumNucleolus Granularstructure ribosomalRNA Copyright 2009PearsonEducation Inc Twomembranesofnuclearenvelope Nucleus Nucleolus Chromatin Pore Endoplasmicreticulum Ribosomes 4 7Ribosomesmakeproteinsforuseinthecellandexport Ribosomesareinvolvedinthecell sproteinsynthesisRibosomesaresynthesizedinthenucleolus whichisfoundinthenucleusCellsthatmustsynthesizelargeamountsofproteinhavealargenumberofribosomes Copyright 2009PearsonEducation Inc 4 7Ribosomesmakeproteinsforuseinthecellandexport Someribosomesarefreeribosomes othersareboundFreeribosomesaresuspendedinthecytoplasmBoundribosomesareattachedtotheendoplasmicreticulum ER associatedwiththenuclearenvelope Copyright 2009PearsonEducation Inc Cytoplasm Endoplasmicreticulum ER Freeribosomes Boundribosomes Ribosomes ER Smallsubunit Diagramofaribosome TEMshowingERandribosomes Largesubunit 4 8Overview Manycellorganellesareconnectedthroughtheendomembranesystem ThemembraneswithinaeukaryoticcellarephysicallyconnectedandcomposetheendomembranesystemTheendomembranesystemincludesthenuclearenvelope endoplasmicreticulum ER Golgiapparatus lysosomes vacuoles andtheplasmamembrane Copyright 2009PearsonEducation Inc 4 8Overview Manycellorganellesareconnectedthroughtheendomembranesystem SomecomponentsoftheendomembranesystemareabletocommunicatewithotherswithformationandtransferofsmallmembranesegmentscalledvesiclesOneimportantresultofcommunicationisthesynthesis storage andexportofmolecules Copyright 2009PearsonEducation Inc 4 9Theendoplasmicreticulumisabiosyntheticfactory Therearetwokindsofendoplasmicreticulum smoothandroughSmoothERlacksattachedribosomesRoughERlinestheoutersurfaceofmembranesTheydifferinstructureandfunctionHowever theyareconnected Copyright 2009PearsonEducation Inc SmoothER Nuclearenvelope Ribosomes RoughER 4 9Theendoplasmicreticulumisabiosyntheticfactory SmoothERisinvolvedinavarietyofdiversemetabolicprocessesForexample enzymesofthesmoothERareinvolvedinthesynthesisoflipids oils phospholipids andsteroidsDetoxification Copyright 2009PearsonEducation Inc RoughERmakesadditionalmembraneforitselfandproteinsdestinedforsecretionOnceproteinsaresynthesized theyaretransportedinvesiclestootherpartsoftheendomembranesystem Transportvesiclebudsoff Secretoryproteininsidetrans portvesicle Glycoprotein Polypeptide Ribosome Sugarchain RoughER 1 2 3 4 4 10TheGolgiapparatusfinishes sorts andshipscellproducts TheGolgiapparatusfunctionsinconjunctionwiththeERbymodifyingproductsoftheERProductstravelintransportvesiclesfromtheERtotheGolgiapparatusModification packagingandtransportofproductsOnesideoftheGolgiapparatusfunctionsasareceivingdockfortheproductandtheotherasashippingdockProductsaremodifiedastheygofromonesideoftheGolgiapparatustotheotherandtravelinvesiclestoothersites Copyright 2009PearsonEducation Inc Golgiapparatus Golgiapparatus Receiving sideofGolgiapparatus TransportvesiclefromER Newvesicleforming Shipping sideofGolgiapparatus TransportvesiclefromtheGolgi 4 11Lysosomesaredigestivecompartmentswithinacell AlysosomeisamembranoussaccontainingdigestiveenzymesTheenzymesandmembraneareproducedbytheERandtransferredtotheGolgiapparatusforprocessingThemembraneservestosafelyisolatethesepotentenzymesfromtherestofthecellDigestion recyclecellstructures Copyright 2009PearsonEducation Inc 4 11Lysosomesaredigestivecompartmentswithinacell OneoftheseveralfunctionsoflysosomesistoremoveorrecycledamagedpartsofacellThedamagedorganelleisfirstenclosedinamembranevesicleThenalysosomefuseswiththevesicle dismantlingitscontentsandbreakingdownthedamagedorganelle Copyright 2009PearsonEducation Inc Animation LysosomeFormation Digestiveenzymes Lysosome Plasmamembrane Foodvacuole Digestion Lysosome Vesiclecontainingdamagedmitochondrion Digestion 4 12Vacuolesfunctioninthegeneralmaintenanceofthecell VacuolesaremembranoussacsthatarefoundinavarietyofcellsandpossessanassortmentoffunctionsExamplesarethecentralvacuoleinplantswithstoragefunctions involvedwithgrowth protectionPigmentvacuolesinplantstoprovidecolortoflowersContractilevacuolesinsomeprotiststoexpelwaterfromthecellFoodvacuoles Copyright 2009PearsonEducation Inc Video ParameciumVacuole Nucleus Chloroplast Centralvacuole Nucleus Contractilevacuoles Nucleus Vacuole Lysosome Plasmamembrane SmoothER Nuclearmembrane Golgiapparatus RoughER Transportvesicle Transportvesicle 4 14Mitochondriaharvestchemicalenergyfromfood CellularrespirationisaccomplishedinthemitochondriaofeukaryoticcellsCellularrespirationinvolvesconversionofchemicalenergyinfoodstochemicalenergyinATP adenosinetriphosphate MitochondriahavetwointernalcompartmentsTheintermembranespace whichenclosesthemitochondrialmatrixwherematerialsnecessaryforATPgenerationarefound Copyright 2009PearsonEducation Inc Mitochondrion Intermembranespace Innermembrane Cristae Matrix Outermembrane 4 15Chloroplastsconvertsolarenergytochemicalenergy ChloroplastsarethephotosynthesizingorganellesofplantsPhotosynthesisistheconversionoflightenergytochemicalenergyofsugarmoleculesChloroplastsarepartitionedintocompartmentsTheimportantpartsofchloroplastsarethestroma thylakoids andgrana Copyright 2009PearsonEducation Inc Chloroplast Stroma Innerandoutermembranes Granum Intermembranespace 4 16EVOLUTIONCONNECTION Mitochondriaandchloroplastsevolvedbyendosymbiosis Whencompared youfindthatmitochondriaandchloroplastshave 1 DNAand 2 ribosomesThestructureofbothDNAandribosomesisverysimilartothatfoundinprokaryoticcells andmitochondriaandchloroplastsreplicatemuchlikeprokaryotesThehypothesisofendosymbiosisproposesthatmitochondriaandchloroplastswereformerlysmallprokaryotesthatbeganlivingwithinlargercellsSymbiosisbenefitedbothcelltypes Copyright 2009PearsonEducation Inc Engulfingofphotosyntheticprokaryote Chloroplast Mitochondrion Somecells Hostcell Mitochondrion Hostcell Engulfingofaerobicprokaryote 4 17Thecell sinternalskeletonhelpsorganizeitsstructureandactivities Cellscontainanetworkofproteinfibers calledthecytoskeleton thatfunctionsincellstructuralsupportandmotilityScientistsbelievethatmotilityandcellularregulationresultwhenthecytoskeletoninteractswithproteinscalledmotorproteins Copyright 2009PearsonEducation Inc Video CytoplasmicStreaming Vesicle ATP Receptorformotorprotein Microtubuleofcytoskeleton Motorprotein ATPpowered a Microtubule Vesicles b 0 25 m 4 17Thecell sinternalskeletonhelpsorganizeitsstructureandactivities ThecytoskeletoniscomposedofthreekindsoffibersMicrofilaments actinfilaments supportthecell sshapeandareinvolvedinmotilityIntermediatefilamentsreinforcecellshapeandanchororganellesMicrotubules madeoftubulin shapethecellandactastracksformotorprotein Copyright 2009PearsonEducation Inc Microfilament Actinsubunit 7nm Intermediatefilament Fibroussubunits 10nm Microtubule Tubulinsubunit 25nm Nucleus Nucleus 4 18Ciliaandflagellamovewhenmicrotubulesbend Whilesomeprotistshaveflagellaandciliathatareimportantinlocomotion somecellsofmulticellularorganismshavethemfordifferentreasonsCellsthatsweepmucusoutofourlungshaveciliaAnimalspermareflagellated Copyright 2009PearsonEducation Inc Video ParameciumCilia Video Chlamydomonas Cilia Flagellum 4 18Ciliaandflagellamovewhenmicrotubulesbend Aflagellumpropelsacellbyanundulating whiplikemotionCilia however workmoreliketheoarsofacrewboatAlthoughdifferencesexist flagellaandciliahaveacommonstructureandmechanismofmovement Copyright 2009PearsonEducation Inc 4 18Ciliaandflagellamovewhenmicrotubulesbend BothflagellaandciliaaremadeofmicrotubuleswrappedinanextensionoftheplasmamembraneAringofninemicrotubuledoubletssurroundsacentralpairofmicrotubulesThisarrangementiscalledthe9 2patternandisanchoredinabasalbodywithninemicrotubuletripletsarrangedinaring Copyright 2009PearsonEducation Inc Animation CiliaandFlagella Centralmicrotubules Outermicrotubuledoublet Radialspoke Dyneinarms Plasmamembrane Triplet Crosssections Flagellum Basalbody Basalbody 4 20Theextracellularmatrixofanimalcellsfunctionsinsupport