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1、Copyright©2008PearsonEducation,Inc.,publishingasPearsonBenjaminCummingsPowerPoint®LecturePresentationsforBiologyEighthEditionNeilCampbellandJaneReeceLecturesbyChrisRomero,updatedbyErinBarleywithcontributionsfromJoanSharpChapter12TheCellCycleOverview:TheKeyRolesofCellDivis
2、ion•Theabilityoforganismstoreproducebestdistinguisheslivingthingsfromnonlivingmatter•Thecontinuityoflifeisbasedonthereproductionofcells,orcelldivisionCopyright©2008PearsonEducation,Inc.,publishingasPearsonBenjaminCummings•Inunicellularorganisms,divisionofonecellreproduces
3、theentireorganism•Multicellularorganismsdependoncelldivisionfor:–Developmentfromafertilizedcell–Growth–Repair•Celldivisionisanintegralpartofthecellcycle,thelifeofacellfromformationtoitsowndivisionCopyright©2008PearsonEducation,Inc.,publishingasPearsonBenjaminCummingsFig.1
4、2-2100µm200µm20µm(a)Reproduction(b)Growthanddevelopment(c)TissuerenewalThefunctionsofcelldivisionConcept12.1:Celldivisionresultsingeneticallyidenticaldaughtercells•Mostcelldivisionresultsindaughtercellswithidenticalgeneticinformation,DNA•Aspecialtypeofdivisionproducesnoni
5、denticaldaughtercells(gametes,orspermandeggcells)Copyright©2008PearsonEducation,Inc.,publishingasPearsonBenjaminCummingsCellularOrganizationoftheGeneticMaterial•AlltheDNAinacellconstitutesthecell’sgenome•AgenomecanconsistofasingleDNAmolecule(commoninprokaryoticcells)oranu
6、mberofDNAmolecules(commonineukaryoticcells)•DNAmoleculesinacellarepackagedintochromosomesCopyright©2008PearsonEducation,Inc.,publishingasPearsonBenjaminCummingsFig.12-3Eukaryoticchromosomes20µm•Everyeukaryoticspecieshasacharacteristicnumberofchromosomesineachcellnucleus•S
7、omaticcells(nonreproductivecells)havetwosetsofchromosomes•Gametes(reproductivecells:spermandeggs)havehalfasmanychromosomesassomaticcells•Eukaryoticchromosomesconsistofchromatin,acomplexofDNAandproteinthatcondensesduringcelldivisionCopyright©2008PearsonEducation,Inc.,publi
8、shingasPearsonBenjaminCummingsDistributionofChromosomesDuringEukaryoticCellDivision•Inpreparatio
