課件文稿教案ap-biology

AAPBiologychapterCellGGoingfromeggtotheoriginalfertilizedegghastoandCCellDivisionEverycellfromaCelldivisionisthereproductionofCelldivisionisonlyasmallpartofthelifecycleofaCCellCellcycle細胞周期isthelifecycleofcellfromthebeginningofonedivisiontothebeginningofthenext.CellcycleisdividedintotwoMostofthelifeofacellisspentinIInterphase:thegrowingInterphaseisthetimespanfromonecelldivisiontoAllproteinsandenzymesitneedstogrowareproducedduringinterphase.IInterphasecanbedividedintothreestages:G1,G2,andSG1=1stGap ngits“everydayjob”cellgrowsS=DNAcopiesG2=2ndGappreparesforcellgrowsproducesorganelles,proteins,GG1andG2"G"standsfor"gap"orDuringthesestages,thecellproducesproteinsandenzymesforgrowthandpreparationformitosis.SSphase---SynthesisSphaseisthemostimportantphase,whenthecellreplicatesitsgeneticmaterial.DuplicateallofitsTTheoriginalchromosomeanditsduplicatearelinkedtogethertoformsisterchromatids姐妹染色單體eachindividualstructureiscalledachromatid染Thechromatidaretogetherbyastructure著著絲Oncethechromosomehavereplicated,thecellisreadytobeginmitosis,whichistheperiodwhenthecelldivides.four, SStage1:ThefirstsignsofprophaseisthedisappearanceoftheThechromosomesthicken,formingcoilsuponcoils,and visible(thechromosomesarenotvisibleduringinterphase).Thegeneticmaterialisscatteredthroughoutthenucleusandcalledchromatin染色質(zhì)SStage1:centrioles中心粒foundwithinmicrotubuleorganizingcenters(MTOCs)startstomoveawayfromeachother,towardoppositeendsofthecell.Thecentrioleswillspinoutasystemofmicrotubulesknownasthespindlefibers紡錘絲Thesespindlefiberswillattachtoastructureoneachchromatidcalledakinetochore著絲（紡錘絲SStage2:Thechromosomesbegintolineupalongtheequatorialne赤道板,orthemetaphase Thespindlefibersareattachedtothekinetochoreofthechromatid.SStage3:Thesisterchromatidsofeachchromosomeseparateatthecentromereandmigratetoopppositepoles.Thechromatidsarepulledapartbyspindle,whichbegintoshorten.EachhalfofapairofsisterchromatidsmovesoppositepolesoftheNonkinetochoremicrotubuleselongatetheSStageItisthefinalphaseofAnuclearmembraneformsaroundeachsetofandthenucleolithecellbegintosplitalongacleavageCytokinesisistheprocessetosplitthe溝sm,Thecellmembraneformabouteachcellandthesplitintotwodistinctdaughtercells.CCytokinesisinMMitosisntInprophase,thereisnocentriolesin ntcellsandthespindles紡錘體spinoutfiberscalledspindlesfibers. ntcellsform teinthemiddle ophase,cytokinesisoccursdifferently MitosisIisforPisforMisforAisforTisforPPurposeofTOproducedaughtercellsthatareidenticalcopiesoftheparentcell.TOmaintainthepropernumberofchromosomesfromgenerationtogeneration.Mitosisoccursinjustabouteverycellexcept00FFrequencyofcellFrequencyofcelldivisionvariesbycellcellcycle<20skindividefrequentlythroughoutlife12-24hourscycleliverretainabilitytodivide,butkeepitindivideonceeveryyearormaturenervecells&muscledonotdivideatallafterOOverviewofCellCycleTwoirreversiblepointsincellcyclereplicationofgeneticmaterialseparationofsisterchromatidsprocessisassessed&possiblysisterCCheckpointcontrolcellcyclecontrolledbySTOP&GOchemicalsignalsatcriticalsignalsindicateifkeycellularprocesseshavebeencompletedcorrectlyCCheckpointcontrol3majorcanDNAsynthesishasDNAsynthesisbeencompletedcorrectly?commitmenttomitosisspindlecheckpointareallchromosomesattachedcansisterchromatidsseparateGG1/SG1/Scheckpointismostprimarydecisionpoint“restrictionpoint”ifcellreceives“GO”signal,itinternalsignals:cellgrowth(size),cellexternalsignals:“growthfactors”ifcelldoesnotreceivesignal,itexitscycleswitchestoG0non-dividing,workingCCancer&CellCancerisessentiallyafailureofcelldivisioncontrolWhatcontrolislosecheckpointHHaploidsVsEveryorganismhasacertainnumberofonesetfromeachparent,andacellthathasbothsetsMosteukaryoticcellshavetwofullsetsofchromosomesisadiploid二倍體cellgivingchromosomenumberas"2n".cellgivingthesymbolAcellhasonlyonesetofchromosomesisahaploid單nHumanHumancellshave46Humanchromosomescomeinpairscalledhomologues同源體.46chromosomesareacuallyonly23distinctThehoumologouschromosomeswhichmakeupeacharesimilarinsizeandshapeandexpresssimilarsingle-double-44623Therearespecialcellsinhumanbodyarehaploid,andcellsarecellsorgametes配子Anoffspringhasonesetofchromosomesfromeachofitsparents.Soaparentcontributesagametewithonesetthatwillbepairedwiththesetfromtheotherparenttoproduceanewdiploidcell,orazygote合子.istheproductionofandislimitedcellsinInmales,thegonadsare,whilefemalestheyarethecellsproducehaploidcells(n),whichthentorestorethediploid(2n)numberduring..TheseroundsofcelldivisioncalledmeiosisIandmeiosisII.mmeiosisFourprophaseI,metaphaseI,anaphaseI, ophasePProphaseAsinmitosis,thenuclearmembranedisappears,thechromosomes evisible,andthecentriolesmovetooppositepolesofthenucleus.Differently,thechromosomeslineupside-by-sidewiththeircounterparts(homologues),knowingas同源同源SynapsisinvolvestwosetsofchromosomesthatcomeSynapsisinvolvestwosetsofchromosomesthatcometogethertoformatetrad四分體(orabivalentconsistingoffourchromatids.Synapsisisfollowedbycrossing-over,theexchangesegmentsbetweenhomologous"pieces""pieces"chromosomesareexchangedbetweenhomologouspartnersinprophaseBytheendofprophase,thechromosomeswillhaveexchangedregionscontainingseveralalleles等位 differentformsofthesamegene,andthehomologouschromosomesareheldtogetheronlyatspecializedregionscalledchiasmata交叉.CCrossingduringProphase1,sisterchromatidshomologouspairspiecesof–DNAbreaks&re-33crossoverre-fusingofDNANewcombinationsofMMetaphaseThetetradslineupatthemetaphase Thechromosomeslineupindividually.MMetaphaseAAnaphaseOneofeachpairofchromosomeswithinatetradseparatesandmovestooppositepoles.Thechromosomesdonotseparateatthecentromere,andtheyseparatewiththeircentromeresintact.AAnaphaseophaseophaseThenuclearmembraneformsaroundeachsetofFinally,thecellsundergocytokinesis,formingtwodaughtercells,whichcontainsthehaploidnumberofchromosomeconsistingtwosisterophaseophaseMMeiosisInprophaseII,thechromosomesonceagaincondenseandevisible.InmetaphaseII,thechromosomemovetowardmetaphasete,liningupsingleInanaphaseII,thechromatidssplitatthecentromereandarepulledtooppositeendsofthecell. ophaseII,thenuclearmembraneformsaroundeachsetofchromosomesandtotalfourhaploidcellsareMMeiosisMeiosisisalsoknownasgametogenesis配子發(fā)生Spermatogenesisisthemeiosisofproducingofspermcells,andfourspermcellsareproducedforeachdiploidcell.While,oogenesisisthemeiosisofproducinganeggcelloranovum.Oogenesisproducesonly