预览加载中，请您耐心等待几秒...

5.1《细胞增殖》素材02（苏教版必修1）.doc

预览
1/4
2/4
3/4
4/4

在线预览结束，喜欢就下载吧，查找使用更方便

下载提示 文本预览

如果您无法下载资料，请参考说明：

1、部分资料下载需要金币，请确保您的账户上有足够的金币

2、已购买过的文档，再次下载不重复扣费

3、资料包下载后请先用软件解压，在使用对应软件打开

5.1《细胞增殖》素材02（苏教版必修1） 有丝分裂英文版介绍(Mitosis) Mitosisistheprocessinwhichaeukaryoticcellseparatesthechromosomesinitscellnucleus,intotwoidenticalsetsintwodaughternuclei.Itisgenerallyfollowedimmediatelybycytokinesis,whichdividesthenuclei,cytoplasm,organellesandcellmembraneintotwodaughtercellscontainingroughlyequalsharesofthesecellularcomponents.Mitosisandcytokinesistogetherdefinethemitotic(M)phaseofthecellcycle-thedivisionofthemothercellintotwodaughtercells,geneticallyidenticaltoeachotherandtotheirparentcell.Mitosisdividesthechromosomes Mitosisoccursexclusivelyineukaryoticcells,butoccursindifferentwaysindifferentspecies.Forexample,animalsundergoan"open"mitosis,wherethenuclearenvelopebreaksdownbeforethechromosomesseparate,whilefungisuchasAspergillusnidulansandSaccharomycescerevisiae(yeast)undergoa"closed"mitosis,wherechromosomesdividewithinanintactcellnucleus.Prokaryoticcells,whichlackanucleus,dividebyaprocesscalledbinaryfission. Theprocessofmitosisiscomplexandhighlyregulated.Thesequenceofeventsisdividedintophases,correspondingtothecompletionofonesetofactivitiesandthestartofthenext.Thesestagesareprophase,prometaphase,metaphase,anaphaseandtelophase.Duringtheprocessofmitosisthepairsofchromosomescondenseandattachtofibersthatpullthesisterchromatidstooppositesidesofthecell.Thecellthendividesincytokinesis,toproducetwoidenticaldaughtercells. Becausecytokinesisusuallyoccursinconjunctionwithmitosis,"mitosis"isoftenusedinterchangeablywith"mitoticphase".However,therearemanycellswheremitosisandcytokinesisoccurseparately,formingsinglecellswithmultiplenuclei.Thisoccursmostnotablyamongthefungiandslimemoulds,butisfoundinvariousdifferentgroups.Eveninanimals,cytokinesisandmitosismayoccurindependently,forinstanceduringcertainstagesoffruitflyembryonicdevelopment.Errorsinmitosiscaneitherkillacellthroughapoptosisorcausemutationsthatmayleadtocancer. Phasesofcellcycleandmitosis Interphase Themitoticphaseisarelativelyshortperiodofthecellcycle.Italternateswiththemuchlongerinterphase,wherethecellprep