生物专业英语教学-细胞的繁殖

Unit3CellularReproduction:MitosisandMeiosis,WarmingupWordsandphrasesTextAnalysisSimpleexercises,Contents,Warmingup,有丝分裂:,无丝分裂:,减数分裂:,一种特殊方式的有丝分裂,细胞增殖方式,与体细胞的形成有关,不出现纺缍体，没有染色体等变化。如蛙的红细胞。,有丝分裂和减数分裂的比较,比较,有丝分裂,减数分裂,不同点,相同点,分裂后形成(),分裂后形成(),细胞分裂（）次，产生（）个子细胞,细胞分裂（）次，产生（）个子细胞,子细胞和母细胞的染色体数（）,子细胞染色体数是母细胞的（）,不出现联会、四分体现象,减数I发生同源染色体的联会、四分体现象,细胞分裂过程中均出现（）和（），染色体复制（）次,体细胞,生殖细胞,1,2,2,4,相同,一半,染色体,纺锤体,1,1.interphasen.分裂间期,int(:)feiz,Interphase-ThestageintheCELLCYCLEwhenthenucleusisnotinastateofdivision.Interphaseisdivisibleintovariousstageseachcharacterizedbyadifferingphysiologicalactivity.,间期：是细胞周期的一个时期，在这个时期里细胞核不分裂。根据细胞生理活性差异可以把间期分成不同的阶段。,Wordsandphrases,Cellcycle,Interphase间期:G1+S+G2Mphase(mitosis有丝分裂):,分裂间期,1、DNA复制2、中心粒复制,其中G1和G2期主要是合成有关蛋白质和RNA，S期则完成DNA的复制。,2.prophase,prufeiz,n.分裂前期,3.metaphasen.分裂中期,metfeiz,4.anaphasenfeizn.分裂后期,5.telophase,telfeiz,n.分裂末期,有丝分裂前期,1）染色体出现2）每条染色体包含兩条染色单体3）复制的中心粒向两极移动4）纺锤体出现5）染色体中部和纺锤丝相连6）核膜、核仁消失,prophase,prufeiz,n.分裂前期,Thefirststageofmitosis,duringwhichindividualchromosomesbecomevisible.,有丝分裂中期,1）中心粒到达细胞两极2）染色体排列在细胞中央的赤道板上,赤道板（equatorialplane）,3.metaphasen.分裂中期,metfeiz,Thesecondstageinmitosis,duringwhichthechromosomesalignattheequatorialplane.,1）着丝粒分裂，染色单体分离2）两条染色体受纺锤丝牵引，向细胞两极移动,有丝分裂后期,4.anaphasenfeizn.分裂后期,Thethirdstageofmitosis,duringwhichthecentromeressplitandthechromosomesmovetothepoles.,1）细胞质分裂2）赤道板附近的细胞膜凹陷3）细胞一分为二4）植物则是在细胞中央形成细胞板，再形成细胞壁,中央凹陷,5.telophase,telfeiz,n.分裂末期,有丝分裂末期,Thelaststageinmitosis,duringwhichdaughternucleiareformed.,有丝分裂全过程,interphase,prophase,metaphase,anaphase,telophase,prometaphase,Duringmitosis,sisterchromatidsremainjoinedbytheircentromereuntilanaphase.,在有丝分裂期间，姐妹染色单体在分裂后期之前都是通过着丝点连接的。,Forexample：,Aplantcellstructurethatbeginstoforminthecenterofthecellandproceedstothecellmembrane,resultingincytokinesis.,6.Cellplate,n.细胞板,Thecell-platemembraneseventuallyformthetwonewplasmamembranesofthedaughtercells.,Forexample：,细胞板的膜最终形成两个新的子细胞的质膜。,7.centromeren.着丝粒;着丝点,sentr,mi,Thesmallareaofachromosomethatdoesnotstainwithbasicdyes(碱性燃料)duringmitosisandmeiosis;atinterphaseitissinglewhiletherestofthechromosomeismadeupoftwochromatids.,8.chalonen.抑素,klun,9.chromatidn.染色单体,krumtid,Areplicatedchromosomephysicallyattachedtoanidenticalchromatidatcentromere.,一对同源染色体（含4条染色单体）,一条染色单体,10.chromatinn.染色质,krumtin,Chromatinisthematerialthatmakesupchromosomes;itconsistsofDNAcomplexedwithproteins.,由DNA和蛋白质组成的染色质，是构成染色体的原料。,11.cytokinesisn.胞质分裂,saitukaini:sis,Division（mitosisormeiosis)ofthecytoplasmofonecellintotwonewcells.,12.diploidn.二倍体,diplid,Anynucleus,cell,ororganismthatposessestwicethehaploidnumberofchromosomes.Duringtheprocessoffertilizationazygotewiththediploidsetisproduced.,通过受精作用使受精卵形成一个二倍体。,13.haploidn.单倍体,hplid,Genome-Acompletehaploidchromosomeset.基因组：即一套完整的单倍体染色体。,Anynucleus,cell,ororganismthatposessestwiceasinglesetofunpairedchromosome.,14.histonen.组蛋白,histun,Thesmallproteinshavefivefamiliesorclasses:H1,H2A,H2B,H3,H4;andhavealargepositivecharge(richinLys、Arg)whichcanbindverystronglytothenegtivelychargedDNAinformingchromatin.,DNA和组蛋白组装成的结构叫做染色体。,15.homologouspairhumlgspn.同源染色体对,一对同源染色体（含4条染色单体）,一条染色单体,16.karyotypen.核型，染色体组型,kritaip,Theappearanceofthechromosomecomplementofanorganismorcell.核型：一个给定物种的染色体所表现出的物理学特征。,17.meiosisn.减数分裂,maiusis,Theprocessbywhichanucleusdividesintofourdaughternuclei,eachcontaininghalfthenumberofchromosomesoftheparentnucleus.,18.mitosis,mitusis,n.有丝分裂,间接核分裂,通过有丝分裂，每条染色体精确复制成的两条染色单体并均等地分到两个子细胞，使子细胞含有同母细胞相同的遗传信息。细胞有丝分裂过程，可以区分为：前期，中期，后期和末期。,有丝分裂和减数分裂的比较,比较,有丝分裂,减数分裂,不同点,相同点,分裂后形成(),分裂后形成(),细胞分裂（）次，产生（）个子细胞,细胞分裂（）次，产生（）个子细胞,子细胞和母细胞的染色体数（）,子细胞染色体数是母细胞的（）,不出现联会、四分体现象,减数I发生同源染色体的联会、四分体现象,细胞分裂过程中均出现（）和（），染色体复制（）次,体细胞,生殖细胞,1,2,2,4,相同,一半,染色体,纺锤体,1,19.metaphaseplate,n.中期板，赤道板,赤道板（equatorialplane）,20.nucleosome,nju:klisum,n.生化核小体,Thebasicunitofchromatinstructureineukaryoticcells.Anucleosomeconsistsof8histonemolecules,togetherwithabout140basepairsofDNAcoiledaroundit.,Nucleosomeisthebasicunitofchromatinstructure,21.spindle,spindl,n.纺锤体,Anarrayofmicrotubuleextendingfrompoletppoleandusedinthemovementofchromosomes.,Reviewing,1.anaphasen.分裂后期2.Cellplaten.细胞板3.centromeren.着丝粒4.chalonen.抑素5.chromatidn.染色单体6.chromatinn.染色质7.cytokinesisn.胞质分裂8.diploidn.二倍体9.haploidn.单倍体10.histonen.组蛋白11.Homologouspairn.同源染色体对,nfez,sentrmi,kln;ke-,krmtd,krmtn,satokniss,12.interphasen.分裂间期13.karyotypen.核型，染色体组型14.meiosisn.减数分裂15.Metaphasen.中期16.metaphaseplaten.中期板，赤道板17.mitosisn.有丝分裂18.nucleosomen.核小体19.prophasen.前期20.spindlen.纺锤体21.telophasen.末期,kr,tap,Pre-readingActivities:Listentoavideoandthinkabouttheconceptandmechanismofcellreproduction.Textanalysis,TextAnalysis,TextAnalysis,1.Thenucleusandchromosomes,Thecellnucleusisthemainrepositoryofgeneticinformation.Withinthenucleusarethechromosomes-tightlycoiledstrandsofDNAandclustersofassociatedproteins.,细胞核是遗传信息的主要贮存室。细胞核内部是染色体，包括紧密缠绕的线状DNA和与之相连的蛋白质串。,LongstretchesofthecontinuousDNAmoleculewindaroundtheseclustersofproteins,orhistones,formingbeadlikecomplexesknownasnucleosomes.,长的伸展的持续的DNA分子围绕蛋白质串（组蛋白）缠绕，形成串珠状的复合体，被称为核小体。,Morecoilingandsupercoilingproducesadensechromosomestructure.EachlongstrandofDNAcombineswithhistonesandnonhistoneproteinstomakeupthesubstancechromatin.,更多的螺旋或超螺旋形成一个密集的染色体结构。每一个DNA长链与组蛋白或非组蛋白结合构成了染色质。,Apictorialdisplayofanorganismschromosomesinthecoiled,condensedstateisknownasakaryotype.,有机体的染色体以螺旋的、浓缩的状态用图示的方式展示出来，称为染色体组型.,Karyotypesrevealthatinmostcellsallbutsexchromosomesarepresentastwocopies,referredtoashomologouspairs.,染色体组型显示出大多数细胞除了性染色体以外的其他染色体以2个拷贝的形式存在，被称为同源染色体对。,Non-sexchromosomesarecalledautosomes.Organismswhosecellscontaintwosetsofparentalchromosomesarecalleddiploid;thosewithcellscontainingasinglesetofparentalchromosomesarecalledhaploid.,非性染色体称为常染色体。细胞中含有两套亲本染色体的有机体称为二倍体；细胞中含有一套亲本染色体的有机体称为单倍体。,2Thecellcycle,Thecellcycleisaregularsequenceinwhichthecellgrows,preparesfordivision,anddividestoformtwodaughtercells,eachofwhichthenrepeatsthecycle.,细胞周期是一个有顺序的过程：细胞生长、准备分裂、分裂形成两个子细胞，每个子细胞再重新开始细胞周期。,Suchcyclingineffectmakessingle-celledorganismsimmortal.Manycellsinmulticellularorganisms,includinganimalmuscleandnervecells,eitherslowthecycleorbreakoutofitaltogether.,这种有效的循环使得单细胞生物永生。多细胞生物的许多细胞包括动物肌肉和神经细胞能够使细胞周期时间延长或完全脱离细胞周期。,Thenormalcellcycleconsistsoffourphases.ThefirstthreeincludeG1,theperiodofnormalmetabolism;Sphase,duringwhichnormalsynthesisofbiologicalmoleculescontinues,DNAisreplicated,andhistonesaresynthesized;,正常的细胞周期由四个阶段构成。前三个阶段包括G1，即正常的代谢的阶段；S期，期间持续进行生物分子的正常合成，即DNA复制和组蛋白的合成；,andG2,abriefperiodofmetabolismandadditionalgrowth.TogethertheG1,S,andG2phasesarecalledinterphase.,G2期（代谢和再次生长的短阶段）。G1、S和G2期合起来称为间期。,ThefourthphaseofthecellcycleisMphase,theperiodofmitosis,duringwhichthereplicatedchromosomescondenseandmoveandthecelldivides.,细胞周期的第四步为M期（进行有丝分裂的阶段），在这一阶段，复制的染色体浓缩、运动，细胞分裂。,Itisbelievedthatpropertiesofthecellcytoplasmcontrolthecellcycle,alongwithexternalstimulatorsandinhibitorssuchaschalones.,被认为是细胞质的特性和外部的刺激因子和抑制剂例如抑素控制了细胞周期。,3Mitosis:Partitioningthehereditarymaterial,Biologistsdividethemitoticcycleintofourphases.Atthebeginningofprophasethechromosomeseachconsistoftwohighlycondensedchromatidsattachedtoeachotheratacentromere.,生物学者把有丝分裂周期分为四步，分裂前期开始时，每一条染色体包括两条高度浓缩的染色单体，两者在着丝粒位置连在一起。,Asprophaseendsandmetaphasebegins,thecondensedchromosomesbecomeassociatedwiththespindle.Eventuallythechromosomesbecomearrangedinaplane(calledthemetaphaseplate)atarightangletothespindlefibers.,当前期结束时，分裂中期开始。高度浓缩的染色体与纺锤体相连，最终染色体排在一个叫做中期板的平面上，与纺锤丝成垂直角度。,Next,duringanaphase,thetwosisterchromatidsofeachchromosomessplit,andonefromeachpairdrawntowardeachpoleofthecell.,接着，在分裂后期，每个染色体上的两个姊妹染色单体分开，每一对的一个分别移向细胞的一极。,Duringtelophasenuclearenvelopesbegintoformaroundeachsetofchromosomes,anddivisionofthecytoplasmtakesplace.,在分裂末期，围绕每一套染色体开始形成核膜，然后开始细胞质的分裂。,Asmitosisproceeds,thespindlemicrotubulesplayacrucialroleinensuringthatbothpairedandseparatedchromatidsmoveintherightdirectionsatthepropertimes.,当有丝分裂进行时，纺锤体的微管在保证成对的和分离的染色单体适时向正确的方向运动起到关键作用。,Eachhalfofthespindleformsasmicrotubulesextendfromeachpoleofadividingcelltotheregionofthemetaphaseplate.,当微管从每个分裂细胞的两极延伸至赤道板时，形成了纺锤体的每一半。,Duringprophase,othermicrotubules,thecentromericfibers,extendoutwardfromthespindlepolestostructuresonthechromosomescalledkinetochores.Duringanaphasethefibersbegintoshorten,andthechromatidsbegintomoveapart.,在有丝分裂前期，另外一种微管，着丝粒纤维从纺锤体的两极向外延伸到染色体上叫做动粒的结构上。在分裂后期，纤维开始缩短，染色单体开始分开。,knitk;ka-,kinetochore,动粒,Thespindleformsdifferentlyinplantandanimalcells.Inanimalsitisassociatedwithcentriole,whileinplantandfungalcellsspindleformationisassociatedwithregionscalledmicrotubuleorganizingcenters.,在植物和动物细胞中纺锤体的形成不同，动物细胞中，与中心体有关。在植物和真菌细胞中纺锤体的形成与叫做微管组织中心的区域有关。,4Cytokinesis:Partitioningthecytoplasm,Thedivisionofthecellcytoplasmattheendofmitosisiscalledcytokinesis.Inanimalcellsittakesplaceasaringofactinfilamentscontractsaroundthecellequator,pinchingthecellintwo.,有丝分裂结束时细胞质的分裂称为胞质分裂。动物细胞中胞质分裂过程中，首先肌动蛋白形成的环在细胞赤道周围进行收缩，将细胞收缩为两部分。,Inplantcells,whichareboundedbyacellwall,cytokinesisinvolvesthebuildingofanewcellplateacrossthedividingcellatitsequator.Cellwallmaterialisthendepositedintheregionofthecellplate.,植物细胞有细胞壁包被，胞质分裂包括围绕新细胞的赤道周围形成新细胞板，然后细胞壁物质在细胞板位置沉积。,5Meiosis:Thebasisofsexualreproduction,Meiosisisaspecialformofcelldivisionthattakesplaceinthereproductiveorgansthatproducesexcells.,减数分裂是细胞分裂的特殊形式，在产生生殖细胞的生殖器官中发生。,Likemitosis,ittakesplaceafterDNAreplicationhasoccurredandinvolvestwosequentialnucleardivisions(meiosisIandmeiosisII).Thesedivisionsresultinfourdaughtercells,eachwithhalfthenumberofchromosomesoftheparentcell.,如有丝分裂，它发生于DNA复制后，包括两个有顺序的核分裂阶段（减数分裂I期和减数分裂II期）。这些分裂产生4个子细胞，每一个子细胞的染色体数是母细胞染色体数的一半。,Thephenomenonofcrossingoverduringmeiosisresultsinexchangesofgeneticinformationbetweenchromosomes.Hence,thehomologouschromosomesdistributedtodifferentprogenycellsarenotidentical.,减数分裂交叉现象的出现导致了染色体之间互换遗传信息。这样分配到不同后代细胞中的同源的染色体并不相同。,AsinmitosistwochromatidsexistforeachchromosomeatthebeginningofprophaseI.,象有丝分裂那样，在分裂前I期的开始，每个染色体含有两条染色单体。,Duringthisphasethehomologouschromosomesundergosynapsisorpairing,whichisbroughtaboutbyabridgingstructureofproteinsandRNAcalledthesynaptinemalcomplex.,在这一阶段，同源的染色体经历了联会或配对，这是由蛋白质和RNA形成的桥状结构-联会复合体的出现而发生的。,snpss,synapsis,联会,Thehomologouspairsstaytogetherwhentheyalignonthemetaphaseplate.,当同源染色体对排列于赤道板上时，（这两条染色体）同时存在。,Unliketheanaphaseofmitosis,however,duringanaphaseIthetwochromatidsofeachchromosomestayjoinedatthecentromereandmovetogethertooneofthetwopolesofthecell.,然而，与有丝分裂后期不同的是，减数分裂后期I每个染色体的两条染色单体在着丝粒处相连，一起移向细胞的一极。,Itisthiseventthatresultsinthehalvingofthechromosomenumberinthefourdaughtercellsthatresultfrommeiosis.,正是由于这一事件导致减数分裂中4个子细胞的染色体数目减半。,DuringtelophaseInuclearenvelopesenclosethechromosomesinnuclei,andinmostspeciescytokinesis(thefirstnucleardivision)follows.,在减数分裂末期I，核被膜将染色体包裹在细胞核中，接着多数种类开始胞质分裂（第一次细胞核分裂）。,ThesecondnucleardivisionbeginswithmetaphaseII,inwhichthechromosomesineachdaughtercellagainalignonametaphaseplate.,第二次细胞核分裂开始于减数分裂中期II，每个子细胞中的染色体重新排列于中期板上。,Thecenromeresfinallydivide,andeachsisterchromatidmovestooneofthepolesofthespindle.ThenextphaseistelophaseII,followedagainbycytokinesis.Theresultoftheentireprocessisfourhaploidcellsinwhichparentalchromosomesarerandomlydistributed.,着丝粒最终分裂，每个姊妹染色单体移向纺锤体的一极。下一个阶段是减数分裂末期II，然后是胞质分裂。整个过程的结果是4个单倍体细胞，亲本的染色体被随机分配。,6)Asexualversussexualreproduction,Mitosisandmeiosis,respectively,makesimplecelldivisionandsexualreproductionpossible.Eachmeansofpassingonhereditaryinformationhasadvantages.,有丝分类和减数分裂分别使简单的细胞分裂和有性生殖成为可能。每一种传递遗传信息的方式都有优点。,Inasexualreproductiontheparentorganismgivesrisetooffspringthataregeneticclonesoftheparent.,无性生殖产生后代时克隆（完全复制）了中亲本的遗传信息。,Theadvantagesofthistypeofreproductionarethatitpreservestheparentssuccessfulgeneticcomplement,requireslittleornospecializationofreproductiveorgans,andismorerapidthansexualreproduction.,这种生殖类型的优点是它保存了亲本成功的遗传信息，基本或完全不需要特化出生殖器官，与有性生殖相比更迅速。,Amajordisadvantageoftheasexualmodeisthatasinglecatastrophiceventordiseasemaydestroyanentirepopulationofgeneticallyidenticalorganisms.,无性类型的主要缺点是单一的灾难性事件或疾病就可以摧毁遗传信息完全相同的整个种群。,Aprimebenefitofsexualreproductionisthatitprovidesgeneticvariabilityandareadymechanismfortheeliminationofdeleteriousmutations.Italsoallows“new”geneformstoariseandspreadthroughpopulations.,有性生殖的主要好处是它能够提供遗传的多样性，具有迅速的清除有害变异的机制。它也使新基因形式出现、增加并扩展到整个种群。,Reviewtheformercontent：,1.anaphasen.分裂后期2.Cellplaten.细胞板3.centromeren.着丝粒;着丝点4.chalonen.抑素5.chromatidn.染色单体6.chromatinn.染色质7.cytokinesisn.胞质分裂8.diploidn.二倍体9.haploidn.单倍体10.histonen.组蛋白11.Homologouspairn.同源染色体对,12.interphasen.分裂间期13.karyotypen.核型，染色体组型14.meiosisn.减数分裂15.Metaphasen.中期16.metaphaseplaten.中期板，赤道板17.mitosisn.有丝分裂18.nucleosomen.生化核小体19.prophasen.前期20.spindlen.纺锤体21.telophasen.末期,Exercises,IKeyterms:matching,Matcheachtermontheleftwiththemostappropriatedescriptionontheright,a.DNA+histoneb.twosetsc.XandYd.onesete.chromosomedisplayf.setofmicrotublesg.plantdivisionh.gameteproductioni.sequenceofcellgrowthanddivisionj.celldivisionk.crossingoverl.inhibitcelldivisionm.Divisionofcytoplasmn.singlechromosomecopyo.positivelychargedprotein,1.cytokinesis2.synapsis3.histone4.mitosis5.cellcycle6.chalone7.spindle8.chromatid9.nucleosome10.diploid11.meiosis12.cellplate13.sexchromosome14.karyotype15.haploid,IKeyterms:matching,II.Trueorfalse,AutosomesincludeXandYchromosomes.2.CellsenterG2attheendoftheSphase.3.Chalonespromotecelldivision.4.Thenuclearenvelopeformsintelophase.5.Plantcellshavethemostprominentcentrioles.6.Nucleardivisionmayoccurwithoutcytokinesis.7.Homologouschromosomespairinsynapsis.8.Chromosomesbreakatchiasmata(交叉).9.Sexualorganismscannotbecloned.10.Alldaughtercellsarehapoid.,kazmt,IIICompletion,Ifhumanchromsomesarestainedonaslide,theresultingdisplay,whichiscalledakaryotype,shouldcontaintwenty-twopairsofautosomesandonepairofsexchromosomes.TheSinSphasestandsforsynthesisbecauseduringthistimeDNAisreplicatedandhistonesaresynthesized.3.Insteadofcentrioles,mostplantsandfungihaveregionscalledmicrotubuleorganizingcenters.Duringmeiosisbutnotduringmitosis,homologouschromosomespairupinaprocessofsynapsis.Mitosisproduces2progenycells,eachwithasetofdiploidchromosomes.,IIICompletion,6.Meiosisproduces4daughtercells,eachwithahaploidsetofhaploidchromosomes.7.Microtubulescalledcentromericfibersattachtothechromosomesatthekinetochores8.Twochromatidsattachtoeachotheratthecentromere.,IVMultiplechoice,1.DNAisreplicateduringthe_.A.SphaseB.MphaseC.G2phaseD.G1phaseE.noneoftheabove,2.Membersofachromosomepaircollectivelymakeup_.A.atetrad（四分染色体）B.chromatinC.ahomologouspairD.achromatidE.anucleosome,tetrd,3.Autosomesrepresent_.A.allchromosomesfoundinanormalhumancellB.thosechromosomesfoundineggorspermcellsC.allchromosomesotherthanthesexchromosomesD.chromosomespairswithunlikemembersE.allhomologouschromosomes,4.Inatypicalvertebratethelongestphaseis_.A.SB.MC.G2D.G1E.Noneoftheabove,vtbrt脊椎动物,5.Anormaldiploidhumancellcontains_.A.46chromosomesB.23chromosomesC.46homologouspairofchromosomesD.20chromosomesE.20pairsofchromosomesand2sexchromosomes,6.Malesexchromosomescanneverbe_.A.haploidB.homlogousC.diploidD.analogousE.duplicated,7DuringG1,S,andG2phases,acellissaidtobein_.A.theprocessofmitosisB.theprocessofmeiosisC.metaphaseD.cytokinesisE.interphase,8.Itispossiblefor2metersofDNAtofitintoahumancell5micrometersindiameterbecause_.A.DNAisbrokenintosmallfragmentsB.DNAiswoundaroundhistonesC.DNAiswoundaroundnonhistoneproteinsD.ChromosomesarecomposedofchromatidsE.Chromosomesarejoinedatthecentromere,9.TheassociationofaDNAmolecule,histonesandnonhistoneproteinsisknownasa_.A.nucleosomeB.chromosomeC.chromatinD.chromatidE.karyotype,10.Thetwodauth