生物專業(yè)英語分析解析第1頁/共96頁CellCycleThecellcycle,orcell-divisioncycle,istheseriesofeventsthattakeplaceinacellleadingtoitsdivisionandduplication(replication).Incellswithoutanucleus(prokaryotic),thecellcycleoccursviaaprocesstermed

binaryfission.第2頁/共96頁Incellswithanucleus(eukaryotes),thecellcyclecanbedividedintwoperiods:Interphase—duringwhichthecellgrows,accumulatingnutrientsneededformitosisandduplicatingitsDNA.第3頁/共96頁Themitosis(M)phase,duringwhichthecellsplitsitselfintotwodistinctcells,oftencalled"daughtercells"andthefinalphase,cytokinesis,wherethenewcelliscompletelydivided.Thecell-divisioncycleisavitalprocessbywhichasingle-celledfertilizedeggdevelopsintoamatureorganism,aswellastheprocessbywhichhair,skin,bloodcells,andsomeinternalorgansarerenewed.第4頁/共96頁第5頁/共96頁第6頁/共96頁Beforeacellcanentercelldivision,itneedstotakeinnutrients.Allofthepreparationsaredoneduringtheinterphase.Interphaseproceedsinthreestages,G1,S,andG2.Celldivisionoperatesinacycle.Therefore,interphaseisprecededbythepreviouscycleofmitosisandcytokinesis.Interphaseisalsoknownaspreparatoryphase,inthisstagenucleusandcytosoldivisiondoesnotoccur.Thecellpreparestodivide.Interphase第7頁/共96頁G1PhaseThefirstphasewithininterphase,fromtheendofthepreviousMphaseuntilthebeginningofDNAsynthesisiscalledG1(Gindicatinggap).Itisalsocalledthegrowthphase.Duringthisphasethebiosyntheticactivitiesofthecell,whichhadbeenconsiderablysloweddownduringMphase,resumeatahighrate.第8頁/共96頁Thisphaseismarkedbytheuseof20aminoacidstoformmillionsofproteinsandlateronenzymesthatarerequiredinSphase,mainlythoseneededforDNAreplication.DurationofG1ishighlyvariable,evenamongdifferentcellsofthesamespecies.Itisunderthecontrolofthep53gene.第9頁/共96頁SPhaseTheensuingSphasestartswhenDNAsynthesiscommences;whenitiscomplete,allofthechromosomeshavebeenreplicated,i.e.,eachchromosomehastwo(sister)

chromatids.Thus,duringthisphase,theamountofDNAinthecellhaseffectivelydoubled,thoughtheploidyofthecellremainsthesame.第10頁/共96頁Duringthisphase,synthesisiscompletedasquicklyaspossibleduetotheexposedbasepairsbeingsensitivetoexternalfactorssuchasanydrugstakenoranymutagens(suchasnicotine).第11頁/共96頁G2PhaseThecellthenenterstheG2phase,whichlastsuntilthecellentersmitosis.Again,significantbiosynthesisoccursduringthisphase,mainlyinvolvingtheproductionofmicrotubules,whicharerequiredduringtheprocessofmitosis.InhibitionofproteinsynthesisduringG2phasepreventsthecellfromundergoingmitosis.第12頁/共96頁第13頁/共96頁MitosisMitosisistheprocessbywhichaeukaryoticcellseparatesthechromosomesinitscellnucleusintotwoidenticalsetsintwonuclei.Itisgenerallyfollowedimmediatelybycytokinesis,whichdividesthenuclei,cytoplasm,organellesandcellmembraneintotwocellscontainingroughlyequalsharesofthesecellularcomponents.第14頁/共96頁Mitosisandcytokinesistogetherdefinethemitotic(M)phaseofthecellcycle-thedivisionofthemothercellintotwodaughtercells,geneticallyidenticaltoeachotherandtotheirparentcell.Thisaccountsforapproximately10%ofthecellcycle.第15頁/共96頁第16頁/共96頁Mitosisoccursexclusivelyineukaryoticcells,butoccursindifferentwaysindifferentspecies.Forexample,animalsundergoan"open"mitosis,wherethenuclearenvelopebreaksdownbeforethechromosomesseparate,whilefungisuchasAspergillusnidulansandSaccharomycescerevisiae(yeast)undergoa"closed"mitosis,wherechromosomesdividewithinanintactcellnucleus.Prokaryoticcells,whichlackanucleus,dividebyaprocesscalledbinaryfission.第17頁/共96頁MeiosisMeiosisisaspecialtypeofcelldivisionnecessaryforsexualreproductionineukaryotes.Thecellsproducedbymeiosisaregametesorspores.Inmanyorganisms,includingallanimalsandlandplants(butnotsomeothergroupssuchasfungi),gametesarecalledspermandeggcells.第18頁/共96頁第19頁/共96頁第20頁/共96頁Whilsttheprocessofmeiosisbearsanumberofsimilaritieswiththe'life-cycle'celldivisionprocessofmitosis,itdiffersintwoimportantrespects:Theoutcomeofmeiosisisfour(geneticallyunique)haploidcells,comparedwiththetwo(geneticallyidentical)diploidcellsproducedfrommitosis

第21頁/共96頁Thechromosomesinmeiosisundergoarecombinationwhichshufflesthegenesproducingadifferentgeneticcombinationineachgamete,comparedwiththeco-existenceofeachofthetwoseparatepairsofeachchromosome(onereceivedfromeachparent)ineachcellwhichresultsfrommitosis第22頁/共96頁Glossary

Anaphase

后期;分裂后期Cellplate

窩眼盤;細(xì)胞板Centromere[‘sentr?,mi?]

n.[生]著絲點(diǎn),著絲粒Chalone[‘k?l?un]n.[生化]抑素Chromatid[‘kr?um?tid]n.染色分體Chromatin[‘kr?um?tin]n.核染質(zhì),染色質(zhì)第23頁/共96頁第24頁/共96頁第25頁/共96頁第26頁/共96頁Astraladj.星形的；星際的

第27頁/共96頁第28頁/共96頁P(yáng)hycoplastn.藻質(zhì)體;phragmoplastn.成膜體;coalescevi.聯(lián)合，合并;perforatevt.穿孔于，在…上打眼;plasmodesmata(復(fù))胞間連絲第29頁/共96頁第30頁/共96頁第31頁/共96頁第32頁/共96頁Lamellan.薄層；薄片；瓣；鰓第33頁/共96頁第34頁/共96頁第35頁/共96頁第36頁/共96頁第37頁/共96頁Terminologyn.專門名詞；術(shù)語，術(shù)語學(xué)；用辭第38頁/共96頁第39頁/共96頁第40頁/共96頁Cytokinesis[,sait?ukai‘ni:sis]

n.細(xì)胞漿移動,原漿移動;胞質(zhì)分裂Diploid[‘dipl?id]a.雙重的,雙倍性的,倍數(shù)的

n.倍數(shù)染色體Haploid[‘h?pl?id]

n.[生物]單倍體,僅有一組染色體的細(xì)a.單一的Histone[‘hist?un]n.[生化]組蛋白homologouspair

同源染色體對第41頁/共96頁CytokinesisCytokinesis,fromthegreekcyto-(cell)andkinesis(motion,movement),istheprocessinwhichthecytoplasmofasingleeukaryoticcellisdividedtoformtwodaughtercells.Itusuallyinitiatesduringthelatestagesofmitosis,andsometimesmeiosis,splittingamitoticcellintwo,toensurethatchromosomenumberismaintainedfromonegenerationtothenext.

第42頁/共96頁第43頁/共96頁第44頁/共96頁第45頁/共96頁第46頁/共96頁第47頁/共96頁第48頁/共96頁第49頁/共96頁第50頁/共96頁第51頁/共96頁第52頁/共96頁第53頁/共96頁Interphase[‘int?(:)feiz]n.中間相(界面,相間的)；a.相間的Karyotype[‘k?ri?taip]

n.[生物]染色體組型；核型Meiosis[mai‘?usis]n.減少；減數(shù)分裂Metaphase[‘met?feiz]a.中期,轉(zhuǎn)位期metaphaseplate

赤道板；中期板第54頁/共96頁KaryotypeAkaryotype(Greekkaryon=kernel,seedornucleus)isthenumberandappearanceofchromosomesinthenucleusofaeukaryotic

cell.Thetermisalsousedforthecompletesetofchromosomesinaspecies,oranindividualorganism.第55頁/共96頁Karyotypesdescribethenumberofchromosomes,andwhattheylooklikeunderalightmicroscope.Attentionispaidtotheirlength,thepositionofthecentromeres,bandingpattern,anydifferencesbetweenthesexchromosomes,andanyotherphysicalcharacteristics.Thepreparationandstudyofkaryotypesispartofcytogenetics.第56頁/共96頁第57頁/共96頁第58頁/共96頁第59頁/共96頁第60頁/共96頁第61頁/共96頁第62頁/共96頁Mitosis

[mi‘t?usis]n.有絲分裂,間接核分裂Nucleosome[‘nju:kli?s?um]n.[生化]核小體Prophase[‘pr?ufeiz]n.（分裂）前期Spindle[‘spindl]n.紗錠,紡錘,軸；v.變細(xì)長Telophase[‘tel?feiz]n.（分裂）末期Repository[ri‘p?zit?ri]n.貯藏室(博物館,資源豐富地區(qū))第63頁/共96頁Coil[k?il]

n.卷,騷動；v.盤繞,卷；n.【電】線圈,繞組Cluster[‘kl?st?]

n.串,叢,群；v.聚合,成串,叢生,使...聚集Pictorial

[pik‘t?:ri?l]a.繪畫的;n.畫報Immortal[i‘m?:tl]a.不朽的;n.不朽的人物Metabolism[me‘t?b?liz?m]n.新陳代謝Condense[k?n‘dens]v.濃縮,摘要,縮短第64頁/共96頁Replicate[‘replikit]v.折疊,復(fù)制,模寫;n.八音階間隔的反復(fù)高低音Kinetochore[ki‘ni:t?k?:]n.[生]動粒,著絲粒,著絲點(diǎn)Centriole[‘sentri?ul]n.[生]細(xì)胞中心粒,中心體Pinch[pint?]

n.捏,撮,困苦;v.掐,使...困苦,節(jié)儉第65頁/共96頁第66頁/共96頁第67頁/共96頁第68頁/共96頁第69頁/共96頁第70頁/共96頁P(yáng)rogeny['pr?d?ini]n.子孫(結(jié)果,次級粒子)Synapsis[si‘n?psis][生]染色體結(jié)合,聯(lián)會Align[?‘lain]v.排列,調(diào)整,定中心,校直,使結(jié)盟,使成一行Catastrophic[,k?t?‘str?fik]a.悲慘的,災(zāi)難的Deleterious[,deli‘ti?ri?s]a.有害于,有毒的Gamete[‘g?mi:t]

n.配偶子Tetrad['tetr?d]

四位組第71頁/共96頁SynapsisSynapsis(alsocalledsyndesis)isthepairingoftwohomologouschromosomesthatoccursduringmeiosis.Itallowsmatching-upofhomologouspairspriortotheirsegregation,andpossiblechromosomalcrossoverbetweenthem.第72頁/共96頁SynapsistakesplaceduringprophaseI.Whenhomologouschromosomessynapse,theirendsarefirstattachedtothenuclearenvelope.Theseend-membranecomplexesthenmigrate,assistedbytheextranuclearcytoskeleton,untilmatchingendshavebeenpaired.第73頁/共96頁Thentheinterveningregionsofthechromosomearebroughttogether,andmaybeconnectedbyaprotein-RNAcomplexcalledthesynaptonemalcomplex.Whileautosomesundergosynapsisduringmeiosis,sexchromosomesoftenremainunpaired.第74頁/共96頁第75頁/共96頁第76頁/共96頁第77頁/共96頁第78頁/共96頁第79頁/共96頁Text

Withinthenucleusarethechromosomes-tightlycoiledstrandsofDNAandclustersofassociatedproteins.EachlongstrandofDNAcombineswithhistonesandnonhistonetomakeupthesubstancechromatin.第80頁/共96頁第81頁/共96頁第82頁/共96頁第83頁/共96頁SUMOproteinsaresimilartoubiquitin,andSUMOylationisdirectedbyanenzymaticcascadeanalogoustothatinvolvedinubiquitination第84頁/共96頁第85頁/共96頁第86頁/共96頁Karyotypesrevealsthatinmostcellsallbutsexchromosomesarepresentastwocopies,referredtoashomologouspairs.Organismswhosecellscontaintwosetsofparentalchromosomesarecalleddiploid;thosewithcellscontainingasinglesetofparentalchromosomesarecalledhaploid.第87頁/共96頁Manycellsinmulticellularorganisms,includinganimalmuscleandnervecells,eitherslowthecycleorbreakoutofitaltogether.ThefourthphaseofthecellcycleisMphase,theperiodofmitosis,duringwhichthereplicatedchromosomescondensedandmovean