生物专业英语第三版蒋悟生编--课文翻译

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Inside tｈe ＬivｉnｇCｅll: Sｔrucｔurｅanｄ

Funｃtioｎof Ｉnternal Cell PartｓCytoplasm: The Ｄynamic, MobiｌｅＦactory

细胞质：动力工厂

Most of the propeｒｔｉeｓｗe assｏciatｅwitｈlｉｆe arｅｐroｐertｉｅs of the cytoplasm．Mｕch of tｈe ｍass of a cell ｃonsistｓof tｈis sｅｍifluid substａｎce, ｗhicｈiｓbouｎｄed ｏn thｅouｔｓide bｙthe ｐlasmａmeｍbrane.Ｏrganeｌｌes are suｓpended witｈin ｉt，supportｅd by the ｆilaｍｅntous netwoｒk ofｔhe cｙtoskelｅtoｎ. Ｄｉssoｌvｅｄｉn tｈeｃyt ｏplａsｍic fluiｄare nuｔrieｎts，iｏns,soluｂleｐｒoｔeins, an ｄｏthｅｒｍatｅｒiａｌs ｎｅｅded for ｃell functioninｇ．

生命的大部分特征表现在细胞质的特征上。细胞质大部分由半流体物质组成，并由细胞膜(原生质膜)包被。细胞器悬浮在其中,并由丝状的细胞骨架支撑。细胞质中溶解了大量的营养物质，离子,可溶蛋白以及维持细胞生理需求的其它物质。

The Ｎuclｅuｓ：Iｎｆｏrmatiｏn Central(细胞核：信息中心)

Thｅeukａryotic ceｌl nucｌｅus iｓtｈｅlarｇｅst orｇanelle aｎdｈｏuseｓthe ｇeneｔiｃmaterial (DNA) oｎchromoｓomes.（In pｒoｋaｒyoｔes the ｈerｅditaｒｙｍａterial iｓfound in ｔｈe ｎuｃleoiｄ.）Thｅnuclｅｕｓａlｓo cｏntains o ｎe or two orｇａneｌｌes-thｅnｕcｌeoli-thａｔpｌay ａrole in c ｅｌｌdiｖisiｏn．A pore－perｆoｒaｔed sａc callｅd theｎuclear envｅlope sｅparates the ｎuｃleus and itsｃontentｓf ｒom ｔhe cytoｐlasｍ．Ｓｍａll molecuｌeｓcan ｐasｓtｈｒo ｕｇh the nucｌｅar enveloｐe，ｂut lａrgerｍolｅｃuｌｅs ｓuch as mRNＡand riboｓｏｍes mｕst eｎter ａnd exit ｖia tｈe pores. 真核细胞的细胞核是最大的细胞器,细胞核对染色体组有保护作用（原核细胞的遗传物质存在于拟核中)。细胞核含有一或二个核仁,核仁促进细胞分裂。核膜贯穿许多小孔,小分子可以自由通过核膜，而象mRNA 和核糖体等大分子必须通过核孔运输。

Orgaｎeｌlｅs：Spｅcｉalized Ｗoｒk Uｎits（细胞器:特殊的功能单位)

All eukａryoｔic ceｌｌs containｍｏst of tｈe ｖarious kｉnds of orｇaneｌleｓ, andｅaｃh oｒgａnelle peｒforｍs a spｅｃiaｌ

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ｉｚed functiｏn in the cell. Organeｌlesｄescribed ｉn thiｓsecti ｏｎiｎｃlｕdｅriｂosomｅs, ｔｈe eｎdoplasmic rｅｔiculum，the Ｇｏlgi cｏmplｅx,vａcｕoleｓ, lysosomｅs, miｔocｈondriａ, ａｎd the ｐlastiｄｓof plａｎt ｃｅlls.

所有的真核细胞都含有多种细胞器,每个细胞器都有其特定功能。本节主要介绍核糖体，内质网，高尔基体系，液泡，溶酶体,线粒体和植物细胞中的质体。

The nuｍber of ribosomes witｈｉn a ceｌl ｍay range fｒom ａfｅw huｎdrｅd to manｙthｏusaｎdｓ. Thｉs ｑuanｔiｔy refｌｅct ｓthe fａct tｈａt,riｂoｓomes are the siteｓat which amiｎo acｉdｓare aｓｓeｍｂled ｉnｔo ｐｒoteinｓfor export or fｏr uｓe ｉn cｅll pｒocessｅs． A ｃｏmplete ribosoｍe is compｏsｅd ｏf one larger anｄone ｓmaller suｂunit. Durｉｎg protein syｎthesｉs ｔhe two subunｉｔs move ａlong a strand of ｍRNＡ，"reａdiｎｇ＂the genetic sequence codeｄin ｉt and traｎsｌａting thａt seｑｕence inｔo ｐrotein. Sｅvｅral riｂoｓomeｓmaｙbｅｃome atｔacheｄｔoａsingｌe mRNＡstrand;such a combｉnatioｎis ｃａｌlｅd a polysｏme. Moｓt cｅllulaｒproteins aｒe mａnufactuｒｅd on ribｏｓｏmeｓｉn the cytｏplａｓm.Ｅｘportabｌe protｅｉns aｎd memｂrａnｅproｔｅins are usｕallｙmade iｎaｓｓoｃiatｉon with tｈｅenｄｏｐｌａsｍｉc reticｕlum.

核糖体的数量变化从几百到几千,核糖体是氨基酸组装成蛋白质的重要场所。完整的核糖体由大亚基和小亚基组成。核糖体沿着mRNA 移动并阅读遗传密码，翻译成蛋白质。一条mＲNA上可能有多个核糖体,称多聚核糖体。大多数细胞蛋白是由细胞质中核糖体生产。输出蛋白和膜蛋白通常与内质网有关。

The enｄｏplasmic rｅtiｃuluｍ, a lａcyａrray of membraｎous sacs, tubｕｌeｓ,and vｅsicｌes, ｍayｂe eitｈｅr rouｇh(REＲ) or smooth (SＥR)．Both typeｓplay rｏles in the sｙｎｔheｓiｓandｔraｎsｐoｒt of proteins.The RER, ｗｈｉch iｓstudｄed witｈpolyｓoｍeｓ,alｓo seems to be tｈe souｒｃe of tｈｅnuclear envｅloｐe ａftｅr a cｅｌl pｉdｅｓ.

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内质网，带有花边的生物囊,有管状,泡状之分，以及光滑和粗糙面区别。两种都与蛋白质的合成和运输有关。粗糙内质网上分布许多核糖体,也可能提供细胞分裂后所需的细胞膜。

SＥR lackｓpolysomes; it is ａcｔivｅinｔhe syｎthｅsｉs o ｆfatｓａnd steｒoids anｄin ｔhｅoxidation of toxicｓｕb ｓtaｎces in thｅcell.Both typｅs ｏf endopｌasmic reｔiculuｍserve as coｍｐａrtments wｉｔhin ｔhe cell wherｅspeｃifiｃpｒoducts can be ｉsoｌａted and subｓequentｌy ｓｈunted tｏparticular areaｓｉn or outsiｄｅthe ceｌｌ.

光滑内质网上无核糖体，主要作用是脂肪和类固醇的合成以及细胞内有毒物质的氧化。两种内质网合成的产物在其中进行分流或运输到细胞外。

Tranｓｐoｒｔｖesｉcles ｍaｙｃａｒｒy exporｔable ｍoｌe ｃuｌesｆroｍthe endｏｐlaｓmic ｒeticulum toａｎotｈer membranｏｕsｏrganellｅ, thｅGolgi complex．Witｈｉｎth ｅGolgi comｐlex mｏlecules are modifiｅd aｎｄpaｃkａgｅd ｆｏr ｅxporｔout oｆthe cell ｏr fｏr delｉvery else ｗｈｅrｅin ｔhｅcytｏpｌasｍ.

运输小泡能够将可运输分子从内质网运输到高尔基复合体上。在高尔基复合体中修饰,包装后输出细胞或传递到细胞质中的其他场所。

Ｖacuolｅsｉn ｃｅllsａpｐearｔｏbe hｏｌlow sacs but are aｃtuａlly filled wｉth ｆｌｕid anｄｓoluble mｏｌecｕlｅs. T ｈe ｍoｓｔprominenｔvaｃｕｏｌeｓappeaｒｉn pｌａnｔce ｌｌs ａｎd serｖe as ｗａter ｒeservｏirs aｎｄstｏragｅsiｔｅｓｆor sugars aｎd otｈｅr moｌeculｅs. Ｖaｃuｏｌeｓｉn anima ｌｃeｌls carry out phaｇｏcyｔoｓis (ｔhe intakｅof particulat ｅmatter) aｎｄpiｎｏcytosiｓ（vａcuolａr driｎkinｇ).

细胞中的液泡好象是中空的,但实际上充满了液体和可溶分子。最典型的液泡存在于植物细胞中，储备水,糖以及其它分子。动物中的液泡起吞噬和胞饮作用。

Aｓｕｂset ｏｆvａcuolｅｓare the orgａnelｌes ｋｎｏｗｎaｓlysosｏmes, which contain digestivｅｅnzyｍes (paｃkaged in lｙsosｏmes ｉn thｅGolgi ｃomplｅx) that ｃan breakｄｏｗn most biｏlogｉcal macrｏmｏleｃｕles. Ｔhey ａct tｏdigeｓｔfood particles andｔｏdegrａde damaｇed cｅlｌpａrts.

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溶酶体是液泡亚单位，含有消化酶，降解大部分生物大分子。消化食物微粒和降解损伤的细胞残片。

Miｔｏcｈondｒia aｒe the ｓites ｏｆenerｇy-yiｅldiｎg chemical reａｃtｉons in aｌl ceｌｌs．In ａｄdｉtion, pｌant ceｌlｓｃoｎｔain pｌaｓｔids that utiliｚｅｌｉgｈt eｎergy ｔo manufacture caｒｂohydraｔes in thｅprｏｃess ｏｆphｏtosyntｈｅsis. It is ｏn the large sｕｒfａce area provided by the i ｎnｅｒcriｓtａe oｆmitochoｎdriａthat AＴP-generatｉnｇenｚymes are ｌoｃａteｄ. Mｉtochonｄｒiａare ｓｅlf-ｒｅｐlicatｉn ｇ, andｐrｏbably tｈｅｙａre thｅeｖｏｌｕtiｏnaｒy deｓcｅｎｄaｎtｓof what wｅrｅonceｆｒee-ｌｉvinｇprokａryotes.

线粒体是细胞中化学产能的场所。另外，植物细胞中的质体在光合作用中利用光能产生碳水化合物,线粒体内嵴上提供了很大的表面积并分布着产AＴP酶。线粒体自我复制，并且可能是自由生活的原核生物在进化中形成的后代。

Therｅａre two typeｓoｆplａstｉdｓ：ｌeuｃoplasts, ｗｈｉcｈlacｋpigmｅnts and serve ａｓｓｔｏrａge sｉtｅs for ｓtarch, proteiｎs，aｎd ｏilｓ; ａnd chrｏmｏplasts, whｉch co ｎtａｉｎpｉgｍenｔs. Thｅmost importantｃhｒoｍoplａsｔs a ｒe cｈlｏropｌaｓtｓ-oｒｇaneｌles tｈａt cｏｎｔain tｈe ｃhlorophｙｌl usｅd in photｏｓynｔｈeｓｉs.Ｔhe intｅrnal strucｔure of cｈloropｌａsｔsｉncluｄeｓｓtacks of membrａnes ｃalled grａnａ, ｗhicｈarｅembedｄed in a ｍatｒｉx cａllｅｄthｅstｒoma．

质体有两种类型：白色体，缺乏色素，是淀粉,蛋白质和油的储备场所;色质体,含有色素。叶绿体是最重要的色质体,含有与光合作用有关的叶绿素。叶绿体的内部结构是由多层膜形成的叶绿体基粒，其中包埋在基质中的基粒称子座。

The Cytｏskｅletｏn（细胞骨架)

Alｌeukaryotic cellｓhave a ｃytosｋeleton, whicｈisａconvoluted latｔicewoｒk ｏf filameｎtｓand tubuｌｅs ｔhaｔappeaｒs to filｌaｌl ａｖａｉlable spaｃe iｎthe cell and p ｒovｉdes suppｏrt ｆor vａrious other ｏｒganｅlleｓ. A ｌarｇe ｐortiｏn of the cｙｔosｋｅleｔon ｃoｎsｉsｔｓof threadlikeｍicroｆilamentｓcｏｍposeｄmaiｎlyｏf tｈｅcｏｎｔrａctile

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proｔeｉn ａcｔｉｎ．Theyａre inｖolｖｅd in many types of ｉntｒacelｌulaｒmovｅｍenｔs in ｐlaｎt and aｎimal cｅｌls. Ａsecond ｐrotein，ｍyosin, is iｎvolveｉn the conｔracｔioｎof mｕsｃｌeｃells．Anoｔｈeｒmain struｃtuｒal cｏmponent oｆthｅcytｏskelｅton ｃonｓists of mｉｃrotubｕlｅｓ，wｈｉｃｈare composeｄoｆtheｇlｏbuｌar proteiｎtubuｌin and toget ｈer act as scaffolｄｉng that ｐrｏvｉｄes ａstabｌe cell shapｅ. Cytoskeletal iｎtermeｄiate fｉlamentｓaｐpear to impaｒt tｅnsile ｓtrength to the celｌcｙtｏｐlaｓm. Mechanoｅｎｚymes such as mｙosin, dynein,ａｎd kinｅsin inteｒact ｗｉth the cyｔosｋeletaｌfilaｍenｔs and tubulｅs to geｎeraｔe ｆorceｓthａt cause movｅmｅnts.

所有的细胞都有细胞骨架，网络结构的纤丝充满了它所能触及的全部空间并且对细胞器提供支持作用。细胞骨架大部分由微丝组成,微丝主要由可收缩的肌动蛋白组成。动植物细胞的许多种类型细胞内运动与肌动蛋白有关。第二类蛋白是肌球蛋白,它与肌肉细胞的收缩有关。细胞骨架的另一个主要结构成分是微管，由球状的微管蛋白组成,象脚手架一般维持细胞的稳定形态。细胞骨架的中间丝提供了细胞质伸缩动力。机械酶,例如,肌球蛋白,动力蛋白，驱动蛋白与微丝，微管相互作用产生动力而引起细胞运动。

Cellular Ｍovemｅnts(细胞运动

Althoｕgｈｔhｅcytosｋeleｔon pｒovidesｓome stability稳固to cells, iｔs microｔubｕlｅs

英［?ｍａikｒ?ｕ?ｔjｕ:bju：l]aｎd ｆiｌamentｓ丝状物aｎd t ｈeir aｓsoｃiateｄproteｉns enablｅcｅlｌｓto moｖｅｂy creepinｇ爬行ｏｒgliｄing 滑动.Such ｍｏvements reｑuire a solid固体的ｓubstraｔe tｏwｈich ｔhe cell cａn adｈere附着ａnd ｃaｎbe ｇuidｅd by the geｏmｅtｒyｄ?ｉ??miｔri］几何形状of thｅsｕrface. Sｏme cellｓaｌsoｅｘｈｉbiｔ[ｉɡ?zｉbit]展览chemoｔaxis, kem??ｔ?ｋｓis趋药性the ａbiｌity ｔo move toｗard or away fromｔｈe sourｃｅof a ｄｉffusinｇ扩散

ｃheｍｉcaｌ．

尽管细胞骨架提供了细胞的某些稳定性，微丝,微管及相关蛋白能使细胞爬行或滑动。这种运动需要固体基质依托并通过表面几何形状的改变而运动。某些细胞具备趋药性,即趋向或逃离扩散开的化学源。

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Certaiｎeuｋaryｏtiｃｃellｓcａn swiｍfreeｌyｉｎliqｕid

ｅnｖiｒonmenｔs，ｐｒopelled ｂｙwhｉpｌiｋe ｃiｌｉａ

［?sili?]纤毛oｒｆlagella英[fｌ??d?el?鞭毛. Bothｃiｌｉa anｄfｌageｌla hａve the sａmｅinterｎaｌｓtrｕcture: nｉne ｄoｕbｌｅｔs（ｐａｉrsｏｆmicrotｕｂules) arｅarrangｅｄin a ｒｉng and exteｎd thｅlｅｎgth oｆthe cｉliｕm or flaｇelluｍ，and tｗo ｍｏｒe ｍｉｃrotuｂｕlｅｓrun ｄown tｈe ceｎter of th ｅｒinｇ．Every ciliｕm oｒfｌａｇelluｍgrｏws only from thｅcell surfacｅwheｒｅ a baｓal body基体ｉｓｌocaｔｅd．Movｅmｅnｔis bａsed oｎthe acｔｉvｉtiｅs ｏf tiｎy dyn ｅin动力蛋白side arms tｈat ｅｘtｅndｆrom ｏne of tｈｅm ｉcｒotubules of eacｈdｏｕblet成对的东西．

某些真核细胞能在液体液体中自由运动，由纤毛或鞭毛推动。纤毛和鞭毛具有同样的内部结构:九个双微管环形排列，纵向延伸，环中心是两个或以上微管组成。纤毛或鞭毛从细胞表面的基体出生长,双微管的动力蛋白臂从一侧延伸到另一侧而引起运动。

?Nuｔrients，proteinｓ, and ｏther materｉａls withiｎｍost pｌant c ｅｌls ａre ｍoveｄabｏut vｉa cｙtoplasmic streaming. Tｈｅpｒoｃess occｕrs ａs myosin ?mａi?usin肌凝蛋白proｔeins attａched to orgaｎｅllｅs 细胞器,小器官puｓh againｓt micrｏfｉlamｅｎts arrａyed ［??rei］展示tｈｒoughoｕt ｔhe cｅll. Ｍicｒofｉlａments anｄmicrotubuｌes are ｒesponsiｂle fｏr alｍost ａllｍajor cｙtopｌasmic movements.Dｕrｉｎｇｃeｌl pｉsioｎ, ｍicｒotｕbules oｆthe spiｎｄle asｓembｌed集合, 收集from tubutiｎs ｕbuｎｉｔs ｎeａr oｒganelleｓcaｌlｅｄcｅntrｉoles moveｔhe cｈｒomｏsomes.

大部分植物细胞的营养,蛋白质和其它物质由细胞质流运输。这个过程是由于依附在细胞器上的肌球蛋白反推排列在细胞周围的微丝形成的。绝大部分细胞质运动由微丝和微管完成。在细胞分裂期间,中心粒周围的由微管蛋白亚基装配形成的纺锤体微管移向染色体。

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Ｇlossarｙ

cytopｌａｓm (细）胞质

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The liｖing conｔents oｆa cｅｌｌbouｎｄed exteｒnally ｂy the plasmaｌｅmma，inｃludingａn aqｕｅｏuｓgrouｎｄｓubｓｔａｎｃe (ｈyaｌｏｐlasｍ, ceｌl sａp, or cｅll maｔｒix) cｏntaining orgａnelles and variousｉnclusｉons but excluding tｈe nucleus and viｓibｌe vacuｏles.

cytoskeｌeｔon 细胞骨架

Of eukａrｙotｉｃｃellｓ,ａn internaｌ"skeleton＂．Its mic ｒｏtuｂuｌes aｎd ｏther componentｓｓtｒuｃｔｕｒally suｐｐoｒt thｅcｅll,orｇanｉzｅanｄmoveｉtｓｉｎtｅｆtiａl componenｔs. Tｈe cytｏsｋeｌetｏn aｌso helps free－liviｎｇcelｌs moｖｅthroｕgｈｔhｅir ｅnvirｏnmeｎt．

nucleｕs 细胞核，核(复数nuclei)

Ｔhe ｏrｇａnｅlle of tｈｅeukaryote ｃellｔｈat coｎｔaｉns

thｅchromｏsｏmes and ｈeｎcｅultimａtely controls ｃeｌlularａctivity and ｉnheｒiｔance throｕgh ｔhe ａctivｉty of tｈｅｇeｎetic maｔeｒial，DNＡ

chromosome染色体

AＤＮA－histone ｔｈreａｄrｅsiding in tｈe ｎｕcleusｏf a cell.Ｅacｈchromｏsomeｐossesses ｔwo tｅｌｏmeres and a ｃｅnｔrｏmｅｒe, aｎd some contaiｎa nucleolｕs oｒｇａｎizer. ＲNA ｐroｔｅins are iｎvariabｌｙassocｉateｄｗｉtｈthe chr ｏｍosoｍe．

nuｃleoid 拟核,类核,核质体

TｈｅDNA－cｏｎtaining ａrｅa of a prokarｙoｔe cｅｌl, anａlogous to the eukａryotｅnｕcleus ｂuｔnot ｍｅmｂraｎｅbound ｅd．

nucleoｌｉ核仁（单数ｎucleoｌuｓ)

Nｕcleaｒｓtｒuctｕres composed of complｅｔed ｏr paｒtiａlly cｏmpleｔed riｂosｏmes aｎd ｔhe ｓpecific paｒｔs of chromｏsomeｓｔｈat contain ｔhe infon-naｔｉｏn for their coｎstruｃtion. ｎuclear ｅnveｌope 核膜，核被膜

A ｄouble mｅmbrａｎe (ｔｗo ｌｉpiｄbｉｌayeｒｓanｄassoc ｉated proteins）that iｓthe ouｔermｏｓｔportiｏn of a cell nｕc ｌeｕs.

ribosoｍe 核糖体

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Smａｌｌｓtrucｔureｓcomposｅd of tｗｏproｔein ａnd ｒiｂonuｃleic ａcid subunitｓｉｎvｏlved in ｔhe assｅmbly ｏf proteins from amｉno aciｄs.

polysome 多核糖体

Oｆpｒoteiｎsynthesis,severａｌrｉbosｏmes aｌl trａnsｌaｔing ｔｈe ｓａｍe mｅsｓｅｎger ＲNA mｏlｅculｅ，onｅaｆt ｅｒｔhe other.

eｎdoｐlaｓmｉc reticulum 内质网

Fｏｌdｅd meｍbｒanｅｓａnｄtｕｂｅs ｔhrouｇhoｕt thｅeｕkaryｏtiｃｃell that prｏｖｉde ａlａrgｅsｕrfａce uｐｏn which ｃhｅｍical aｃｔivities takｅpｌace.

Golgｉｃomｐlex 高尔基复合体

A sｔａｃk oｆflatteｎeｄ, smｏoth，ｍeｍｂraｎouｓsacs; the siｔｅｏf synthesis aｎd pａｃkaｇing of cｅrtain moｌeｃｕｌes in eｕｋarｙｏtic cells．

vaｃuole液泡

Stoｒage ｃoｎtaｉｎerｗithin the ｃytoｐｌasｍｏｆａcelｌ

ｈaｖiｎg ａｓurrｏuｎding mｅmｂrane.

pｈagｏcyｔosiｓ吞噬作用

The procesｓby whicｈthｅｃelｌwｒaｐｓaroｕnｄa ｐarticle ａnd eｎｇuｌfs ｉｔ.

pinocｙtosiｓ胞饮作用

Theｐｒoｃess ｂｙｗhicｈa cｅlｌｅngｕlfs soｍｅmol ｅcules disｓｏlved ｉｎwatｅr

lysosome 溶酶体

Ａspｅｃialｉｚeｄorganelle thａｔhｏlｄs a mixture oｆhydrolytic enzyｍｅs．

mｉtｏｃhｏndｒion 线粒体(复数mitｏｃhondrｉa )A meｍbraｎouｓorganelle resembling a sｍａｌl bag wｉth a lａrｇer ba ｇresｅmbling a small bag ｗｉth a lａrger bag ｉnsidｅthat is folded baｃｋon itseｌf；servｅｓas the ｓite of ａeroｂｉc cel ｌｕlar rｅｓpiration.

plastid 质体

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Aｎoｒganelle presenｔin ａll plaｎts except bacｔｅria, ｂ

lue-green algae,andｆungi; iｔis eｎｃlｏsｅd byｔwo mｅmbr ａnｅs(the enveｌoｐｅ)and has various ｆｕnctions

chloroplａsｔ叶绿体

Ａplastid in whｉｃhｐhoｔｏsynｔhesｉｓiｓcaｒriｅd out. Chlｏroplasｔs occｕr in alｌphｏｔosynｔhetic ｏrｇanisｍｓexcept photosｙnthｅｔic bacteria blue-green algae.

stroma 基质,子座(复数ｓtromata)

Reｇioｎｗithｉn a ｃhｌoropｌast thａt ｈas no ｃｈｌoｒｏｐhｙll.

ｍicrofiｌaｍent 微丝，纤丝

Loｎg, ｆiberｌｉke structures made of prｏteｉn anｄfounｄin cells, often in ｃｌosｅaｓsociation with the microｔubules；prov ｉｄe ｓｔrｕctural sｕpｐoｒｔａｎｄenａｂle moｖemｅnt.

ａctｉn 肌动蛋白

A globulaｒcontｒactile pｒotｅin．In ｍusｃlｅcells,aｃtin i ｎtｅracts ｗith ａnothｅr proteｉn,ｍyosiｎ, to brｉnｇａbouｔcontractｉｏn.

myosin ［'maiesiｎ] 肌球蛋白

A protein ｔｈａt, ｗiｔh actiｎ,conｓｔitutes the ｐｒinciｐal elｅmeｎt oｆｔhe contｒａcｔile aｐｐaratｕｓof muscle.

miｃroｔubｕｔe 微管

Ｓmａｌl,holloｗtubes of ｐroteiｎthat fｕnｃｔion throughoｕt the ｃｙｔoplａsm to proviｄe stｒuctural sｕppｏｒt and ｅｎable ｍoveｍent．

ｔubｕｌin 微管蛋白

Ａprｏｔeｉn that ｉs ｔhｅｍａｊor cｏnstｉtueｎt oｆｍｉcrotubuleｓ.

ｄynｅin 动力蛋白，动素

Ａgrｏｕｐｏf at leａst four ｄｉstiｎct ｐroｔeｉnｓfound iｎtｈｅflagella aｎd ｍicｒoｔubules of ｅukａryotic cellｓanｄｐosseｓsing ATPase activity.

ｃhｅmoｔaxis 趋化性

A loｃomｏtoｒｙmｏvemenｔof an ｏrgaｎｉsm oｒcelｌin response tｏ, and dｉrectｅd by，an dirｅｃtｉonal stiｍulｕs.

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cｉｌia 纤毛

Numeroｕs sｈorｔ,hairｌikｅstructures prｏjectiｎｇfroｍthe cell surfaｃeｔhat ｅnable locomｏtion.

flaｇella 鞭毛(单数ｆｌagellum)

Long,haｉrlike ｓtrｕｃｔuｒｅs prｏjectｉng ｆrom the celｌｓurfaｃe thaｔｅnabｌｅｌoｃomotｉoｎ.

basal body基体

A bｏdｙidentiｃal iｎstruｃture ｔoａcｅntriole, found

alwａys aｔｔhe base of a cilｉuｍｏr euｋaryote flagelｌum.

?ｃｅnｔriole 中心粒

An oｒganｅlｌe locaｔeｄcloｓe tｏthｅnucｌeus in mosｔａｎimal anｄlｏwer plant ｃｅlls but ａｂsent fｒom proｋarｙｏtes and hiｇher plaｎts．

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Ｐhotoｓyntｈｅｓis

Ｐhｏｔosyｎtｈｅｓis oｃｃｕrsｏnｌy in the chloropｈyｌlchlo ｒopｈyll叶绿素-ｃｏntａining ｃeｌls oｆgreen plants，aｌｇae 藻，aｎd cerｔａin protisｔs 原生生物and bacteｒiａ.Ｏverall, it ｉs a ｐｒoｃesｓthat conｖeｒts ligｈt ｅnergy inｔo chｅｍｉcal eｎｅｒgy that is stored iｎthe molecuｌar bonds. Fｒoｍthe po ｉnt ｏｆvieｗoｆchｅmiｓtry ａｎd energｅtics, ｉt is the opposｉte of ceｌluｌar respｉrａtion. Whereas 然而cｅｌlular细胞的resｐｉration 呼吸iｓhiｇｈｌｙeｘerｇｏｎｉｃ吸收能量的aｎｄrｅleaseｓeｎergy, photｏsｙｎthｅsiｓ光合作用ｒｅｑuｉrｅs eｎergｙａｎｄiｓhｉghly endｅｒgoｎiｃ.

光合作用只发生在含有叶绿素的绿色植物细胞，海藻，某些原生动物和细菌之中。总体来说,这是一个将光能转化成化学能,并将能量贮存在分子键中,从化学和动能学角度来看，它是细胞呼吸作用的对立面。细胞呼吸作用是高度放能的,光合作用是需要能量并高吸能的过程。Phｏtoｓynthesis ｓtarｔs ｗiｔh ＣO２anｄH2Oａs raw materials ａｎd prｏceeｄs thrｏugh two sets of partｉal reaｃｔions. In ｔhｅfirst seｔ, ｃalled the liｇｈt-dｅpendｅnt rｅactｉｏns, ｗateｒmoleculeｓａreｓpｌｉt裂开(oxｉdｉｚｅｄ),0２is relea ｓｅd, and ATP and NＡDPＨａre formed．Thesｅreａctionｓmｕst take plaｃｅｉｎthｅpｒｅｓeｎｃe ｏf在面前ｌｉｇh ｔenergy. Ｉn ｔhe ｓecoｎｄｓet, cａｌlｅｄliｇｈt-independent rｅactions, CO2is ｒedｕceｄ(via the ａddiｔion of H aｔｏmｓ）to caｒbｏhydrate. These ｃheｍical evｅｎts ｒｅl ｙon the ｅlecｔron ｃａrriｅr NADPH ａｎd ATP generated by t ｈe ｆｉｒst sｅtｏf reactｉons.

光合作用以二氧化碳和水为原材料并经历两步化学反应。第一步，称光反应,水分子分解，氧分子释放,ATP和NＡDＰＨ形成。此反应需要光能的存在。第二步,称暗反应，二氧化碳被还原成碳水化合物,这步反应依赖电子载体NADPＨ以及第一步反应产生的ATP。

Boｔh sets of reactionｓtake plａce iｎchloｒｏｐlasｔｓ. Mosｔof the enzymes ａnd pigｍentｓ色素fｏr ｔhe lｉghtdepe ｎｄent rｅacｔions arｅeｍｂｅddeｄ深入的内含的iｎthe ｔ

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hylakoiｄ类囊体meｍbｒａｎe膜隔膜of chloroplasts 叶绿体．Tｈe darｋreactions ｔａke placeｉｎthe ｓｔｒoｍa．基质

两步反应都发生在叶绿体中。光反应需要的大部分酶和色素包埋在叶绿体的类囊体膜上。暗反应发生在基质中。

Ｈｏw Light Energy Rｅaches PｈotosynthetiｃCelｌｓ（光合细胞如何吸收光能的）

Ｔhｅeneｒgy in light phoｔons in the visｉble ｐart ｏf tｈe spe ｃtｒum can be captured ｂy bioｌｏgicaｌｍoｌecules to do co ｎsｔructiｖe work. Ｔhｅpiｇment chｌorｏphｙll in plant cｅl ｌs absorbs photｏns witｈinａｐarｔicular absoｒpｔion ｓｐeｃｔruｍｓstatement oｆｔhe amouｎt oｆlight absｏrbed by cｈloropｈｙll ａｔdifferｅｎｔwａｖｅｌｅnｇths. When ｌighｔis absorbed it ａlｔers the aｒrangement of elｅcｔrons in tｈe absorbing molecule．The aｄｄｅdｅnergy ofｔhe pｈoton bo ｏsts tｈｅeneｒgy coｎｄｉtｉon of tｈe molecule fｒom aｓtable stａtｅｔo a ｌess-stable excｉｔeｄsｔａtｅ．Durｉn ｇthe lｉｇht-depｅndent rｅactionｓoｆpｈotosｙnthesis, aｓthe aｂsorbing moleｃｕlｅretｕｒｎs to ｔhe groｕnd stａte, the "excess" ｅｘｃｉｔａtion energy iｓtｒansｍiｔted to other molｅculｅｓａnｄstoｒeｄａs chｅmical enerｇy.

生物分子能捕获可见光谱中的光能。植物细胞中叶绿素在不同光波下吸收部分吸收光谱。在吸收分子中,光的作用使分子中的电子发生重排。光子的能量激活了分子的能量状态，使其从稳定态进入不稳定的激活态。

Ａｌｌｐｈotoｓyntheｔｉｃorganisｍs contain various classｅs of chloroｐｈylls and ｏneｏr more caroｔenoiｄ(acｃessｏｒy) pigmｅｎtｓtｈａt alsｏcoｎtｒiｂutｅtｏpｈotｏｓｙntｈesis. Groups of pigmｅnt molｅcuｌes ｃalled anｔｅnnaｃomplｅxes are presenｔon thylakoids. Lｉght ｓｔｒikiｎg any oｎe ｏｆthe ｐigment mｏｌeｃuｌｅs is fuｎnｅled to ａspeciaｌｃhloｒoｐｈyllａｍolecule，tｅrmｅd aｒeactiｏｎ－cｅntｅr chloｒｏphyｌl，ｗhich dｉreｃtｌy pａｒticipatｅs iｎphotｏsyntｈｅsis. Mosｔphｏtosyｎtｈetic organisｍｓｐｏｓsess tｗｏtｙpes ｏf reactｉon-ｃenter chｌoroｐhylｌs, P680 ａnd Ｐ７００，eacｈass

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ｏciated with ａn eｌectrｏn aｃcepｔorｍoｌeculｅand ａn el ｅctｒon donor.Tｈesｅａｇgrｅgａtiｏｎｓａreｋnoｗn res ｐectivｅly as photｏsyｓtem Ⅰ (P7０0) and pｈotosyｓtem Ⅱ(P68０）.

所有的光合作用生物含有不同等级的叶绿素和一个或多个类胡萝卜素（光合作用的辅助色素)。称作天线复合体的色素分子群存在于类囊体中。激活色素分子的光能进入叶绿素反应中心，其直接参与光合作用。大部分光反应细胞器拥有两套反应中心，P6８０和P700,每个光系统都含有一个电子受体和电子供体。这些集合体就是大家熟识的光合系统Ⅰ和光合系统Ⅱ。

ThｅLｉght-Dｅpenｄent Ｒeａction:Coｎverｔing Sｏlａr Enｅｒｇy inｔoＣhemicaｌ-Bond Eneｒｇy

光反应:光能转化成化学键能

The ｐhoｔosysｔems of thｅｌiｇht-ｄepｅｎｄｅnt reactｉoｎs a ｒe reｓponsibｌｅfor tｈe pａｃkａging of light energｙiｎthe ｃh ｅｍical comｐouｎds ATP aｎｄNAＤPH．Ｔhｉｓpackaging takesｐlａce tｈrough a seｒies of oxidatiｏn redｕctｉon ｒeactions set iｎmotiｏn ｗhen lｉghｔsｔrikeｓthe Ｐ68０ｒeacｔｉｏｎcenter in phoｔosyｓtemⅡ. In this inｉtiaｌev ｅnt water moｌecules aｒe cleavｅd，ｏxygeｎis reｌeaseｄ,and elｅcｔrons arｅdonated．Tｈｅsｅeleｃtronsａre acｃepteｄfirst byｐlasｔoquｉnｏneａnｄｔhen ｂy a series of caｒrierｓａｓtheｙdescend ａｎeｌectｒoｎtranspｏrt cｈain.For eac ｈfouｒｅlectrons that pass dｏwn the chain，two ATPｓar ｅfｏrmed. The laｓt acｃｅｐtorｉn the cｈain is thｅP7００re ａcｔion cenｔer of phoｔoｓysｔeｍⅠ. At this pｏiｎt iｎcoming phoｔoｎｓbｏosｔthe ｅneｒgy ofｔhｅelectronｓ,and tｈey are acｃepteｄby feｒredｏxin. Ｆeｒredoｘin is ｔheｎre ｏxidiｚｅｄ, anｄthe cｏenzymｅＮADP+is reduｃed ｔo tｈe NADPH. The ＡTP gｅneratｅd pｒevｉouｓly aｎd tｈe NＡDPH ｔhen taｋe parｔin the lighｔiｎｄepeｎdeｎｔreactiｏns.

光反应的光系统将光能转化成化学复合物ATP和ＮADPH。当光激活光系统Ⅱ的光反应中心时,通过一系列的氧化还原反应实现能量的传递。反应开始时,水被分解，氧被释放并提供电子。电子首先传递给质体醌，然后通过一系列载体形成的电子传递链。每传递4个电子，

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形成2个ATP。最后一个受体存在于光反应系统Ⅰ的反应中心里。此处光子激活电子,电子传递给铁氧还蛋白。铁氧还蛋白再氧化,并且辅酶NADP+还原成NADＰH。早期产生的AＴP和NADPH进入暗反应。The pｒoduｃtion of ATP fｒoｍｔhｅｔraｎｓｐort of ｅｌectrons ｅｘcitｅd by ligｈt eｎergy down aｎeleｃtron transｐort c ｈａin is terｍed pｈotｏphoｓphoｒylatioｎ. Tｈe one-wａy ｆｌo ｗofｅlｅctｒonｓthrough pｈoｔosyｓtems II anｄI is cａlled noncｙclic photophｏsphoｒylａtioｎ；planｔs aｌso ｄeｒｉｖe a ｄditioｎal AＴP throｕgh cycｌｉｃｐhotophoｓphｏrylatｉon,in ｗhich ｓome elｅcｔｒoｎs are ｓhｕnted bacｋtｈrough ｔhe eｌeｃｔｒoｎtranｓpoｒt cｈain between ｐhotosystemsⅡ anｄⅠ.

由电子传递链偶连产生ATP的过程称为光合磷酸化。通过光合系统Ⅱ流经光合系统Ⅰ的电子路径称非循环式光合磷酸化;植物通过循环式光合磷酸化获得额外的ＡTP，一些电子在光合系统Ⅰ和Ⅱ之间的电子传递链中回流。

The Light-Inｄeｐenｄｅnt Reａｃtiｏns:Buｉlｄing Carbｏhｙｄｒates

暗反应:碳水化合物的形成

Inｔhe ｌigｈt-indeｐeｎdent ｒeactionｓof phｏtosｙntｈesis, ｗhich are driven by ATP and NADPH, Ｃ０2ｉs cｏｎveｒtｅd to carbｏhyｄratｅ. The ｒｅａctioｎｓare also ｋnown ａs tｈe Caｌvｉn－Benson cycｌe．ＡtｍosｐheriｃCO2, ｉs fixed as it ｒeactｓwith rｉbｕｌose bipｈｏsphate （ＲuBP), a ｒｅaction ｔｈat iｓcａｔalyzeｄbyｔｈe ｅnｚyｍe rｉｂｕlosｅbiphosphate carbｏxｙｌａse．Ｔhｅreductｉon OfＣ02ｔoｃａrbohydraｔｅ(fruｃtose dｉphoｓｐｈａte) ｉs complｅｔed via ｓeverａｌmorｅsteps ｏｆｔｈe cyｃle. Fｉnalｌy, RUBＰｉs reｇenerａtｅd sｏthat thｅcｙcｌeｍaｙcｏｎtinｕｅ.

由ＡTＰ和NADＰH驱动的暗反应中，二氧化碳转化成碳水化合物。即卡尔文循环。二磷酸核酮糖固定二氧化碳,由二磷酸核酮糖羧化酶催化。

Oxyｇen：An Inhibitoｒof photosynｔｈesis（氧：光合作用的抑制因子）

High lｅｖels oｆoxygen in pｌant ceｌlｓｃａn ｄisrupt photosynｔhesis ａｎd can alｓo cａｕse ｐhｏｔoresｐiratioｎ-ａn i

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ｎｅｆｆｉcienｔfun ｏf ｔｈe dａrｋreａｃtions in ｗhiｃh 02 is fixeｄｒather ｔhan C０2 ａnd no cａrbohｙdrate ｉs proｄuceｄ.

Rｅpｒievｅfrｏm Photorespiration:Ｔhe C4 Paｔhｗay

Moｓｔｐlａnts aｒe C3 plantｓ; thｅｙexperieｎcｅdｅcｒea ｓeｄcarbohydrate prｏｄuctiｏn under hot，dry conditiｏｎs ａｓａresult of the eｆfecｔｓof pｈotｏrespiraｔion.AmonｇＣ4 plaｎts, hoｗever,sｐｅｃial lｅａf anａtomyａnｄ a uｎｉque biochｅmical pａｔhwaｙenａｂlｅｔhe planｔｔo ｔhrive in and ｃｏnditionｓ.ＴhuｓＣ４ｐlants leｓsen ｐｈotoｒespｉr ａtioｎby carｒyinｇouｔphoｔosyｎｔheｓis only in cｅlls that are insulated from high ｌevels ofＣＯ2．Theｙalso pｏsseｓs a novel ｍeｃhａnｉsm forｃarｂon fｉxａtioｎ．

大部分植物是碳３植物,在高温干旱条件下，由于光呼吸作用而使碳水化合物的合成降低。而在大多数的碳4植物中,由于叶脉的特殊构造和独特的化学路径使植物依然很茂盛。这是碳固定的一个新机制。?

课后作业:第一篇阅读材料

答案:1B,2A，３A，4Ｄ，5C,６c

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Glｏｓsar

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lｉght-dependenｔｒｅactiｏｎs光反应-

Tｈｅfirst staｇｅin photosynthesｉs, ｄriveｎｂy lighｔenerｇｙ.Ｅlｅctrons that tｒap tｈe sun's ene ｒgy pass the enｅrgｙｔo high-ｅnerｇy carriｅｒｓｓｕcｈasＡTP or NADＰＨ, wｈere it is storeｄiｎcｈemiｃal bｏndｓ．

ｌｉgｈt-indｅpendeｎt reacｔions 暗反应

The secoｎｄstage of phoｔｏsynｔhｅsｉs,alｓo calｌeｄthｅCａlｖin-Ｂeｎsoｎcyｃlｅ，which dｏeｓｎot requiｒｅlｉｇht. During thｅsix steｐs ofｔhe ｃycｌe, cａrboｎisｆiｘeｄand carｂｏｈydratｅs are formed.

chlｏropｌast 叶绿体

A ｐlasｔid ｉn whiｃh phoｔosyntｈｅsisｉs cａrｒied out. Cｈloroｐlasts occｕr in all ｐhotosｙｎthetiｃｏrganiｓms exｃept pｈotｏsynthｅtic bａｃteria and bluｅ-ｇｒeen ａlgae．

ａｂsoｒｐtｉon ｓｐectｒｕm 吸收光谱,吸收谱

Ｔhｅspectruｍobtaiｎed wheｎrａdｉａtion (lｉght, ultrａviolet radiaｔｉoｎ, etｃ.) ｆｒoｍa soｕrｃe ｇivinｇa contｉnuoｕs sｐｅｃtrumｉsｐasｓed ｔhrough a sｕbsｔａnce.

Ｃalvin-Bｅnsｏｎcｙclｅ卡尔文·本森循环

Cycｌic reactiｏns that are the ＂syntheｓis" paｒt of thｅlight-iｎdependent rｅａcｔｉonｓof photosynthesｉs．I ｎｌaｎｄplanｔs, ＲUBP, ｏr soｍe otｈer comｐoun ｄtｏwhich carｂｏn has

been affｉxed,ｕｎder goes rearrａngemenｔｓtｈat lｅa

ｄto ｆoｒｍａtion ｏf ａsuｇar phosphaｔe and tｏrｅgenｅrａtiｏn oｆtheＲUＢＰ. Ｔｈe ｃyclｅｒｕｎｓｏn ATＰaｎd NAＤPH ｆｒom light－depeｎｄｅnt reaｃtionｓ.

carotenoid 类胡萝卜素

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Ligｈt－ｓensiｔivｅ, aｃceｓsｏry pｉｇｍents that ｔrａnsfer absｏｒbｅｄeｎｅrgy to chｌoroｐｈylls.

Theyａｂsorb violet aｎｄblue wａve-lenｇthｓｂut t ｒansｍｉｔrｅd, orangｅ, ａnd yｅllow.

chｌorｏphyll 叶绿素

Tｈe gｒｅｅn subｓtａnce oｆpｌants by ｗhich photｏsynthesis ｉs ａcｃomｐｌished; ｉt iｓusuallｙloca ｌized iｎintracｅlｌｕlａr oｒganｅlles calleｄchｌｏroplａsts.

cｙcｌic pｈotｏphosphorｙlatｉon

环形光合磷酸化（作用)

Cycｌic photｏphｏsphorｙlaｔion is cｏupled to cycｌicelectron ｆlｏw, ｉn ｗhｉcｈATP isｔhe ｏnｌy ｐroduct.

C3 plant 三碳植物

A planｔin which thｅligｈt－inｄependenｔrｅa ｃtionｓof ｐhoｔoｓyntheｓis stａrｔwiｔｈaｔhre ｅcａrｂｏn coｍpouｎd. Mosｔplants aｒe C3plants. C4ｐlant 四碳植物

A plant ｓｕｃh ａs corｎｉn wｈich the ligｈt ｉn ｄｅpeｎdent reactions oｆphoｔosｙnthesis ｓｔar with a ｆouｒ-caｒbｏｎcomｐｏunｄ.

nｏncｙclic phｏtoｐhｏsphｏrｙlation

非环形光合磷酸化作用

Noｎcｙｃｌic photopｈosｐhoｒyｌatioｎis coupｌed ｔｏnonｃｙｃｌic elｅctｒoｎfｌoｗ, thｅｅlectroｎs beingｕsed to ｒｅｄuce NAＤＰ+ as well as to mａke A ＴＰ.

phoｔｏn光子

Ａpａrtiｃle thａt hａsｚｅrｏmass oｒcharｇe and ｕnit spin，the qｕantuｍof ｔｈe elｅcｔrｏmagｎetiｃfieｌd aｎd cａrrier of the elｅctrｏｍａgnetic ｆoｒce.

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ｐｈｏtophosｐhorylatiｏn 光合磷酸化作用

Ｔhe syｎtｈesiｓof ATP ｆｒom phosphate anｄAＤP ｄuring ｐhotosyｎthesis, ｕsｉｎg ｌighｔeｎｅrgy．

pｈotoｒｅspiｒatｉon 光呼吸

Ａlight-deｐeｎdｅｎt tｙpｅofｒeｓpiraｔioｎthat occurs in most phoｔｏsynthetic planｔs anｄdｉｆfeｒs frｏｍｎormａl (ｏr darｋ)rｅspiraｔｉoｎ.

ｐhotosynｔhesis 光合作用

The sｙnthesｉｓof oｒgａnic compoｕｎdｓby reduｃtion of carｂｏｎdioｘｉde using light eｎerｇy absoｒbｅd by chｏropｈｙｌl.

phｏtoｓyｓtｅm光合系统

Ｏne of thｅｃｌusters oｆliｇht-trａpping piｇｍeｎｔｓeｍbeddｅd in phｏtosyntｈeticｍeｍbｒanｅs. PhotoｓysteｍI opeｒates ｄuring thｅcｙclic paｔhway; photoｓyｓteｍⅡoｐｅratｅｓｄurinｇboth the cyclｉc ａnd noｎcｙｃlic ｐａthwaｙs．riｂulｏse biph ｏsphate(RUBＰ)核酮糖二磷酸

A ｃoｍｐｏund wｉth a bａcｋbone of five carbｏn atomｓtｈaｔisｒequired for caｒbｏｎfixation in ｔｈe Ｃalｖiｎ－Benｓon cycle of ｐhoｔosynｔhｅsis．

thｙlａkoid 类囊体

Oｎe ofａnumber of flatteneｄflｕid－fｉlled sacｓｔhat fｏｒm the phｏｔosyntｈｅｔic laｍeｌlａｒsｙsteｍoｆchloroｐlasts, photｏsyntheｔiｃbaｃteｒia, ａｎd bｌue-ｇreen algae.

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Cｅlluｌar Rｅproductｉon: Mｉtｏsｉｓａnd Mｅioｓis

Ｔｈe Nucleus anｄCｈrｏmosomeｓ

Ｔhe cell nｕcleus is the main ｒepｏsiｔory of geｎeｔic ｉnforｍaｔiｏn．Wiｔhｉn thｅnuclｅus ａrｅthｅcｈｒomosomeｓtigｈtlｙｃｏiled straｎｄs of DNA and cluｓteｒs of ａｓsocｉateｄproteｉns. Lｏng stｒetches of thｅｃｏｎtinｕｏｕs DNＡmolecｕle wind arounｄthｅｓe cluｓteｒs ｏf prｏteins,or hｉｓｔoｎes,fｏｒmｉng beadlike cｏｍplexes knowｎas nucｌeoｓomes. Ｍoｒe coｉling aｎd supercoｉｌing proｄｕｃeｓa deｎｓe chromoｓomｅstruｃturｅ.Eacｈlong strand of DNA combineｓwitｈhistoｎｅs anｄnｏnhistonｅｐrｏtｅinｓto ｍａkｅupｔhe suｂｓtaｎce chromａtiｎ.

细胞核是贮藏遗传信息的主要场所。DNA盘绕成螺旋线以及相关的成簇蛋白质。DＮA螺旋线缠绕成簇的组蛋白形成珠链状的核小体。

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这些螺旋和超螺旋形成致密的染色体组结构。每个长链DＮＡ与组蛋白和非组蛋白一起构成染色质物质。

A ｐiｃtorial diｓpｌay ｏf an oｒgaｎｉsｍ's cｈroｍosｏmes ｉn the ｃoilｅd, cｏｎdensed staｔe ｉs kｎoｗn as a kａryｏtype.Ｋaryｏtype reｖｅaｌthａt iｎmoｓt celｌs all but sex ｃhｒom ｏsｏmes aｒｅprｅsｅnt asｔwｏcopies, referred ｔo aｓhomologous pａirｓ.Non-sex cｈromｏsoｍes arｅｃalled aｕtosomｅ3b2770da5d0e7cd184254b35eefdc8d377ee1452ａniｓms whｏsｅcells conｔaiｎtwｏsｅｔs of pａreｎtaｌchromosomｅs are ｃaｌlｅdｄiploid; thosｅｗith ｃells containiｎｇa sｉngle ｓet of pareｎtａl chｒomosomes ａre calｌed haｐloid.

染色体致密的超螺旋状态我们称染色体组。除了性染色体外,大多数细胞的染色体组成对出现，称同源染色体对。非性染色体称常染色体。生物细胞含有两套父母本染色体的称二倍体；含有单套染色体的称单倍体。

The CｅlｌＣｙｃｌe

The ceｌl cyclｅis a regular sｅquence in ｗhicｈtｈeｃell grows,prepaｒes ｆｏr dｉvisiｏｎ,ａndｄｉviｄes to forｍt ｗo dａughter ceｌlｓ, each of whｉch thｅｎrｅｐeatsｔhe cyｃl ｅ．Ｓuｃh ｃycling in efｆect makes ｓingle-celｌeｄｏrganiｓms imｍortal. Mａny cｅlls in mｕlticｅllｕlａr ｏrganｉsmｓ,inclu ｄiｎg ａniｍaｌmuｓcle aｎd nerve ceｌls，ｅither slow the cycl ｅoｒbｒｅak ｏut oｆiｔalｔｏgetｈer.

在细胞生长过程中,细胞循环遵循特定程序，分裂准备，分裂成２个子细胞，子细胞再循环。此循环使得单细胞永生。多细胞生物中的许多细胞，包括动物肌肉和神经细胞,要么降低循环速度，要么同时分裂。

Ｔhｅnｏrmal cｅll ｃyｃle consistｓof fouｒｐｈａses．Ｔhｅfｉｒst three incluｄe G１，the perｉod of ｎormａl me ｔaｂolｉｓm; S phase,durｉｎg whｉｃh ｎorｍal ｓyntｈesis of biolｏgiｃal ｍolecules cｏｎtinues, DNA is rｅplicａted, aｎd histones are syｎtｈesｉzeｄ; and G２, a brief perｉod ｏｆｍetａｂolｉｓmａnd adｄitional gｒｏｗth. Together tｈe Ｇ1, Ｓ，and G2phases are calｌed ｉｎｔerphase．Tｈeｆourth phase of ｔhｅcｅｌｌcyｃｌe ｉs M phase, the pｅｒiod of

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