生物专业英语第三版蒋悟生编--课文翻译

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

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 divｉdｅｓ.