生物专业英语第三版蒋悟生编课文翻译及课后单词Word格式.docx
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FunctionofInternalCellParts
Cytoplasm:
TheDynamic,MobileFactory细胞质:
动力工厂
Mostofthepropertiesweassociatewithlifearepropertiesofthecytoplasm.Muchofthemassofacellconsistsofthissemifluidsubstance,whichisboundedontheoutsidebytheplasmamembrane.Organellesaresuspendedwithinit,supportedbythefilamentousnetworkofthecytoskeleton.Dissolvedinthecytoplasmicfluidarenutrients,ions,solubleproteins,andothermaterialsneededforcellfunctioning.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。
TheNucleus:
InformationCentral(细胞核:
信息中心)
Theeukaryoticcellnucleusisthelargestorganelleandhousesthegeneticmaterial(DNA)onchromosomes.(Inprokaryotesthehereditarymaterialisfoundinthenucleoid.)Thenucleusalsocontainsoneortwoorganelles-thenucleoli-thatplayaroleincelldivision.Apore-perforatedsaccalledthenuclearenvelopeseparatesthenucleusanditscontentsfromthecytoplasm.Smallmoleculescanpassthroughthenuclearenvelope,butlargermoleculessuchasmRNAandribosomesmustenterandexitviathepores.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:
SpecializedWorkUnits(细胞器:
特殊的功能单位)
Alleukaryoticcellscontainmostofthevariouskindsoforganelles,andeachorganelleperformsaspecializedfunctioninthecell.Organellesdescribedinthissectionincluderibosomes,theendoplasmicreticulum,theGolgicomplex,vacuoles,lysosomes,mitochondria,andtheplastidsofplantcells.
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,Thisquantityreflectsthefactthat,ribosomesarethesitesatwhichaminoacidsareassembledintoproteinsforexportorforuseincellprocesses.Acompleteribosomeiscomposedofonelargerandonesmallersubunit.DuringproteinsynthesisthetwosubunitsmovealongastrandofmRNA,&
quot;
reading&
thegeneticsequencecodedinitandtranslatingthatsequenceintoprotein.SeveralribosomesmaybecomeattachedtoasinglemRNAstrand;
suchacombinationiscalledapolysome.Mostcellularproteinsaremanufacturedonribosomesinthecytoplasm.Exportableproteinsandmembraneproteinsareusuallymadeinassociationwiththeendoplasmicreticulum.
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Bothtypesplayrolesinthesynthesisandtransportofproteins.TheRER,whichisstuddedwithpolysomes,alsoseemstobethesourceofthenuclearenvelopeafteracelldivides.Bothtypesofendoplasmicreticulumserveascompartmentswithinthecellwherespecificproductscanbeisolatedandsubsequentlyshuntedtoparticularareasinor
1
outsidethecell.光滑WithintheGolgicomplexmoleculesaremodifiedandpackagedforexportoutofthecellorfordeliveryelsewhereinthecytoplasm.
运输小泡能够将可运输分子从Themostprominentvacuolesappearinplantcellsandserveaswaterreservoirsandstoragesitesforsugarsandothermolecules.Vacuolesinanimalcellscarryoutphagocytosis(theintakeofparticulatematter)andpinocytosis(vacuolardrinking).
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。
Asubsetofvacuolesaretheorganellesknownaslysosomes,whichcontaindigestiveenzymes(packagedinlysosomesintheGolgicomplex)thatcanbreakdownmostbiologicalmacromolecules.Theyacttodigestfoodparticlesandtodegradedamagedcellparts.
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。
Mitochondriaarethesitesofenergy-yieldingchemicalreactionsinallcells.Inaddition,plantcellscontainplastidsthatutilizelightenergytomanufacturecarbohydratesintheprocessofphotosynthesis.ItisonthelargesurfaceareaprovidedbytheinnercristaeofmitochondriathatATP-generatingenzymesarelocated.Mitochondriaareself-replicating,andprobablytheyaretheevolutionarydescendantsofwhatwereoncefree-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Themostimportantchromoplastsarechloroplasts-organellesthatcontainthechlorophyllusedinphotosynthesis.Theinternalstructureofchloroplastsincludesstacksofmembranescalledgrana,whichareembeddedinamatrixcalledthestroma.
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Alargeportionofthecytoskeletonconsistsofthreadlikemicrofilamentscomposedmainlyofthecontractileproteinactin.Theyareinvolvedinmanytypesofintracellularmovementsinplantandanimalcells.Asecondprotein,myosin,isinvolveinthecontractionofmusclecells.Anothermainstructuralcomponentofthecytoskeletonconsistsofmicrotubules,whicharecomposedoftheglobularproteintubulinandtogetheractasscaffoldingthatprovidesast