生物专业英语第三版蒋悟生编课文翻译Word文件下载.docx

1、 The Dyn amic, Mobile Factory 细胞质：动力工厂Most of the properties we associatewith life are properties of the cytoplasm. Much of the mass of a cell consists of this semifluid substanee, which is bounded on the outside by the plasma membrane. Organelles are suspended within it,supported by the filamentous

2、 network of the cytoskeleton. Dissolved in the cytoplasmic fluid are nutrients, ions, soluble prote ins, and other materials n eeded for cell fun cti oning. 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: In formation Central

3、 （细胞核：信息中心）The eukaryotic cell nucleusis the largest orga nelle and houses the gen etic material （DNA） on chromosomes（l n prokaryotes the hereditary material is found in the nucleoid ）The nu cleus also contains one or two orga nelles-thenucleolithat play a role in cell division. A pore-perforated sa

4、c called the nuclear envelopeseparates the nu cleus and its contents from the cytoplasm. Small molecules can pass through the nuclear envelope, but larger molecules such as mRNA and ribosomes must en ter 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

5、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。Orga nelles: Specialized Work Un its （细胞器：特殊的功能单位）All eukaryotic cells contain most of the various kinds of orga nelles, and each orga nelle performs a specialized fun cti on in the cell. Orga nelles described in this secti on in elude ribosomes, the endop

6、lasmic reticulum, the Golgi complex, vacuoles, lysosomes, mitoch on dria, and the plastids of pla nt 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 nu mber of ribosomeswithi n a cell may range from a few hundred to many thousands. This quantity reflects the fact tha

7、t, ribosomes are the sites at which amino acids are assembledi nto proteins for export or for use in cell processes. A complete ribosome is composed of one larger and one smaller subunit. During protein syn thesis the two sub un its move along a stra nd of mRNA, readi ng the gen etic seque nee coded

8、 in it and tran slat ing that sequenee into protein. Several ribosomes may become attached to a sin gle mRNA stra nd; such a comb in ati on is called a polysome. Most cellular proteins are manufactured onribosomes in the cytoplasm. Exportable protei ns and membra ne proteins are usually made in asso

9、ciation with the endoplasmic 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 体沿看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 lacy array of membra nous sacs, tubules, and vesicles, may be either rough （RER） or smooth （

10、SER）. Both types play roles in the syn thesis and tran sport of prote ins. The RER, which is studded with polysomes, also seems to be the source of the nu clear en velope after a cell divides.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 lacks polysomes; it is

11、 active in the syn thesis of fats and steroids and in the oxidati on of toxic substa nces in the cell. Both types of en doplasmic reticulum serve as compartme nts withi n the cell where specific products can be isolated and subsequently shu nted to particular areas in or outside the cell.光滑内质网上无核糖体，

12、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。Tran sport vesicles may carry exportable molecules from the en doplasmic reticulum to ano ther membra nous orga nelle, the Golgi complex. Within the Golgi complex molecules are modified and packaged for export out of the cell or for delivery else

13、 where in the cytoplasm.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。Vacuoles in cells appear to be hollow sacs but are actually filled with fluid and soluble molecules. The most prominent vacuoles appear in pla nt cells and serve as water reservoirs and storage sites for sugars and

14、other molecules. Vacuoles in animal cells carry out phagocytosis （the in take of particulate matter） and pinocytosis（vacuolar drinkin g）.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。A subset of vacuoles are the organelles known as lysosomes, which contain digestive en zyme

15、s （packaged in lysosomes in the Golgi complex） that can break down most biological macromolecules. They act to digest food particles and to degrade damaged cell parts.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 of energy-yielding chemical reacti ons in all cells. In addit

16、i on, pla nt cells contain plastids that utilize light en ergy to manu facture carbohydrates in the process of photosynthesis. It is on the large surface area provided by the inner cristae of mitochondria that ATP-generating enzymes are located. Mitoch on dria are self-replicati ng, and probably they are the evolutionary descendants of what w