生物專業(yè)英語翻譯+蔣悟生+第3版

1、Lesson One（4學(xué)時(shí)）Inside the Living Cell: Structure andFunction of Internal Cell Parts1.Cytoplasm: The Dynamic, Mobile Factory細(xì)胞質(zhì)：動(dòng)力工廠Most of the properties we associate with life are properties of the cytoplasm. Much of t

2、he mass of a cell consists of this semifluid substance, which is bounded on the outside by the plasma membrane. Organelles are suspended within it, supported by the filamentous network of the cytoskeleton. Dissolved in

3、 the cytoplasmic fluid are nutrients, ions, soluble proteins, and other materials needed for cell functioning.生命的大部分特征表現(xiàn)在細(xì)胞質(zhì)的特征上。細(xì)胞質(zhì)大部分由半流體物質(zhì)組成，并由細(xì)胞膜（原生質(zhì)膜）包被。細(xì)胞器懸浮在其中，并由絲狀的細(xì)胞骨架支撐。細(xì)胞質(zhì)中溶解了大量的營養(yǎng)物質(zhì)，離子，可溶蛋白以及維持細(xì)胞生理需求的其它物質(zhì)。2．T

4、he Nucleus: Information Central（細(xì)胞核：信息中心）The eukaryotic cell nucleus is the largest organelle and houses the genetic material (DNA) on chromosomes. (In prokaryotes the hereditary material is found in the nucleoid.) The n

5、ucleus also contains one or two organelles-the nucleoli-that play a role in cell division. A pore-perforated sac called the nuclear envelope separates the nucleus and its contents from the cytoplasm. Small molecules ca

6、n pass through the nuclear envelope, but larger molecules such as mRNA and ribosomes must enter and exit via the pores.真核細(xì)胞的細(xì)胞核是最大的細(xì)胞器，細(xì)胞核對(duì)染色體組有保護(hù)作用（原核細(xì)胞的遺傳物質(zhì)存在于擬核中）。細(xì)胞核含有一或二個(gè)核仁，核仁促進(jìn)細(xì)胞分裂。核膜貫穿許多小孔，小分子可以自由通過核膜，而象mRNA和核糖體等大

7、分子必須通過核孔運(yùn)輸。3.Organelles: Specialized Work Units（細(xì)胞器：特殊的功能單位）All eukaryotic cells contain most of the various kinds of organelles, and each organelle performs a specialized function in the cell. Organelles described in

8、this section include ribosomes, the endoplasmic reticulum, the Golgi complex, vacuoles, lysosomes, mitochondria, and the plastids of plant cells.所有的真核細(xì)胞都含有多種細(xì)胞器，每個(gè)細(xì)胞器都有其特定功能。本節(jié)主要介紹核糖體，內(nèi)質(zhì)網(wǎng)，高爾基體系，液泡，溶酶體，線粒體和植物細(xì)胞中的質(zhì)體。The nu

9、mber of ribosomes within a cell may range from a few hundred to many thousands. This quantity reflects the fact that, ribosomes are the sites at which amino acids are assembled into proteins for export or for use in cel

10、l processes. A complete ribosome is composed of one larger and one smaller subunit. During protein synthesis the two subunits move along a strand of mRNA, “reading“ the genetic sequence coded in it and translating that

11、 sequence into protein. Several ribosomes may become attached to a single mRNA strand; such a combination is called a polysome. Most cellular proteins are the inner cristae of mitochondria that ATP-generating enzymes

12、are located. Mitochondria are self-replicating, and probably they are the evolutionary descendants of what were once free-living prokaryotes.線粒體是細(xì)胞中化學(xué)產(chǎn)能的場(chǎng)所。另外，植物細(xì)胞中的質(zhì)體在光合作用中利用光能產(chǎn)生碳水化合物，線粒體內(nèi)嵴上提供了很大的表面積并分布著產(chǎn)ATP酶。線粒體自我復(fù)制，并

13、且可能是自由生活的原核生物在進(jìn)化中形成的后代。There are two types of plastids: leucoplasts, which lack pigments and serve as storage sites for starch, proteins, and oils; and chromoplasts, which contain pigments. The most important chromopla

14、sts are chloroplasts-organelles that contain the chlorophyll used in photosynthesis. The internal structure of chloroplasts includes stacks of membranes called grana, which are embedded in a matrix called the stroma.質(zhì)體有

15、兩種類型：白色體，缺乏色素，是淀粉，蛋白質(zhì)和油的儲(chǔ)備場(chǎng)所；色質(zhì)體，含有色素。葉綠體是最重要的色質(zhì)體，含有與光合作用有關(guān)的葉綠素。葉綠體的內(nèi)部結(jié)構(gòu)是由多層膜形成的葉綠體基粒，其中包埋在基質(zhì)中的基粒稱子座。4.The Cytoskeleton（細(xì)胞骨架）All eukaryotic cells have a cytoskeleton, which is a convoluted latticework of filaments and tu

16、bules that appears to fill all available space in the cell and provides support for various other organelles. A large portion of the cytoskeleton consists of threadlike microfilaments composed mainly of the contractile

17、protein actin. They are involved in many types of intracellular movements in plant and animal cells. A second protein, myosin, is involve in the contraction of muscle cells. Another main structural component of the cy

18、toskeleton consists of microtubules, which are composed of the globular protein tubulin and together act as scaffolding that provides a stable cell shape. Cytoskeletal intermediate filaments appear to impart tensile st

19、rength to the cell cytoplasm. Mechanoenzymes such as myosin, dynein, and kinesin interact with the cytoskeletal filaments and tubules to generate forces that cause movements.所有的細(xì)胞都有細(xì)胞骨架，網(wǎng)絡(luò)結(jié)構(gòu)的纖絲充滿了它所能觸及的全部空間并且對(duì)細(xì)胞器提供支持作用。

20、細(xì)胞骨架大部分由微絲組成，微絲主要由可收縮的肌動(dòng)蛋白組成。動(dòng)植物細(xì)胞的許多種類型細(xì)胞內(nèi)運(yùn)動(dòng)與肌動(dòng)蛋白有關(guān)。第二類蛋白是肌球蛋白，它與肌肉細(xì)胞的收縮有關(guān)。細(xì)胞骨架的另一個(gè)主要結(jié)構(gòu)成分是微管，由球狀的微管蛋白組成，象腳手架一般維持細(xì)胞的穩(wěn)定形態(tài)。細(xì)胞骨架的中間絲提供了細(xì)胞質(zhì)伸縮動(dòng)力。機(jī)械酶，例如，肌球蛋白，動(dòng)力蛋白，驅(qū)動(dòng)蛋白與微絲，微管相互作用產(chǎn)生動(dòng)力而引起細(xì)胞運(yùn)動(dòng)。5.Cellular Movements（細(xì)胞運(yùn)動(dòng) Although th

21、e cytoskeleton provides some stability穩(wěn)固 to cells, its microtubules英[?maikr?u?tju:bju:l ?maikr?u?tju:bju:l] and filaments 絲狀物 and their associated proteins enable cells to move by creeping 爬行 or gliding 滑動(dòng). Such moveme

22、nts require a solid固體的 substrate to which the cell can adhere附著 and can be guided by the geometry d?i??mitri d?i??mitri] 幾何形狀of the surface. Some cells also exhibit [iɡ?zibit iɡ?zibit] 展覽 chemotaxis, kem??tæksis k