生物專業(yè)英語蔣悟生編課文翻譯

1、Inside the Living Cell: Structure andFunction of Internal Cell PartsCytoplasm: The Dynamic, Mobile Factory細(xì)胞質(zhì)：動力工廠Most of the properties we associate with life are properties of the cytoplasm. Much of the mass of a cell consists of this semifluid substance, which is bounded on the outside by the pla

2、sma membrane. Organelles are suspended within it, supported by the filamentous network of the cytoskeleton. Dissolved in 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)

3、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)。The 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 nucleus also contains one or two organelles

4、-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 can 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

5、細(xì)胞核是最大的細(xì)胞器，細(xì)胞核對染色體組有保護(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和核糖體等大分子必須通過核孔運(yùn)輸。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 d

6、escribed in 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 number of ribosomes within a cell may range from a few hundred to many

7、 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 cell processes. A complete ribosome is composed of one larger and one smaller subunit. During protein synthesis the two subunits move along a strand of

8、mRNA, reading the genetic sequence coded in it and translating that sequence into protein. Several ribosomes may become attached to a single mRNA strand; such a combination is called a polysome. Most cellular proteins are manufactured on ribosomes in the cytoplasm. Exportable proteins and membrane p

9、roteins are usually made in association with the endoplasmic reticulum.核糖體的數(shù)量變化從幾百到幾千，核糖體是氨基酸組裝成蛋白質(zhì)的重要場所。完整的核糖體由大亞基和小亞基組成。核糖體沿著mRNA移動并閱讀遺傳密碼，翻譯成蛋白質(zhì)。一條mRNA上可能有多個核糖體，稱多聚核糖體。大多數(shù)細(xì)胞蛋白是由細(xì)胞質(zhì)中核糖體生產(chǎn)。輸出蛋白和膜蛋白通常與內(nèi)質(zhì)網(wǎng)有關(guān)。The endoplasmic reticulum, a lacy array of membranous sacs, tubules, and vesicles, may be eit

10、her rough (RER) or smooth (SER). Both types play roles in the synthesis and transport of proteins. The RER, which is studded with polysomes, also seems to be the source of the nuclear envelope after a cell divides.內(nèi)質(zhì)網(wǎng)，帶有花邊的生物囊，有管狀，泡狀之分，以及光滑和粗糙面區(qū)別。兩種都與蛋白質(zhì)的合成和運(yùn)輸有關(guān)。粗糙內(nèi)質(zhì)網(wǎng)上分布許多核糖體，也可能提供細(xì)胞分裂后所需的細(xì)胞膜。SER la

11、cks polysomes; it is active in the synthesis of fats and steroids and in the oxidation of toxic substances in the cell. Both types of endoplasmic reticulum serve as compartments within the cell where specific products can be isolated and subsequently shunted to particular areas in or outside the cel

12、l.光滑內(nèi)質(zhì)網(wǎng)上無核糖體，主要作用是脂肪和類固醇的合成以及細(xì)胞內(nèi)有毒物質(zhì)的氧化。兩種內(nèi)質(zhì)網(wǎng)合成的產(chǎn)物在其中進(jìn)行分流或運(yùn)輸?shù)郊?xì)胞外。Transport vesicles may carry exportable molecules from the endoplasmic reticulum to another membranous organelle, the Golgi complex. Within the Golgi complex molecules are modified and packaged for export out of the cell or for deliver

13、y else where in the cytoplasm.運(yùn)輸小泡能夠?qū)⒖蛇\(yùn)輸分子從內(nèi)質(zhì)網(wǎng)運(yùn)輸?shù)礁郀柣鶑?fù)合體上。在高爾基復(fù)合體中修飾，包裝后輸出細(xì)胞或傳遞到細(xì)胞質(zhì)中的其他場所。Vacuoles in cells appear to be hollow sacs but are actually filled with fluid and soluble molecules. The most prominent vacuoles appear in plant cells and serve as water reservoirs and storage sites for sugars a

14、nd other molecules. Vacuoles in animal cells carry out phagocytosis (the intake of particulate matter) and pinocytosis (vacuolar drinking).細(xì)胞中的液泡好象是中空的，但實(shí)際上充滿了液體和可溶分子。最典型的液泡存在于植物細(xì)胞中，儲備水，糖以及其它分子。動物中的液泡起吞噬和胞飲作用。 A subset of vacuoles are the organelles known as lysosomes, which contain digestive enzyme

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.溶酶體是液泡亞單位，含有消化酶，降解大部分生物大分子。消化食物微粒和降解損傷的細(xì)胞殘片。Mitochondria are the sites of energy-yielding chemical reactions in all cells. In additio

16、n, plant cells contain plastids that utilize light energy to manufacture 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. Mitochondria are self-replicating, and probably they are the

17、 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 ch

18、romoplasts, which contain pigments. The most important chromoplasts 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)體有兩種類型：白色體，缺乏色素，是淀粉

19、，蛋白質(zhì)和油的儲備場所；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。The Cytoskeleton（細(xì)胞骨架）All eukaryotic cells have a cytoskeleton, which is a convoluted latticework of filaments and tubules that appears to fill all available space in the cell and provides support for various other o

20、rganelles. A large portion of the cytoskeleton consists of threadlike microfilaments composed mainly of the contractile 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. Anothe

21、r main structural component of the cytoskeleton 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 strength to the cell cytoplasm. Mechanoenzymes

22、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細(xì)胞器提供支持作用。細(xì)胞骨架大部分由微絲組成，微絲主要由可收縮的肌動蛋白組成。動植物細(xì)胞的許多種類型細(xì)胞內(nèi)運(yùn)動與肌動蛋白有關(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

23、中間絲提供了細(xì)胞質(zhì)伸縮動力。機(jī)械酶，例如，肌球蛋白，動力蛋白，驅(qū)動蛋白與微絲，微管相互作用產(chǎn)生動力而引起細(xì)胞運(yùn)動。Cellular Movements（細(xì)胞運(yùn)動 Although the cytoskeleton provides some stability穩(wěn)固 to cells, its microtubules英maikrutju:bju:l and filaments 絲狀物 and their associated proteins enable cells to move by creeping 爬行 or gliding 滑動. Such movements require a

24、solid固體的 substrate to which the cell can adhere附著 and can be guided by the geometry dimitri 幾何形狀of the surface. Some cells also exhibit izibit 展覽 chemotaxis, kemtksis趨藥性 the ability to move toward or away from the source of a diffusing 擴(kuò)散 chemical.盡管細(xì)胞骨架提供了細(xì)胞的某些穩(wěn)定性，微絲，微管及相關(guān)蛋白能使細(xì)胞爬行或滑動。這種運(yùn)動需要固體基質(zhì)依托并通

25、過表面幾何形狀的改變而運(yùn)動。某些細(xì)胞具備趨藥性，即趨向或逃離擴(kuò)散開的化學(xué)源。Certain eukaryotic cells can swim freely in liquid environments, propelled by whiplike cilia sili纖毛or flagella 英fldel鞭毛. Both cilia and flagella have the same internal structure: nine doublets (pairs of microtubules) are arranged in a ring and extend the length

26、of the cilium or flagellum, and two more microtubules run down the center of the ring. Every cilium or flagellum grows only from the cell surface where a basal body基體is located. Movement is based on the activities of tiny dynein動力蛋白 side arms that extend from one of the microtubules of each doublet成

27、對的東西.某些真核細(xì)胞能在液體液體中自由運(yùn)動，由纖毛或鞭毛推動。纖毛和鞭毛具有同樣的內(nèi)部結(jié)構(gòu)：九個雙微管環(huán)形排列，縱向延伸，環(huán)中心是兩個或以上微管組成。纖毛或鞭毛從細(xì)胞表面的基體出生長，雙微管的動力蛋白臂從一側(cè)延伸到另一側(cè)而引起運(yùn)動。Nutrients, proteins, and other materials within most plant cells are moved about via cytoplasmic streaming. The process occurs as myosin maiusin肌凝蛋白 proteins attached to organelles 細(xì)胞

28、器,小器官 push against microfilaments arrayed rei 展示throughout the cell. Microfilaments and microtubules are responsible for almost all major cytoplasmic movements. During cell division, microtubules of the spindle assembled 集合, 收集 from tubutin subunits near organelles called centrioles move the chromos

29、omes. 大部分植物細(xì)胞的營養(yǎng)，蛋白質(zhì)和其它物質(zhì)由細(xì)胞質(zhì)流運(yùn)輸。這個過程是由于依附在細(xì)胞器上的肌球蛋白反推排列在細(xì)胞周圍的微絲形成的。絕大部分細(xì)胞質(zhì)運(yùn)動由微絲和微管完成。在細(xì)胞分裂期間，中心粒周圍的由微管蛋白亞基裝配形成的紡錘體微管移向染色體。Glossarycytoplasm （細(xì)）胞質(zhì)The living contents of a cell bounded externally by the plasmalemma, including an aqueous ground substance (hyaloplasm, cell sap, or cell matrix) containi

30、ng organelles and various inclusions but excluding the nucleus and visible vacuoles.cytoskeleton 細(xì)胞骨架Of eukaryotic cells, an internal skeleton. Its microtubules and other components structurally support the cell, organize and move its inteftial components. The cytoskeleton also helps free-living cel

31、ls move through their environment. nucleus 細(xì)胞核，核(復(fù)數(shù) nuclei)The organelle of the eukaryote cell that contains the chromosomes and hence ultimately controls cellular activity and inheritance through the activity of the genetic material, DNAchromosome 染色體A DNA-histone thread residing in the nucleus of

32、a cell. Each chromosome possesses two telomeres and a centromere, and some contain a nucleolus organizer. RNA proteins are invariably associated with the chromosome. nucleoid 擬核，類核，核質(zhì)體The DNA-containing area of a prokaryote cell, analogous to the eukaryote nucleus but not membrane bounded.nucleoli 核

33、仁( 單數(shù)nucleolus) Nuclear structures composed of completed or partially completed ribosomes and the specific parts of chromosomes that contain the infon-nation for their construction. nuclear envelope 核膜，核被膜A double membrane (two lipid bilayers and associated proteins) that is the outermost portion of

34、 a cell nucleus. ribosome 核糖體Small structures composed of two protein and ribonucleic acid subunits involved in the assembly of proteins from amino acids.polysome 多核糖體Of protein synthesis, several ribosomes all translating the same messenger RNA molecule,one after the other.endoplasmic reticulum 內(nèi)質(zhì)網(wǎng)

35、Folded membranes and tubes throughout the eukaryotic cell that provide a large surface upon which chemical activities take place.Golgi complex 高爾基復(fù)合體A stack of flattened, smooth, membranous sacs; the site of synthesis and packaging of certain molecules in eukaryotic cells.vacuole 液泡Storage container

36、 within the cytoplasm of a cell having a surrounding membrane.phagocytosis 吞噬作用The process by which the cell wraps around a particle and engulfs it.pinocytosis 胞飲作用The process by which a cell engulfs some molecules dissolved in waterlysosome 溶酶體A specialized organelle that holds a mixture of hydroly

37、tic enzymes.mitochondrion 線粒體(復(fù)數(shù) mitochondria )A membranous organelle resembling a small bag with a larger bag resembling a small bag with a larger bag inside that is folded back on itself; serves as the site of aerobic cellular respiration.plastid 質(zhì)體An organelle present in all plants except bacteri

38、a, blue-green algae, and fungi; it is enclosed by two membranes (the envelope) and has various functionschloroplast 葉綠體A plastid in which photosynthesis is carried out. Chloroplasts occur in all photosynthetic organisms except photosynthetic bacteria blue-green algae.stroma 基質(zhì)，子座（復(fù)數(shù) stromata）Region

39、within a chloroplast that has no chlorophyll.microfilament 微絲，纖絲Long, fiberlike structures made of protein and found in cells, often in close association with the microtubules; provide structural support and enable movement.actin 肌動蛋白 A globular contractile protein. In muscle cells, actin interacts

40、with another protein, myosin, to bring about contraction. myosin maiesin 肌球蛋白A protein that, with actin, constitutes the principal element of the contractile apparatus of muscle.microtubute 微管Small, hollow tubes of protein that function throughout the cytoplasm to provide structural support and enab

41、le movement.tubulin 微管蛋白A protein that is the major constituent of microtubules.dynein 動力蛋白，動素A group of at least four distinct proteins found in the flagella and microtubules of eukaryotic cells and possessing ATPase activity. chemotaxis 趨化性A locomotory movement of an organism or cell in response t

42、o, and directed by, an directional stimulus.cilia 纖毛Numerous short, hairlike structures projecting from the cell surface that enable locomotion. flagella 鞭毛 (單數(shù)flagellum) Long, hairlike structures projecting from the cell surface that enable locomotion.basal body 基體A body identical in structure to a

43、 centriole, found always at the base of a cilium or eukaryote flagellum.centriole 中心粒 An organelle located close to the nucleus in most animal and lower plant cells but absent from prokaryotes and higher plants.PhotosynthesisPhotosynthesis occurs only in the chlorophyllchlorophyll葉綠素-containing cell

44、s of green plants, algae藻, and certain protists 原生生物and bacteria. Overall, it is a process that converts light energy into chemical energy that is stored in the molecular bonds. From the point of view of chemistry and energetics, it is the opposite of cellular respiration. Whereas 然而 cellular細(xì)胞的 res

45、piration 呼吸is highly exergonic吸收能量的 and releases energy, photosynthesis光合作用 requires energy and is highly endergonic.光合作用只發(fā)生在含有葉綠素的綠色植物細(xì)胞，海藻，某些原生動物和細(xì)菌之中?？傮w來說，這是一個將光能轉(zhuǎn)化成化學(xué)能，并將能量貯存在分子鍵中，從化學(xué)和動能學(xué)角度來看，它是細(xì)胞呼吸作用的對立面。細(xì)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過程。Photosynthesis starts with CO2 and H2O as raw materials and p

46、roceeds through two sets of partial reactions. In the first set, called the light-dependent reactions, water molecules are split裂開 (oxidized), 02 is released, and ATP and NADPH are formed. These reactions must take place in the presence of 在面前 light energy. In the second set, called light-independen

47、t reactions, CO2 is reduced (via the addition of H atoms) to carbohydrate. These chemical events rely on the electron carrier NADPH and ATP generated by the first set of reactions.光合作用以二氧化碳和水為原材料并經(jīng)歷兩步化學(xué)反應(yīng)。第一步，稱光反應(yīng)，水分子分解，氧分子釋放，ATP和NADPH形成。此反應(yīng)需要光能的存在。第二步，稱暗反應(yīng)，二氧化碳被還原成碳水化合物，這步反應(yīng)依賴電子載體NADPH以及第一步反應(yīng)產(chǎn)生的ATP

48、。Both sets of reactions take place in chloroplasts. Most of the enzymes and pigments 色素for the lightdependent reactions are embedded 深入的 內(nèi)含的in the thylakoid類囊體 membrane膜 隔膜 of chloroplasts 葉綠體. The dark reactions take place in the stroma.基質(zhì) 兩步反應(yīng)都發(fā)生在葉綠體中。光反應(yīng)需要的大部分酶和色素包埋在葉綠體的類囊體膜上。暗反應(yīng)發(fā)生在基質(zhì)中。How Light

49、Energy Reaches Photosynthetic Cells（光合細(xì)胞如何吸收光能的）The energy in light photons in the visible part of the spectrum can be captured by biological molecules to do constructive work. The pigment chlorophyll in plant cells absorbs photons within a particular absorption spectrums statement of the amount of

50、light absorbed by chlorophyll at different wavelengths. When light is absorbed it alters the arrangement of electrons in the absorbing molecule. The added energy of the photon boosts the energy condition of the molecule from a stable state to a less-stable excited state. During the light-dependent r

51、eactions of photosynthesis, as the absorbing molecule returns to the ground state, the excess excitation energy is transmitted to other molecules and stored as chemical energy.生物分子能捕獲可見光譜中的光能。植物細(xì)胞中葉綠素在不同光波下吸收部分吸收光譜。在吸收分子中，光的作用使分子中的電子發(fā)生重排。光子的能量激活了分子的能量狀態(tài)，使其從穩(wěn)定態(tài)進(jìn)入不穩(wěn)定的激活態(tài)。All photosynthetic organisms c

52、ontain various classes of chlorophylls and one or more carotenoid (accessory) pigments that also contribute to photosynthesis. Groups of pigment molecules called antenna complexes are present on thylakoids. Light striking any one of the pigment molecules is funneled to a special chlorophyll a molecu

53、le, termed a reaction-center chlorophyll, which directly participates in photosynthesis. Most photosynthetic organisms possess two types of reaction-center chlorophylls, P680 and P700, each associated with an electron acceptor molecule and an electron donor. These aggregations are known respectively

54、 as photosystem (P700) and photosystem (P680).所有的光合作用生物含有不同等級的葉綠素和一個或多個類胡蘿卜素（光合作用的輔助色素）。稱作天線復(fù)合體的色素分子群存在于類囊體中。激活色素分子的光能進(jìn)入葉綠素反應(yīng)中心，其直接參與光合作用。大部分光反應(yīng)細(xì)胞器擁有兩套反應(yīng)中心，P680和P700，每個光系統(tǒng)都含有一個電子受體和電子供體。這些集合體就是大家熟識的光合系統(tǒng)和光合系統(tǒng) 。The Light-Dependent Reaction: Converting Solar Energy into Chemical-Bond Energy光反應(yīng)：光能轉(zhuǎn)化成化學(xué)鍵

55、能The photosystems of the light-dependent reactions are responsible for the packaging of light energy in the chemical compounds ATP and NADPH. This packaging takes place through a series of oxidation reduction reactions set in motion when light strikes the P680 reaction center in photosystem . In thi

56、s initial event water molecules are cleaved, oxygen is released, and electrons are donated. These electrons are accepted first by plastoquinone and then by a series of carriers as they descend an electron transport chain. For each four electrons that pass down the chain, two ATPs are formed. The las

57、t acceptor in the chain is the P700 reaction center of photosystem . At this point incoming photons boost the energy of the electrons, and they are accepted by ferredoxin. Ferredoxin is then reoxidized, and the coenzyme NADP+ is reduced to the NADPH. The ATP generated previously and the NADPH then t

58、ake part in the light independent reactions.光反應(yīng)的光系統(tǒng)將光能轉(zhuǎn)化成化學(xué)復(fù)合物ATP和NADPH。當(dāng)光激活光系統(tǒng)的光反應(yīng)中心時，通過一系列的氧化還原反應(yīng)實(shí)現(xiàn)能量的傳遞。反應(yīng)開始時，水被分解，氧被釋放并提供電子。電子首先傳遞給質(zhì)體醌，然后通過一系列載體形成的電子傳遞鏈。每傳遞4個電子，形成2個ATP。最后一個受體存在于光反應(yīng)系統(tǒng)的反應(yīng)中心里。此處光子激活電子，電子傳遞給鐵氧還蛋白。鐵氧還蛋白再氧化，并且輔酶NADP+還原成NADPH。早期產(chǎn)生的ATP和NADPH進(jìn)入暗反應(yīng)。The production of ATP from the transport of electrons excited by light energy down an el