生物专业英语第三版蒋悟生编__课文翻译

Inside the Living Cell: Structure and

Function of Internal Cell Parts

Cytoplasm: The Dynamic, Mobile Factory

细胞质：动力工厂

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 plasma 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）

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-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 contain most of the various kinds of organelles, and each organelle performs a specialized function in the cell. Organelles described 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 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 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 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 proteins are usually made in association 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 lacy array of membranous sacs, tubules, and vesicles, may be either 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.

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 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 cell.

光滑内质网上无核糖体，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。

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 delivery else 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 plant cells and serve as water reservoirs and storage sites for sugars and other molecules. Vacuoles in animal cells carry out phagocytosis (the intake of particulate matter) and pinocytosis (vacuolar drinking).

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 enzymes (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 reactions in all cells. In addition, 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 evolutionary descendants of what were once free-living prokaryotes.

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，线粒体内嵴上提供了很大的表面积并分布着产ATP酶。线粒体自我复制，并且可能是自由生活的原核生物在进化中形成的后代。

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 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.

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。叶绿体的内部结构是由多层膜形成的叶绿体基粒，其中包埋在基质中的基粒称子座。

The Cytoskeleton（细胞骨架）

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 organelles. 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. Another 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 such as myosin, dynein, and kinesin interact with the cytoskeletal filaments and tubules to generate forces that cause movements.

所有的细胞都有细胞骨架，网络结构的纤丝充满了它所能触及的全部空间并且对细胞器提供支持作用。细胞骨架大部分由微丝组成，微丝主要由可收缩的肌动蛋白组成。动植物细胞的许多种类型细胞内运动与肌动蛋白有关。第二类蛋白是肌球蛋白，它与肌肉细胞的收缩有关。细胞骨架的另一个主要结构成分是微管，由球状的微管蛋白组成，象脚手架一般维持细胞的稳定形态。细胞骨架的中间丝提供了细胞质伸缩动力。机械酶，例如，肌球蛋白，动力蛋白，驱动蛋白与微丝，微管相互作用产生动力而引起细胞运动。

Cellular Movements（细胞运动

Although the cytoskeleton provides some stability稳固to cells, its microtubules

英[?maikr?u?tju:bju:l]and filaments 丝状物and their associated proteins enable cells to move by creeping 爬行or gliding 滑动. Such movements require a solid固体的substrate to which the cell can adhere

附着and can be guided by the geometry d?i??mitri]几何形状of the surface. Some cells also exhibit [iɡ?zibit]展览chemotaxis,

kem??t?ksis趋药性the ability to move toward or away from the source of a diffusing 扩散chemical.

尽管细胞骨架提供了细胞的某些稳定性，微丝，微管及相关蛋白能使细胞爬行或滑动。这种运动需要固体基质依托并通过表面几何形状的改变而运动。某些细胞具备趋药性，即趋向或逃离扩散开的化学源。Certain eukaryotic cells can swim freely in liquid environments, propelled by whiplike cilia [?sili?]纤毛or flagella英[fl??d?el?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 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基体is located. Movement is based on the activities of tiny dynein动力蛋白side arms that extend from one of the microtubules of each doublet成对的东西.

某些真核细胞能在液体液体中自由运动，由纤毛或鞭毛推动。纤毛和鞭毛具有同样的内部结构：九个双微管环形排列，纵向延伸，环中心是两个或以上微管组成。纤毛或鞭毛从细胞表面的基体出生长，双微管的动力蛋白臂从一侧延伸到另一侧而引起运动。

Nutrients, proteins, and other materials within most plant cells are moved about via cytoplasmic streaming. The process occurs as myosin

?mai?usin肌凝蛋白proteins attached to organelles 细胞器,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 chromosomes.

大部分植物细胞的营养，蛋白质和其它物质由细胞质流运输。这个过程是由于依附在细胞器上的肌球蛋白反推排列在细胞周围的微丝形成的。绝大部分细胞质运动由微丝和微管完成。在细胞分裂期间，中心粒周围的由微管蛋白亚基装配形成的纺锤体微管移向染色体。

Glossary

cytoplasm （细）胞质

The living contents of a cell bounded externally by the plasmalemma, including an aqueous ground substance (hyaloplasm, cell sap, or cell matrix) containing organelles and various inclusions but excluding the nucleus and visible vacuoles.

cytoskeleton 细胞骨架

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 cells move through their environment.

nucleus 细胞核，核(复数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, DNA

chromosome 染色体

A DNA-histone thread residing in the nucleus of 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 拟核，类核，核质体

The DNA-containing area of a prokaryote cell, analogous to the eukaryote nucleus but not membrane bounded.

nucleoli 核仁( 单数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 a cell nucleus.

ribosome 核糖体

Small structures composed of two protein and ribonucleic acid subunits involved in the assembly of proteins from amino acids.

polysome 多核糖体

Of protein synthesis, several ribosomes all translating the same messenger RNA molecule,one after the other.

endoplasmic reticulum 内质网

Folded membranes and tubes throughout the eukaryotic cell that provide a large surface upon which chemical activities take place.

Golgi complex 高尔基复合体

A stack of flattened, smooth, membranous sacs; the site of synthesis and packaging of certain molecules in eukaryotic cells.

vacuole 液泡

Storage container 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胞饮作用

The process by which a cell engulfs some molecules dissolved in water lysosome 溶酶体

A specialized organelle that holds a mixture of hydrolytic enzymes. mitochondrion 线粒体(复数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 质体

An organelle present in all plants except bacteria, blue-green algae, and fungi; it is enclosed by two membranes (the envelope) and has various functions

chloroplast 叶绿体

A plastid in which photosynthesis is carried out. Chloroplasts occur in all photosynthetic organisms except photosynthetic bacteria blue-green algae. stroma 基质，子座（复数stromata）

Region within a chloroplast that has no chlorophyll.

microfilament 微丝，纤丝

Long, fiberlike structures made of protein and found in cells, often in close association with the microtubules; provide structural support and enable movement.

actin 肌动蛋白

A globular contractile protein. In muscle cells, actin interacts 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 enable movement.

tubulin 微管蛋白

A protein that is the major constituent of microtubules.

dynein 动力蛋白，动素

A group of at least four distinct proteins found in the flagella and microtubules of eukaryotic cells and possessing ATPase activity. chemotaxis 趋化性

A locomotory movement of an organism or cell in response to, and directed by, an directional stimulus.

cilia 纤毛

Numerous short, hairlike structures projecting from the cell surface that enable locomotion.

flagella 鞭毛(单数flagellum)

Long, hairlike structures projecting from the cell surface that enable locomotion.

basal body基体

A body identical in structure to a 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.

Photosynthesis

Photosynthesis occurs only in the chlorophyllchlorophyll叶绿素-containing cells 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细胞的respiration 呼吸is highly exergonic吸收能量的and releases energy, photosynthesis光合作用requires energy and is highly endergonic.

光合作用只发生在含有叶绿素的绿色植物细胞，海藻，某些原生动物和细菌之中。总体来说，这是一个将光能转化成化学能，并将能量贮存在分子键中，从化学和动能学角度来看，它是细胞呼吸作用的对立面。细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过程。

Photosynthesis starts with CO2 and H2O as raw materials and proceeds through two sets of partial reactions. In the first set, called the light-dependent reactions, water molecules are split裂开(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-independent 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为原材料并经历两步化学反应。第一步，称光反应，水分子分解，氧分子释放，ATP和NADPH形成。此反应需要光能的存在。第二步，称暗反应，二氧化碳被还原成碳水化合物，这步反应依赖电子载体NADPH以及第一步反应产生的ATP。

Both sets of reactions take place in chloroplasts. Most of the enzymes and pigments 色素for the lightdependent reactions are embedded 深入的内含的in the thylakoid类囊体membrane膜隔膜of chloroplasts 叶绿体. The dark reactions take place in the stroma.基质

两步反应都发生在叶绿体中。光反应需要的大部分酶和色素包埋在叶绿体的类囊体膜上。暗反应发生在基质中。

How Light Energy Reaches Photosynthetic Cells（光合细胞如何吸收光能的）

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 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 reactions 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.

生物分子能捕获可见光谱中的光能。植物细胞中叶绿素在不同光波下吸收部分吸收光谱。在吸收分子中，光的作用使分子中的电子发生重排。光子的能量激活了分子的能量状态，使其从稳定态进入不稳定的激活态。

All photosynthetic organisms contain 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 molecule, 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 as photosystem Ⅰ (P700) and photosystem Ⅱ (P680).

所有的光合作用生物含有不同等级的叶绿素和一个或多个类胡萝卜素（光合作用的辅助色素）。称作天线复合体的色素分子群存在于类囊体中。激活色素分子的光能进入叶绿素反应中心，其直接参与光合作用。大部分光反应细胞器拥有两套反应中心，P680和P700，每个光系统都含有一个电子受体和电子供体。这些集合体就是大家熟识的光合系统Ⅰ和光合系统Ⅱ。

The Light-Dependent Reaction: Converting Solar Energy into

Chemical-Bond Energy

光反应：光能转化成化学键能

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 Ⅱ. In this 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 last acceptor in the chain is the P700 reaction center of photosystem Ⅰ. 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 take part in the light independent reactions.

光反应的光系统将光能转化成化学复合物ATP和NADPH。当光激活光系统Ⅱ的光反应中心时，通过一系列的氧化还原反应实现能量的传递。反应开始时，水被分解，氧被释放并提供电子。电子首先传递给质体醌，然后通过一系列载体形成的电子传递链。每传递4个电子，形成2个ATP。最后一个受体存在于光反应系统Ⅰ的反应中心里。此处光子激活电子，电子传递给铁氧还蛋白。铁氧还蛋白再氧化，并且辅酶NADP+还原成NADPH。早期产生的ATP和NADPH进入暗反应。The production of ATP from the transport of electrons excited by light energy down an electron transport chain is termed photophosphorylation. The one-way flow of electrons through photosystems II and I is called noncyclic photophosphorylation; plants also derive additional ATP through cyclic photophosphorylation, in which some electrons are shunted back through the electron transport chain between photosystems Ⅱ and Ⅰ.

由电子传递链偶连产生ATP的过程称为光合磷酸化。通过光合系统Ⅱ流经光合系统Ⅰ的电子路径称非循环式光合磷酸化；植物通过循环式光合磷酸化获得额外的ATP，一些电子在光合系统Ⅰ和Ⅱ之间的电子传递链中回流。

The Light-Independent Reactions: Building Carbohydrates

暗反应：碳水化合物的形成

In the light-independent reactions of photosynthesis, which are driven by ATP and NADPH, C02is converted to carbohydrate. The reactions are also known as the Calvin-Benson cycle. Atmospheric CO2, is fixed as it reacts with ribulose biphosphate (RuBP), a reaction that is catalyzed by the enzyme ribulose biphosphate carboxylase. The reduction Of C02 to carbohydrate (fructose diphosphate) is completed via several more steps

of the cycle. Finally, RUBP is regenerated so that the cycle may continue.

由ATP和NADPH驱动的暗反应中，二氧化碳转化成碳水化合物。即卡尔文循环。二磷酸核酮糖固定二氧化碳，由二磷酸核酮糖羧化酶催化。

Oxygen: An Inhibitor of photosynthesis（氧：光合作用的抑制因子）High levels of oxygen in plant cells can disrupt photosynthesis and can also cause photorespiration-an inefficient fun of the dark reactions in which 02 is fixed rather than C02 and no carbohydrate is produced. Reprieve from Photorespiration: The C4 Pathway

Most plants are C3plants; they experience decreased carbohydrate production under hot, dry conditions as a result of the effects of photorespiration. Among C4 plants, however, special leaf anatomy and a unique biochemical pathway enable the plant to thrive in and conditions. Thus C4 plants lessen photorespiration by carrying out photosynthesis only in cells that are insulated from high levels of CO2. They also possess a novel mechanism for carbon fixation.

大部分植物是碳3植物，在高温干旱条件下，由于光呼吸作用而使碳水化合物的合成降低。而在大多数的碳4植物中，由于叶脉的特殊构造和独特的化学路径使植物依然很茂盛。这是碳固定的一个新机制。

课后作业：第一篇阅读材料

答案：1B,2A,3A,4D,5C,6c

Glossar

light-dependent reactions 光反应-

The first stage in photosynthesis, driven by light energy. Electrons that trap the sun's energy pass the energy to high-energy carriers such as ATP or NADPH, where it is stored in chemical bonds.

light-independent reactions 暗反应

The second stage of photosynthesis, also called the Calvin-Benson cycle, which does not require light. During the six steps of the cycle, carbon is fixed and carbohydrates are formed.

chloroplast 叶绿体

A plastid in which photosynthesis is carried out. Chloroplasts occur in all photosynthetic organisms except photosynthetic bacteria and blue-green algae.

absorption spectrum 吸收光谱，吸收谱

The spectrum obtained when radiation (light, ultraviolet radiation, etc.) from a source giving a continuous spectrum is passed through a substance.

Calvin-Benson cycle 卡尔文·本森循环

Cyclic reactions that are the "synthesis" part of the

light-independent reactions of photosynthesis. In land plants, RUBP, or some other compound to which carbon has

been affixed, under goes rearrangements that lead to formation of a sugar phosphate and to regeneration of the RUBP. The cycle runs on ATP and NADPH from light-dependent reactions. carotenoid 类胡萝卜素

Light-sensitive, accessory pigments that transfer absorbed energy to chlorophylls. They absorb violet and blue

wave-lengths but transmit red, orange, and yellow. chlorophyll 叶绿素

The green substance of plants by which photosynthesis is

accomplished; it is usually localized in intracellular

organelles called chloroplasts.

cyclic photophosphorylation

环形光合磷酸化（作用）

Cyclic photophosphorylation is coupled to cyclicelectron flow, in which ATP is the only product.

C3 plant 三碳植物

A plant in which the light-independent reactions of photosynthesis start with a threecarbon compound. Most plants are C3 plants.

C4 plant 四碳植物

A plant such as corn in which the light independent reactions of photosynthesis star with a four-carbon compound. noncyclic photophosphorylation

非环形光合磷酸化作用

Noncyclic photophosphorylation is coupled to noncyclic electron flow, the electrons being used to reduce NADP+ as well as to make ATP.

photon 光子

A particle that has zero mass or charge and unit spin, the quantum of the electromagnetic field and carrier of the electromagnetic force.

photophosphorylation 光合磷酸化作用

The synthesis of ATP from phosphate and ADP during photosynthesis, using light energy.

photorespiration 光呼吸

A light-dependent type of respiration that occurs in most photosynthetic plants and differs from normal (or dark) respiration.

photosynthesis 光合作用

The synthesis of organic compounds by reduction of carbon dioxide using light energy absorbed by chorophyll. photosystem 光合系统

One of the clusters of light-trapping pigments embedded in photosynthetic membranes. Photosystem I operates during the cyclic pathway; photosystem Ⅱ operates during both the cyclic and noncyclic pathways. ribulose biphosphate(RUBP)核酮糖二磷酸

A compound with a backbone of five carbon atoms that is required for carbon fixation in the Calvin-Benson cycle of photosynthesis.

thylakoid 类囊体

One of a number of flattened fluid-filled sacs that form the photosynthetic lamellar system of chloroplasts, photosynthetic bacteria, and blue-green algae.

Cellular Reproduction: Mitosis and Meiosis

The Nucleus and Chromosomes

The cell nucleus is the main repository of genetic information. Within the nucleus are the chromosomes tightly coiled strands of DNA and clusters of associated proteins. Long stretches of the continuous DNA molecule wind around these clusters of proteins, or histones, forming beadlike complexes known as nucleosomes. More coiling and supercoiling produces a dense chromosome structure. Each long strand of DNA combines with histones and nonhistone proteins to make up the substance chromatin.

细胞核是贮藏遗传信息的主要场所。DNA盘绕成螺旋线以及相关的成簇蛋白质。DNA螺旋线缠绕成簇的组蛋白形成珠链状的核小体。这些螺旋和超螺旋形成致密的染色体组结构。每个长链DNA与组蛋白和非组蛋白一起构成染色质物质。

A pictorial display of an organism's chromosomes in the coiled, condensed state is known as a karyotype. Karyotype reveal that in most cells all but sex chromosomes are present as two copies, referred to as homologous pairs. Non-sex chromosomes are called autosomes. Organisms whose cells contain two sets of parental chromosomes are called diploid; those with cells containing a single set of parental chromosomes are called haploid.

染色体致密的超螺旋状态我们称染色体组。除了性染色体外，大多数细胞的染色体组成对出现，称同源染色体对。非性染色体称常染色体。生物细胞含有两套父母本染色体的称二倍体；含有单套染色体的称单倍体。

The Cell Cycle

The cell cycle is a regular sequence in which the cell grows, prepares for division, and divides to form two daughter cells, each of which then repeats the cycle. Such cycling in effect makes single-celled organisms immortal. Many cells in multicellular organisms, including animal muscle and nerve cells, either slow the cycle or break out of it altogether.

在细胞生长过程中，细胞循环遵循特定程序，分裂准备，分裂成2个子细胞，子细胞再循环。此循环使得单细胞永生。多细胞生物中的许多细胞，包括动物肌肉和神经细胞，要么降低循环速度，要么同时分裂。

The normal cell cycle consists of four phases. The first three include G1, the period of normal metabolism; S phase, during which normal synthesis of biological molecules continues, DNA is replicated,

and histones are synthesized; and G2, a brief period of metabolism and additional growth. Together the G1, S, and G2phases are called interphase. The fourth phase of the cell cycle is M phase, the period of mitosis, during which the replicated chromosomes condense and move and the cell divides. It is believed that properties of the cell cytoplasm control the cell cycle, along with external stimulators and inhibitors such as chalones.

正常细胞循环由4个时期组成。头三期包括G1,正常新陈代谢；S期,正常新陈代谢同时，DNA复制，组蛋白合成；G2 期，短期的新陈代谢和少许生长。G1, S, 和G2称分裂间期。最后是M期，有丝分裂期，复制的染色体组浓缩，移动并细胞分裂。据称是染色质控制了细胞循环，伴随外部激活因子和抑制因子如抑素。

Mitosis: Partitioning the Hereditary Material

Biologists divide the mitotic cycle into four phases. At the beginning of prophase 前期the chromosomes each consist of two highly condensed chromatids attached to each other at a centromere. As prophase ends and metaphase 中期begins, the condensed 浓缩的chromosomes become associated with the spindle 纺锤体. Eventually the chromosomes become arranged in a plane (called the metaphase plate) at a right angle to the spindle fibers. Next, during anaphase 后期, the two sister chromatids of each chromosome split, and one from each pair is drawn toward each pole of the cell. During telophase 末期nuclear envelopes 包膜begin to form around each set of chromosomes, and division of the cytoplasm takes place.

生物学家将有丝分裂划分为4个阶段。分裂前期，高度浓缩的两个染色单体通过着丝粒连接在一起。在分裂前期后期和分裂中期前期，浓缩的染色体与纺锤体相连，最后以正确的角度排列在赤道板上。在分裂后期，两个姊妹单体分离，分别拽向细胞两极。在分裂末期，在每套染色体周围形成核膜，细胞质发生分裂。

As mitosis proceeds, the spindle microtubules play a crucial role in ensuring that both paired and separated chromatids 染色单体move in the right directions at the proper times. Each half of the spindle forms as microtubules extend from each pole of a dividing cell to the region of the metaphase plate. During prophase, other microtubules, the centromeric 着丝粒fibers, extend outward from the spindle poles to structures on the chromosomes called kinetochores着丝粒. During

anaphase the fibers begin to shorten, and the chromatids begin to move apart.

在有丝分裂过程中，是纺锤体微管确保了染色单体在适当时间以正确方向进行分离。纺锤体微管由两极向赤道板延伸。在分裂前期，其它微管，着丝粒纤维延伸到染色体的动粒。在分裂后期，纤维开始变短，染色单体分离。

The spindle forms differently in plant and animal cells. In animals it is associated with centriole 中心粒, while in plant and fungal 真菌cells spindle formation is associated with reions called microtubule organizing centers.

植物和动物细胞形成的纺锤体不同。动物细胞与中心粒相连，而在植物和真菌细胞中，纺锤体与微管组织中心的离子相连。Cytokinesis: Partitioning the Cytoplasm

胞质分裂：细胞质分离

The division of the cell cytoplasm at the end of mitosis is called cytokinesis 细胞浆移动. In animal cells it takes place as a ring of actin filaments contracts使缩短合同契约around the cell equator赤道, pinching收聚the cell in two. In plant cells, which are bounded 有限制的by a cell wall, cytokinesis involves the building of a new cell plate across the dividing cell at its equator. Cell wall material is then deposited 存放堆积in the region of the cell plate.

在动物细胞中，环形肌动蛋白丝延赤道板收缩而使细胞一分为二。在植物细胞中，在赤道板形成新的细胞板。

Meiosis: The Basis of Sexual Reproduction

Meiosis 减数is a special form of cell division that takes place in the reproductive 生殖organs that produce sex cells. Like mitosis, it takes place after DNA replication has occurred and involves two sequential 连续的nuclear divisions (meiosis I and meiosis Ⅱ). These divisions result in four daughter cells, each with half the number of chromosomes of the parent cell. The phenomenon of crossing over during meiosis results in exchanges of genetic information between chromosomes. Hence因此, the homologous 同源的chromosomes distributed 分布to different progeny 后裔cells are not identical同样的.

减数分裂是性细胞分裂的特殊形式。如有丝分裂，它也是发生在DNA复制后并有连续的两个核分裂。产生4个子细胞，分别含有亲本一半的染色体数。

As in mitosis two chromatids exist for each chromosome at the beginning of prophase 1. During this phase the homologous 同源chromosomes undergo 经历sy-napsis 联会, or pairing, which is brought about by a bridging structure of proteins and RNA called the synaptonemal 联会丝的complex. The homologous pairs stay together when they align 排列on the metaphase 中plate. Unlike the anaphase of mitosis, however, during anaphase I the two chromatids of each chromosome stay joined at the centromere 着丝点and move together to one of the two poles of the cell. It is this event that results in the halving 减半的of the chromosome number in the four daughter cells that result from meiosis.

正如在有丝分裂中一样，两个同源染色单体通过蛋白质和RNA桥配对形成联会复合体。与有丝分裂不同的是，每组染色体的两个染色单体连接在着丝点上并一起移向细胞两极的一级。由此而导致4个子细胞染色体数减半。

During telophase末期I nuclear envelopes enclose the chromosomes in nuclei, and in most species cytokinesis 细胞浆流动(the first nuclear division) follows. The second nuclear division begins with metaphase Ⅱ, in which the chromosomes in each daughter cell again align 排列on a metaphase plate. The centromeres着丝粒finally divide, and each sister chromatid moves to one of the poles of the spindle. The next phase is telophase , followed again by cytokinesis. The result of the entire process is four haploid cells in which parental chromosomes are randomly distributed.

第二次核分裂开始于分裂中期，子细胞中染色体重新排列在赤道板上。着丝粒最终分离，每个姊妹染色单体分向两极。接着胞质分裂。产生4个单倍体，父母染色体随机分配。

Asexual Versus Sexual Reproduction

Mitosis and meiosis, respectively分别, make simple cell division and sexual reproduction possible. Each means of passing on hereditary 遗传information has advantages. In asexual 无性的reproduction the parent organism生物体gives rise to offspring 后代that are genetic clones of the parent. The advantages of this type of reproduction are that it preserves the parent's successful genetic complement 遗传互补,

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管理原则 也许在那些关于管理者这门学科的书中有许多关于管理的定义。许多定义是相对扼要和简单化的。一位早期的学者将它定义为“清楚地知道你想让人们去做什么，然后看着他们以最好最廉价的方式去完成它”。管理实际上是一个非常复杂的过程——远远比那些定义让我们知道的要复杂得多。因此，我们要建立一种管理的定义，从而能更好地了解这过程的实质。 管理是在一定的环境条件下通过对人员技术和资金等资源的利用和协调去设立和完成某一个组织目标的过程。这个过程有若干个核心包括计划和决策，组织，人员，领导，管理和控制。所有从事于这些工作的负责人在更大或更小的程度上都依赖于他们所承担的特殊的责任。当谈论管理的定义时，我们不应该忽略管理的原则。 管理的最基本原则在文明诞生时就存在了。当人们第一次开始群居生活和首次提高他们的生活质量时它就存在了。2500年前，巴比伦国王尼布甲尼撒二世决定把他的沙漠王国变成绿洲去取悦他的妻子。在公元前6世纪，尼布甲尼撒二世耗尽了国家财政部的金钱，雇佣劳动者和技术人员利用有限的资源建造一个宫殿，建造了完善的管网系统，把当地河流的水输送到皇宫里。当工程完成后，他在平台上种植漂亮稀有的花草树木。巴比伦的空中花园改变了这座城市。 尼布甲尼撒二世制定了一个目标。他要把沙漠中的主要城市变成绿洲。他利用和协调人员，技术和金钱去完成这一目标。他从王室金库中获得的资金去雇佣民工和技师并从附近地区购买材料。他在这种只能提供原始水管装置，建筑技术以及只能从茫茫沙漠中取得有限的材料的环境下完成了目标。最终，每个人在这个工程商所付出的努力创造了世界七大奇观之一。 2500年前，人们完成某项巨大的任务所运用的管理过程与如今运用的基本原理相似，管理者在执行这个过程是将它分成了5个部分。 这篇文章的主旨在于表达有关管理过程的一些观点和如何将它运用到我们所面临的不同的情况中去。你们所要学习的管理原则是指指导管理者的宗旨，原则或者是组织规范。他们会提供一个行动框架，为了有效的使用他们，一个人必须培养和使用技能的决策。理智决策是识别某个问题或机会，找到可行的方法去处理它并选择最好的方法的过程。因此，决策是最重要的管理活动。管理者必须决定去实施管理的每个功能以及每种情况所需要采取的相应的原则。 在这一点上，我们对于管理必须有两点最基本的理解。首先，在特定的环境下运用各种资源设立完成目标。第二，为了确保组织的成功，组织者必须满足他的技术要求，行政要求和责任制度。尽管这听起来很简单，但这两个原则却经过了几个世纪的发展才形成的。之后将要提到的所有原则都是随着时间的推移从各种来源中汲取的。一些原则来源于各人的直觉，然而其他的则反映了组织中那些成功企业家，著名商业巨子或者是富有创新精神的工作者的经验。直到十九世纪，直觉和经验仍是管理原则的基本来源 尽管本能和直觉曾经是商业管理的基础，但现在创业者创立新的企业经常以他们的直觉进行管理。在十九世纪70年代至80年代的电脑产业中，对技术很精通，但对管理知之甚少的企业家成立了数以百计的硬件和软件公司，一些存活下来，更多的则不是。许多公司开始发展得好是得益于创

高分子材料工程专业英语翻译(最新修正稿)

UNIT 1 What Are Polymers? 第一单元什么是高聚物？ 什么是高聚物？首先，他们是络合物和大分子，而且不同于低分子化合物，譬如说普通的盐。与低分子化合物不同的是，普通盐的分子量仅仅是58.5，而高聚物的分子量高于105，甚至大于106。这些大分子或“高分子”由许多小分子组成。小分子相互结合形成大分子，大分子能够是一种或多种化合物。举例说明，想象一组大小相同并由相同的材料制成的环。当这些环相互连接起来，可以把形成的链看成是具有同种（分子量）化合物组成的高聚物。另一方面，独立的环可以大小不同、材料不同，相连接后形成具有不同(分子量)化合物组成的聚合物。 许多单元相连接给予了聚合物一个名称，poly意味着“多、聚、重复”，mer意味着“链节、基体”（希腊语中）。例如：称为丁二烯的气态化合物，分子量为54，化合将近4000次，得到分子量大约为200000被称作聚丁二烯（合成橡胶）的高聚物。形成高聚物的低分子化合物称为单体。下面简单地描述一下形成过程： 丁二烯＋丁二烯＋…＋丁二烯——→聚丁二烯 （4000次） 因而能够看到分子量仅为54的小分子物质（单体）如何逐渐形成分子量为200000的大分子（高聚物）。实质上，正是由于聚合物的巨大的分子尺寸才使其性能不同于像苯这样的一般化合物(的性能)。1例如，固态苯，在5.5℃熔融成液态苯，进一步加热，煮沸成气态苯。与这类简单化合物明确的行为相比，像聚乙烯这样的聚合物不能在某一特定的温度快速地熔融成纯净的液体。而聚合物变得越来越软，最终，变成十分粘稠的聚合物熔融体。将这种热而粘稠的聚合物熔融体进一步加热，不会转变成各种气体，但它不再是聚乙烯（如图1.1）。 固态苯——→液态苯——→气态苯 加热，5.5℃加热，80℃ 固体聚乙烯——→熔化的聚乙烯——→各种分解产物-但不是聚乙烯 加热加热 图1.1 低分子量化合物（苯）和聚合物（聚乙烯）受热后的不同行为发现另一种不同的聚合物行为和低分子量化合物行为是关于溶解过程。例如，让我们研究一下，将氯化钠慢慢地添加到固定量的水中。盐，代表一种低分子量化合物，在水中达到点（叫饱和点）溶解，但，此后，进一步添加盐不进入溶液中却沉到底部而保持原有的固体状态。饱和盐溶液的粘度与水的粘度不是十分不同，但是，如果我们用聚合物替代，譬如说，将聚乙烯醇添加到固定量的水中，聚合物不是马上进入到溶液中。聚乙烯醇颗粒首先吸水溶胀，发生形变，经过很长的时间以后，（聚乙烯醇分子）进入到溶液中。2同样地，我们可以将大量的聚合物加入到同样量的水中，不存在饱和点。将越来越多的聚合物加入水中，认为聚合物溶解的时间明显地增加，最终呈现柔软像面团一样粘稠的混合物。另一个特点是，在水中聚乙烯醇不会像过量的氯化钠在饱和盐溶液中那样能保持其初始的粉末状态。3总之，我们可以讲（1）聚乙烯醇的溶解需要很长时间，（2）不存在饱和点，（3）粘度的增加是典 型聚合物溶于溶液中的特性，这些特性主要归因于聚合物大分子的尺寸。 如图1.2说明了低分子量化合物和聚合物的溶解行为。 氯化钠晶体加入到水中→晶体进入到溶液中.溶液的粘度不是十分不同于充分搅拌 水的粘度→形成饱和溶液.剩余的晶体维持不溶解状态.加入更多的晶体并搅拌氯化钠的溶 解 聚乙烯醇碎片加入到水中→碎片开始溶胀→碎片慢慢地进入到溶液中允许维持现状 充分搅拌→形成粘稠的聚合物溶液.溶液粘度十分高于水的粘度继续搅拌聚合物的溶解

生物专业英语翻译+蒋悟生+第3版

Lesson One(4 学时) Inside the Living Cell: Structure and Function of Internal Cell Parts : The Dynamic, Mobile Factory 细胞质：动力工厂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 plasma 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。 2．The Nucleus: Information Central (细胞核：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-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。 : Specialized Work Units (细胞器：特殊的功能单位) All eukaryotic cells contain most of the various kinds of organelles, and each organelle performs a specialized function in the cell. Organelles described in this section include ribosomes, the endoplasmic reticulum, the Golgi complex, vacuoles, lysosomes, mitochondria, and the plastids of 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 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 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 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 proteins are usually made in association 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(其数量表明了核糖体是细胞过程中将氨基酸组装成蛋白质输出或供细胞所用的场所) 。一个完整的核糖体由一个大亚基和一个小亚基组成。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 lacy array of membranous sacs, tubules, and vesicles, may be either 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. 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核膜。 SER lacks 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 cell. 光滑内质网上无核糖体，主要作用是脂肪和类固醇的合成以及细胞内有毒亚物质的氧化。这两种内质网在细胞中作为分隔，使特定产品分隔开，随后将他们转移到细胞内外特定的部分或细胞外。 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 delivery else 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 plant cells and serve as water reservoirs and storage sites for sugars and other molecules. Vacuoles in animal cells carry out phagocytosis (the intake of particulate matter) and pinocytosis (vacuolar drinking). 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 enzymes (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 reactions in all cells. In addition, 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 evolutionary descendants of what were once free-living prokaryotes.

公共管理学专业英语词汇整理

公共管理学专业英语词汇 目标mission/ objective 内部环境internal environment 外部环境external environment 集体目标group objective 计划planning 组织organizing 人事staffing 领导leading 控制controlling 步骤process 原理principle 方法technique 经理manager 总经理general manager 行政人员administrator 主管人员supervisor 企业enterprise 商业business 产业industry 公司company 效果effectiveness 效率efficiency 企业家entrepreneur 权利power 职权authority 职责responsibility 科学管理scientific management 现代经营管理modern operational management 行为科学behavior science 生产率productivity 激励motivate 动机motive 法律law 法规regulation 经济体系economic system 管理职能managerial function 产品product 服务service 利润profit 满意satisfaction 归属affiliation 尊敬esteem 自我实现self-actualization 人力投入human input 盈余surplus 收入income 成本cost 资本货物capital goods 机器machinery 设备equipment 建筑building 存货inventory 经验法the empirical approach 人际行为法the interpersonal behavior approach 集体行为法the group behavior approach 协作社会系统法the cooperative social systems approach 社会技术系统法the social-technical systems approach 决策理论法the decision theory

计算机专业英语课文翻译部分(第四版)

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