生物专业英语教材

生物专业英语教材 生物专业英语（English For Biology students） Lesson One（学时） Inside the Living Cell: Structure and Function of Internal Cell Parts ：使学生掌握细胞的组成结构（各种细胞器以及它们在细胞中的位置）， 以及结构与功能之间的关系。各细胞器及功能相关英语词汇以及主要用法。 ：各细胞器的概念和功能，及相关英语词汇的掌握 ：专业英语词汇的记忆 ：以学生翻译为主，老师讲解相关专业知识辅助学生理解 2月23日；2月27日； 3月2日 ： 1Cytoplasm: The Dynamic, Mobile Factory 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. 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. 2Organelles: Specialized Work Units 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. 1 生物专业英语（English For Biology students） 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. 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. 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. 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. 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). 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 2 生物专业英语（English For Biology students） most biological macromolecules. They act to digest food particles and to degrade damaged cell parts. 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. 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. 4The Cytoskeleton 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. 5Cellular Movements 3 生物专业英语（English For Biology students） Although the cytoskeleton provides some stability to cells, its microtubules and filaments and their associated proteins enable cells to move by creeping or gliding. Such movements require a solid substrate to which the cell can adhere and can be guided by the geometry of the surface. Some cells also exhibit chemotaxis, the ability to move toward or away from the source of a diffusing chemical. Certain eukaryotic cells can swim freely in liquid environments, propelled by whiplike cilia or flagella. 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 is located. Movement is based on the activities of tiny dynein side arms that extend from one of the microtubules of each doublet. Nutrients, proteins, and other materials within most plant cells are moved about via cytoplasmic streaming. The process occurs as myosin proteins attached to organelles push against microfilaments arrayed throughout the cell. Microfilaments and microtubules are responsible for almost all major cytoplasmic movements. During cell division, microtubules of the spindle assembled from tubutin subunits near organelles called centrioles move the chromosomes. 4 生物专业英语（English For Biology students） Glossary actin 肌动蛋白 A globular contractile protein. In muscle cells, actin interacts with another protein, myosin, to bring about contraction. 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. chemotaxis 趋化性 A locomotory movement of an organism or cell in response to, and directed by, an directional stimulus. chloroplast 叶绿体 A plastid in which photosynthesis is carried out. Chloroplasts occur in all photosynthetic organisms except photosynthetic bacteria blue-green algae. 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. cilia 纤毛 Numerous short, hairlike structures projecting from the cell surface that enable locomotion. 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 5 生物专业英语（English For Biology students） 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. 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. endoplasmic reticulum 内质网 Folded membranes and tubes throughout the eukaryotic cell that provide a large surface upon which chemical activities take place. flagella 鞭毛 (单数flagellum) Long, hairlike structures projecting from the cell surface that enable locomotion. 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. lysosome 溶酶体 A specialized organelle that holds a mixture of hydrolytic enzymes. 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. 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. 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. nucleus 细胞核，核(复数 nuclei) 6 生物专业英语（English For Biology students） 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 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 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 polysome 多核糖体 Of protein synthesis, several ribosomes all translating the same messenger RNA molecule,one after the other. ribosome 核糖体 Small structures composed of two protein and ribonucleic acid subunits involved in the assembly of proteins from amino acids. stroma 基质，子座（复数 stromata） Region within a chloroplast that has no chlorophyll. tubulin 微管蛋白 A protein that is the major constituent of microtubules. vacuole 液泡 Storage container within the cytoplasm of a cell having a surrounding membrane. 7