专业英语 第二章

Despite the great variety of living creatures, their component cells all have a great deal in common. There are two main kinds of cell, the simpler , such as bacteria, have a single membraneenclosed compartment, a prokaryotic原核 的 cell (from the greek希腊 for ―before nucleus‖). prokaryotic cells have no obvious structures or compartments in the cytoplasm细胞质.the jellylike 胶状 material enclosed within the plasma membrane.
Membranes are somewhat fluid structures. The endoplasmic reticulum 内 质网and Golgi bodies 高尔基体form an interconnected series of membranes, sacs and bags 囊泡（vesicles）and organelles, which provide a controlled environment for the synthesis 合成and packaging 包装of many cell products. Vesicles pinched off 脱落from the system carry the products to other parts of the cell, or fuse with 融合the plasma membrane to release their contents on the cell surface.
The organelles have further function of increasing the area of membrane in the cell. Many reactions take place on membranes. Successive连续 reactants can be arranged close together in the correct sequence, speeding up metabolic reactions.. 细胞器能进一步增加膜的单元格区域的 功能。许多反应都发生在膜上。连续反 应可以按照正确的顺序紧密排列，进而 加快代谢反应。
Membranes can control the rate of reaction by restricting 限制the rate at which reactants enter the organelle 细胞 器or cell. Potentially 潜在的harmful waste products of metabolism 代谢can be isolated from the rest of the cell in membrane bags and destroyed there if necessary 膜可以通过限制物质进入的细胞器或细 胞反应的速率来控制反应的速率。潜在 的有害的代谢产物可以通过膜的单元格 隔绝，如有必要可以将其毁坏。
所有生物都是由一个或多个小隔间或细胞组成。 细胞能够维持生命活动和自我修复,以及再生。 在当今世界，每个细胞都来源于分裂的古老细 胞。
A cell is a mass of living matter surrounded by a thin membrane (the plasma membrance)细 胞膜, composed of various lipids 脂质and protein. This membrane forms a barrier 屏 障between the living matter and its surroundings, allowing the many reactions of life to proceed 进行without interference 干扰from other chemicals in the environment. materials can pass in and out of cells through the plasma membrane, but the cell can control which substances物质 pass in each direction.
尽管有各种各样的生物,组成他们的细 胞有很多共同之处。主要有两种类型的细 胞,较简单的,如细菌,原核细胞(希腊语“核 ”)原核细胞没有明显的细胞核结构或隔间 ，质膜内的胶状物质封闭。 所有其他生物都有真核细胞(希腊语“ 真正的核”)。这些包含许多专业,面上被 称为细胞器的小隔间里,其中一个——神经 核包含着遗传物质。细胞器创建一系列细 胞内的微环境,特定序列的反应能够在最大 效率,他们在空间和时间分开不同的化学反 应
Microtubules consist of parallel rows of globular 球状proteins called tubulin.微管 蛋白 They can be disassembled 拆卸and reassembled 组装as needed. They cluster 聚集where new membrane is being organized, and form scaffolds 支架 that control the way the genetic material is partitioned 分配during cell division. Microtubules may also be involved in the movement of vesicles in the cell.
ENGLISH FOR BIOLOGY
屈维 201211440821
目录Contents
1 2
The origin of the cells
the bamolecules on the surface
The size of cell Two kinds of cells Control of metabolic reactions
细胞的一系列的生命物质都由薄膜 (细胞膜)包围,它由不同的脂质和蛋白 质组成 细胞膜构成生命物质与细胞内其他 物质间的生理屏障,许多生理反应在这 里进行而不受环境中其他化学物质的 干扰。 某些物质可以通过质膜进出细胞, 但物质运输的方向受细胞控制。
Recognition molecules on the surface 表 面识别分子of the plasma membrane allow cells to recognize each other and to sense their surroundings. They can distinguish between normal and foreign cells and substances,and can receive and respond to chemical messengers from other parts of the body.
细胞膜上的表面识别分子允许细胞间相 互识别以及感知周围环境。他们能够区 分正常的和外来细胞和物质,并能接收和 回应身体的其他部位的化学信息。
Cells vary greatly in the size ,but the average cell is invisible to the naked eye 肉眼. they are usually measured inmicrometers 微米(thousandths of a millimeter毫米).most cells are between 10 to 30 micrometers in diameter直径, a few , such as a newly fertilized bird’s egg. Some frog and fish egg and certain giant algal cells, are large enough to see with the naked eye. The size of most cells is restricted by the need to transport occurs mainly by diffusion path扩散路径,and the less efficient 效率the transport.
All other living organisms have eukaryotic 真核cells (from the greek for ―true nucleus‖).these contain a number of specialized,membrane-bounded compartments called organelles, one of which –the nucleus-contains the genetic material. The organelles create a series of microenvironments within the cell,in which certain sequences of reactions can proceed at maximum efficiency, they separate different chemical reactions in space and time
不同种的细胞大小不一,但一般情况下 细胞在肉眼下是看不见的。他们通常以微 米(毫米的千分之一)来衡量。大多数细胞 的直径在10到30微米之间 ,有一些特例， 比如鸡蛋的精子，一些青蛙和鱼的精子以 及某些巨藻细胞,足够大的用肉眼去看到。 大多数细胞的大小是由运输次数（主要由 扩散路径,和较低的运输效率）决定。