专业英语(修改版)

英语辅导

第一次作业

英译汉

1. Cell organelles are the structures within a cell. They are a bit like the organs in a human body. They each have a specific role to play and have a distinctive shape and size.

细胞器官是细胞的组成结构。他们有点像一个人类的身体里的器官。他们每个都具有特别的作用并且有独特的形状和大小。

2. Cell Membrane - The cell membrane encloses the cell contents. Its main function is to control what gets into and out of the cell.

细胞膜——细胞膜包裹着细胞内含物。它的主要功能是控制什么可以进出细胞。

3. Cytoplasm - The cytoplasm contains primarily water and protein material. This is where the other cell organelles reside, and where most of the cellular activities take place.

细胞质——细胞质主要包含水和蛋白质材料。这是其他细胞器存在的地方,也是大多数细胞活动发生的地方。

4. Nucleus - The nucleus generally contains the genetic material for the cell. Because it contains the DNA and

chromosomes, which affect the proteins that determine the activities of the cell, the nucleus can be considered

to be the cell's control centre. 细胞核-细胞核通常包含细胞的遗传物质。因为它包含了DNA和染色体,它们影响了决定细胞中活动的蛋白质,细胞核可以被认为

是细胞的控制中心。

5. Ribosomes - Ribosomes are where protein synthesis takes place. Some are attached to the rough endoplasmic reticulum,

and some are free in the cytoplasm.

核糖体——核糖体是发生蛋白质合成的地方。有些附着到粗面内质网上,有些游离在细胞质中。

汉译英

1. 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。

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.

2. 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。

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.

第二次作业

英译汉

1. Mitochondria - Mitochondria are large organelles where oxygen is combined with food to produce ATP (adenosine

triphosphate), the primary energy source for the cell. Mitochondria contain their own DNA, RNA and ribosomes, and

can reproduce themselves independently of the cell in which they are found.

英语辅导

线粒体——线粒体是大型的细胞器，在其内部氧气结合物质产生ATP(三磷酸腺苷), 细胞主要的能源来源。线粒体包含他们自

己的DNA,RNA和核糖体,并在细胞中发现可以独立的自我复制。

2. Endoplasmic Reticulum (ER) - The endoplasmic reticulum is a series of interconnecting flattened tubular tunnels.

There are two sorts of endoplasmic reticulum - rough ER and smooth ER. The rough ER has lots of attached ribosomes.

The smooth ER has no attached ribosomes and so looks 'smooth'. The rough ER takes in the proteins made on the ribosomes

so that they cannot escape into the cytoplasm. The smooth ER is not involved in protein synthesis, but has other

functions. 内质网(ER)-内质网是一系列相互联系的平的管状通道。有两种类型的内质网——粗糙ER和滑面ER。粗糙的ER有很多附着的

核糖体。光滑的ER没有附着的核糖体,所以看起来“光滑”。粗糙的ER让在核糖体上合成的蛋白质进入,所以它们不能脱离进

入细胞质。光滑的ER没有参与蛋白质的合成,但有其它的功能。

3. Golgi Complex - The Golgi complex is composed of small membranous sacs, and is associated with the endoplasmic

reticulum (ER). Though its function is still not entirely understood, it seems that proteins from the ER travel

to the Golgi complex, where they are transformed and packaged into sacs before being moved to their final destination.

高尔基复合体——高尔基复合体是由小的囊膜质组成,并且与内质网相联系(ER)。尽管它的功能还没有完全了解,似乎是蛋白质

由内质网转运到到高尔基复合体中,在那里它们被翻译并且在被运送到它们最后的位置之前被包装进囊泡。

4. Lysosomes - Lysosomes are membrane-bound sacs of enzymes. In a controlled and specific way, they breakdown old

or unneeded parts of the cell into small organic molecules that can be reused.

溶酶体-溶酶体是膜相互结合的含有酶的囊泡。用一种被控制的并特殊的方式,他们将旧的或无用的细胞部分分解成可以重新利

用的有机小分子。

汉译英

1. 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。

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.

2. 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。

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.

第三次作业

英译汉

1. Photosynthesis is a process used by plants and other organisms to capture the sun's energy to split off water's

hydrogen from oxygen. Hydrogen is combined with carbon dioxide (absorbed from air or water) to form glucose and

release oxygen. All living cells in turn use fuels derived from glucose and oxidize the hydrogen and carbon to release

the sun's energy and reform water and carbon dioxide in the process (cellular respiration).

英语辅导

光合作用是一个被植物体和其他有机生命体用来捕获太阳能将水中的氢与氧气分离的过程。氢与二氧化碳(从空气或水中吸收)

结合来形成葡萄糖并释放氧气。所有活细胞反过来使用由葡萄糖衍生的燃料以及氧化氢和碳来释放太阳能并同时在过程中生成

水和二氧化碳（细胞呼吸作用）。

2. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms

are called photoautotrophs, since they can create their own food. In plants and algae, photosynthesis uses carbon

dioxide and water, releasing oxygen as a waste product. Photosynthesis is vital for all aerobic life on Earth. In

addition to maintaining normal levels of oxygen in the atmosphere, photosynthesis is the source of energy for nearly

all life on earth, either directly, through primary production, or indirectly, as the ultimate source of the energy

in their food. 光合作用发生在植物、藻类和许多种细菌中,但不发生在古细菌中。能进行光合作用的生物体被称作光合自养生物,因为他们可

以生成他们自己的食物。在植物和藻类中，光合作用利用二氧化碳和水,释放氧气作为代谢产物。光合作用对地球上所有需氧的

生物至关重要。除了维持大气中氧气的正常水平,光合作用是地球上几乎所有生物的能量来源,无论是直接地,通过初级生产,或

间接地在他们的食物中作为最终能量来源。

汉译英

1. 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 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.

2. 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。

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.

第四次作业

英译汉

1. Mitosis and meiosis are similar processes in that they both result in the separation of existing cells into new

ones. They differ, however, in their specific processes as well as in their products. The reason for these differences

lies in the difference in the class of cells that each process creates. Mitosis is responsible for reproducing somatic

cells and meiosis is responsible for reproducing germ cells.

有丝分裂和减数分裂在它们都导致现有细胞分离生成新细胞的过程中是相似的。但是他们区别在他们的特定过程和产物。这些

差异的原因在于不同种类的细胞每个进程创建的不同。有丝分裂负责繁殖体细胞和减数分裂是负责繁殖生殖细胞。

英语辅导

2. In single-cell organisms, mitosis is the only form of cellular reproduction. One round of mitosis yields（产

生） two genetically identical cells. In bacteria, this process results in an entirely new, independent organism.

This is classified as asexual reproduction because it does not require sex for the creation of new organisms. In

multi-cellular organisms, like ourselves, mitosis only occurs in somatic cells, which comprise all cells in an

organism excluding germ cells. 在单细胞生物中,有丝分裂是细胞繁殖的唯一方式。一轮无丝分裂产生两个基因相同的细胞。在细菌中,这一过程的会产生一个

全新的、独立的有机体。这被归类为无性生殖,因为在新生物体的创造中不需要生殖细胞。在多细胞生物,和我们一样,有丝分裂

仅发生在体细胞,包含除微生物细胞外一个生物体内的所有细胞。

3. Cells that undergo mitosis duplicate their chromosomes, resulting in cells with two times their normal haploid

or diploid numbers (4N chromosomes). Newly-synthesized chromosomes remain closely associated with their

like-chromosome. These two identical chromosomes are called sister chromatids. Once duplicated, sister chromatids

separate such that one copy of each chromosome lines up on opposite ends of the cell. The cell then pinches in the

center until it breaks into two different cells. 进行有丝分裂的细胞复制它们的染色体,导致细胞具有两倍其正常单倍体或二倍体数目(4 N染色体)。新合成的染色体仍然与和

他们类似的染色体保持紧密的联系。这两个相同的染色体称为姐妹染色单体。复制的时候,姐妹染色单体分离导致每个染色体的

副本都排列在细胞的两极。细胞随之在中心缢裂直到分裂成两个不同的细胞。。

4. There are two major differences between mitosis and meiosis. First, meiosis involves not one, but two cell divisions.

Second, meiosis leads to the production of germ cells, which are cells that give rise to gametes. Germ cells are

different from somatic cells in a critical way. Whereas somatic cells are diploid, meaning they have two copies

of each chromosome, germ cells are haploid. The haploid nature of germ cells is vital to the process of sexual

reproduction. 有丝分裂和减数分裂有两个主要的不同点。首先,减数分裂包含不止一次分裂,而是两次细胞分裂。其次,减数分裂导致生殖细胞

的产生,也就是细胞产生配子。生殖细胞与体细胞非常不同。这在于体细胞是二倍体,这意味着他们每个染色体有两份,而生殖细

胞是单倍体。通常是单倍体的生殖细胞对有性繁殖的过程至关重要。

汉译英

1. 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。

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.

2. 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。

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;

英语辅导

those with cells containing a single set of parental chromosomes are called haploid.

第五次作业

英译汉

1. Mendel performed similar experiments focusing on several other traits like seed color and seed shape, pod color

and pod shape, and flower position and stem length. He noticed the same ratios in each case. From these experiments

Mendel formulated what is now known as Mendel's law of independent assortment. This law states that allele pairs

separate independently during the formation of gametes. Therefore, traits are transmitted to offspring independently

of one another. 孟德尔进行了类似的实验，这些实验集中在其他的一些性状上例如种子颜色和种子形状，豆荚颜色和豆荚形状，以及花开的位

置和茎的长度。他注意到在每种情况下同样的几率。从这些实验中,孟德尔制定了如今被称为孟德尔定律的独立分类。这一定律

阐明了在配子形成的过程中等位基因独立分离。因此,每一个性状都独立于其他性状地被遗传给后代。

2. The results of Mendel's experiments on dominant and recessive inheritance let to Mendel's first law: the law

of segregation. This law states that for a given trait an organism inherits one allele from each parent. Together

these alleles form the allele pair. When gametes are formed during meiosis, the two alleles become separated (halving

of chromosome number).To gain evidence for his theory Mendel performed test crosses, mating plants of unknown genotype

to plants that were homozygous recessive for the trait of interest. The ratio of dominant phenotypes (if any) in

the progeny makes clear whether the unknown genotype is heterozygous, homozygous dominant, or homozygous recessive. 结果孟德尔的实验在显性和隐性遗传让到孟德尔的第一定律:种族隔离的法律。这个定律表明,对于一个给定的特质有机体每个

人从父母那里继承一等位基因。这些等位基因的等位基因在一起形成一对。当配子形成减数分裂过程中,两个等位基因走散(染

色体数目的一半)。获得证据支持他的理论孟德尔执行测试跨越、交配植物基因型植物不明的纯为感兴趣的隐性性状。占主导地

位的比例表型(如果有的话)的后代使得清楚未知的基因型是杂合的,纯合子的主导,或纯合子的隐性。

汉译英

1. 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 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.

2. 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。

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.

英语辅导

第六次作业

英译汉

1. one-gene–one-polypeptide hypothesis The hypothesis that a large class of structural genes exists in which each

gene encodes a single polypeptide, which may function either independently or as a subunit of a more complex protein.

Originally it was thought that each gene encoded the whole of a single enzyme, but it has since been found that

some enzymes and other proteins derive from more than one polypeptide and hence from more than one gene. 一基因一多肽合成假说：假说的内容是存在于每个基因的一大类结构基因编码单个多肽,这些多肽可能单独行使功能或者作为一

个更复杂的蛋白质的亚基。最初被认为每个基因编码的整个单一的酶,但已经被发现一些酶和其他蛋白质来自多个多肽,因此也

由多个基因介导。

2. Okazaki fragments are short, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication. They are complementary to the lagging template strand, together forming short double-stranded DNA sections. Okazaki fragments are between 1,000 to 2,000 nucleotides long in E. coli and are between 100 to 200 nucleotides long in eukaryotes. On the leading strand DNA replication proceeds continuously along the DNA molecule as the parent double-stranded DNA is unwound, but on the lagging strand the new DNA is made in installments（部分）, which are later joined together by a DNA ligase（连接酶） enzyme（DNA连接酶）. This is because the enzymes that synthesise the new DNA can only work in one direction along the parent DNA molecule. 冈崎片段是短的,是在DNA复制过程中在后随链上新合成的DNA片段。它们与后随链互补,协助形成短的双链DNA单元。冈崎片段在大肠杆菌中是介于1000和2000个氨基酸长度以及在真核生物中是介于100到 200个核苷酸长度。由于亲本双链的解旋在起始链上的复制不断的产生DNA分子,但是在后随链上的新DNA是部分合成的，然后这些DNA再由DNA连接酶连接在一起。这是因为合成新DNA的酶只能在亲本DNA分子的一个方向上作用。

汉译英

1. 双因子杂合试验，两个特征是如何相互影响遗传的。试验结果产生独自分配定律，即等位基因独立遗传。特例是，不完全显性。子代的表型是父母本的中间类型。不完全显性说明了两个等位基因对表型都有影响。等位基因会继续分离。

Mendel also performed dihybrid crosses, which enabled him to consider how two traits are inherited relative to one another. This work let to the law of independent assortment, which states that the alleles of genes governing different characters are inherited independently. An apparent exception to Mendel's laws is incomplete dominance, a phenomenon in which offspring of a cross exhibit a phenotype that is intermediate between those of the parents. However, incomplete dominance reflects the fact that both alleles for the trait in question exert an effect on the phenotype. The alleles themselves remain separate.

2. 直到40年代末50年代初，研究者在寻求DNA结构过程中，确立了Chargaff 的观点和, Levene的组成理论以及其他两个线索。一个是Linus Pauling的假设，DNA可能具有螺旋结构，通过氢键连接。另一个是X-衍射图片，Franklin and Wilkins提供。

In the late 1940s and early 1950s, researchers looking for the structure of DNA drew upon Chargaff s insight, Levene's ideas on DNA components, and two other lines of evidence. One was the suggestion of Linus Pauling that DNA might have a helical structure held in place by hydrogen bonds, and the other was X-ray diffraction photos of DNA, showing a helical structure with distance between the coils, taken by Franklin and Wilkins.

英语辅导

英译汉来自书上

1.The results of Mendel's experiments on dominant and recessive inheritance let to Mendel's first law: the law of segregation.This law states that for a given trait an organism inherits one allele from each parent. Together these alleles form the allele pair. When gametes are formed during meiosis, the two alleles become separated (halving of chromosome number).To gain evidence for his theory Mendel performed test crosses, mating plants of unknown genotype to plants that were homozygous recessive for the trait of interest. The ratio of dominant phenotypes (if any) in the progeny makes clear whether the unknown genotype is heterozygous, homozygous dominant, or homozygous recessive.

分离定律，生物只遗传父母本等位基因对的一个等位基因。减数分裂期形成配子时两个等位基因分离。为验证此理论，他做了测交实验，即基因型未知的植物与纯合的隐性基因植物杂交。子代显性表型可以明确测得杂合基因或纯合基因的基因型。

汉译英

1.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。

2.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。

3.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.

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。

4.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.

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。

5.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.

英语辅导

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。

6.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。

7.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。

8.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。

9.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。

10.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。

11.Mendel also performed dihybrid crosses, which enabled him to consider how two traits are inherited relative to one another. This

英语辅导

work let to the law of independent assortment, which states that the alleles of genes governing different characters are inherited independently. An apparent exception to Mendel's laws is incomplete dominance, a phenomenon in which offspring of a cross exhibit a phenotype that is intermediate between those of the parents. However, incomplete dominance reflects the fact that both alleles for the trait in question exert an effect on the phenotype. The alleles themselves remain separate.

双因子杂合试验，两个特征是如何相互影响遗传的。试验结果产生独自分配定律，即等位基因独立遗传。特例是，不完全显性。子代的表型是父母本的中间类型。不完全显性说明了两个等位基因对表型都有影响。，等位基因会继续分离。

12.In the late 1940s and early 1950s, researchers looking for the structure of DNA drew upon Chargaff s insight, Levene's ideas on DNA components, and two other lines of evidence. One was the suggestion of Linus Pauling that DNA might have a helical structure held in place by hydrogen bonds, and the other was X-ray diffraction photos of DNA, showing a helical structure with distance between the coils, taken by Franklin and Wilkins.

直到40年代末50年代初，研究者在寻求DNA结构过程中，确立了Chargaff 的观点和, Levene的组成理论以及其他两个线索。一个是Linus Pauling的假设，DNA可能具有螺旋结构，通过氢键连接。另一个是X-衍射图片，Franklin and Wilkins提供。

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