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
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