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维基百科词条Ploidy(有空翻一下)  

2010-06-05 17:32:17|  分类: 默认分类 |  标签: |举报 |字号 订阅

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Ploidy is the number of complete sets of chromosomes in a biological cell. In humans, the somatic cells that compose the body are diploid (containing two complete sets of chromosomes, one set derived from each parent), but sex cells (sperm and egg) are haploid (one set of chromosomes). In contrast, tetraploidy (four sets of chromosomes) is a type of polyploidy and is common in plants, and not uncommon in amphibians, reptiles, and various species of insects.

染色体倍性是指细胞中完整染色体组的数目。在人类中,体细胞是二倍体(含有两个染色体组,其中每一个染色体组分别来自双亲中的一方),但是性细胞(精子或卵细胞)则是单倍体(一个染色体组)。与之相对,四倍体(含有四个染色体组)是一种多倍体,在植物中较为常见,也存在于两栖类、爬行类和许多昆虫中。

The number of chromosomes in a single non-homologous set is called the monoploid number (x). The haploid number (n) is the number of chromosomes in a gamete of an individual. Both of these numbers apply to every cell of a given organism. For humans, x = n = 23; a diploid human cell contains 46 chromosomes: 2 complete haploid sets, or 23 homologous chromosome pairs. In some species (especially plants), x and n differ, for example common wheat is an allopolyploid with six sets of chromosomes (2n=6x), two sets coming originally from each of three different species, with six sets of chromosomes in most cells and three sets of chromosomes in the gametes.

没有同源关系的一组染色体的数目被称作一倍体染色体数(用x表示——译注:应该有更专业的词汇,暂未找到)。单倍体染色体数(用n表示——译注:应该有更专业的词汇,暂未找到)是指个体配子中所含的染色体数目。x和n可适用于所有给定生物体的细胞。以人为例,x=n=23;人类的二倍体细胞含有46条染色体:2个完整的染色体组,或者可以说含有23对同源染色体。在一些物种中(特别是在植物中),x和n并不相同,比如普通小麦是含有6个染色体组的异源多倍体(2n=6x),其中每两组染色体分别来自三个不同的物种,体细胞中含有6个染色体组而配子中含有3个染色体组。

The Australian bulldog ant, Myrmecia pilosula, a haplodiploid species, has n = 1, the lowest theoretically possible [1].

一种澳大利亚蚂蚁(M. pilosula),可以产生单倍体,其配子中n=1(译注:即性细胞中只含有一条染色体),是理论上染色体数目最少的生物。

Euploidy is the state of a cell or organism having an integral multiple of the monoploid number, possibly excluding the sex-determining chromosomes. For example, a human cell has 46 chromosomes, which is an integer multiple of the monoploid number, 23. A human with abnormal, but integral, multiples of this full set (e.g. 69 chromosomes) would also be considered as euploid. Aneuploidy is the state of not having euploidy. In humans, examples include having a single extra chromosome (such as Down syndrome), or missing a chromosome (such as Turner syndrome). Aneuploid karyotypes are given names with the suffix -somy (rather than -ploidy, used for euploid karyotypes), such as trisomy and monosomy.

整倍体是指细胞中含有一组或多组一倍体染色体,包括性染色体。例如,正常人含有46条染色体,外加了一组一倍体染色体(译注:即含有两个一倍体染色体)。一个异常的人,如果再附加一个完整的染色体组(含有69条染色体)都可以视作为整倍体。非整倍体和整倍体不同。在人类中,如果附加一条额外的染色体(比如唐氏综合征——译注:多了一条23号染色体),或者是缺失了一条染色体(比如特纳氏综合征——译注:缺少了X染色体)。非整倍体核型在命名时使用-somy作为后缀(不是用后缀-ploidy,-ploidy用作整倍体的后缀),比如trisomy(三体——译注:唐氏综合征患者即为三体)和monosomy(单体——译注:特纳氏综合征患者即为单体)

term is well established in this original sense[5][6], but it has also been used for doubled monoploids or doubled haploids, which are homozygous and used for genetic research[7].

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