Molecular Biology of the Cell 9.4分
读书笔记 第21页

几个词汇辨析 1. Homolog: A gene related to a second gene by descent from a common ancestral DNA sequence. The term "homolog" may apply to the relationship between genes separated by speciation (ortholog), OR to the relationship betwen genes originating via genetic duplication (see paralog). 译文 同源(基因):指遗传上来自于某一共同祖先DNA序列的基因。“同源”包含两种情况,一是物种间的同源(ortholog);另一种是同一物种内由于基因复制、分离导致的同源(paralog)。 2. Ortholog: Orthologs are genes in different species that have evolved from a common ancestral gene via speciation (1). Orthologs often (but certainly not always) retain the same function(s) in the course of evolution (2). Thus, functions may be lost or gained when comparing a pair of orthologs. 译文 直系/直向/垂直同源(基因):指位于不同的物种间的,在物种形成过程中源自某一共同祖先的基因[1]。从进化的角度来看,这类基因通常具有相同的功能,但并非绝对[2]。所以,当我们比较一对直系同源基因时,可能会发现有的已经丧失了固有的功能或者进化出了新的功能。 3. Paralog: Paralogs are genes produced via gene duplication within a genome (1). Paralogs typically evolve new functions or else eventually become pseudogenes. 译文 旁系/横向/并行同源(基因):指在一个特定的基因组中由于基因复制产生的同源[1]。通常比较这些基因时,它们可能已经彼此具有了新的(不同)功能,也可能已经成为假基因了。 综上所译,homolog包括ortholog和paralog两种类型。从这里我们可以举例说明,例如人的S100A8基因与猪的S100A8基因即为orthologs。人的a球蛋白和b球蛋白基因即为paralogs。需要补充的是,人的a球蛋白和鼠的b球蛋白基因也为paralogs。 In their travels, viruses can acci- dentally pick up fragments of DNA from the genome of one host cell and ferry them into another cell. Such transfers of genetic material frequently occur in pro- caryotes, and they can also occur between eucaryotic cells of the same species.

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