神马品牌网杀一只灰鹭会被判刑吗:事关学业呀！！
来源：百度文库 编辑：神马品牌网 时间：2024/05/05 21:46:02
A telomere is a region of highly repetitive DNA at the end of a chromosome that functions as an aglet. Every time linear eukaryotic chromosomes are replicated, the DNA polymerase complex stops several hundred bases before the end; if it were not for telomeres, this would quickly result in the loss of useful genetic information. In most prokaryotes, chromosomes are circular and thus do not have ends to suffer premature replication termination. A small fraction of bacterial chromosomes (such as those in Streptomyces and Borrelia) is linear and possess telomeres, which are very different from those of the eukaryotic chromosomes in structure and functions.
In humans and many other organisms (but not all) telomeres are extended by telomerases, specialized reverse transcriptases that are involved in synthesis of telomeres in most organisms. Telomerases are very interesting DNA polymerases in that they carry an RNA template for the telomere sequence within them.
In humans, the telomere sequence is a repeating string of TTAGGG, between 3 and 20 kilobases in length. There are an additional 100-300 kilobases of telomere-associated repeats between the telomere and the rest of the chromosome. Telomere sequences vary from species to species, but are generally GC-rich.
In most multicellular eukaryotes, telomerase is only active in germ cells. There are theories that the steady shortening of telomeres with each replication in somatic (body) cells may have a role in senescence and in the prevention of cancer. This is because the telomeres act as a sort of time-delay "fuse", eventually running out after a certain number of cell divisions and resulting in the eventual loss of vital genetic information from the cell's chromosome with future divisions. These theories remain relatively controversial at this time.
In most multicellular eukaryotes, telomerase is only active in germ cells. There are theories that the steady shortening of telomeres with each replication in somatic (body) cells may have a role in senescence and in the prevention of cancer. This is because the telomeres act as a sort of time-delay "fuse", eventually running out after a certain number of cell divisions and resulting in the eventual loss of vital genetic information from the cell's chromosome with future divisions. These theories remain relatively controversial at this time.
In humans and many other organisms (but not all) telomeres are extended by telomerases, specialized reverse transcriptases that are involved in synthesis of telomeres in most organisms. Telomerases are very interesting DNA polymerases in that they carry an RNA template for the telomere sequence within them.
In humans, the telomere sequence is a repeating string of TTAGGG, between 3 and 20 kilobases in length. There are an additional 100-300 kilobases of telomere-associated repeats between the telomere and the rest of the chromosome. Telomere sequences vary from species to species, but are generally GC-rich.
In most multicellular eukaryotes, telomerase is only active in germ cells. There are theories that the steady shortening of telomeres with each replication in somatic (body) cells may have a role in senescence and in the prevention of cancer. This is because the telomeres act as a sort of time-delay "fuse", eventually running out after a certain number of cell divisions and resulting in the eventual loss of vital genetic information from the cell's chromosome with future divisions. These theories remain relatively controversial at this time.
In most multicellular eukaryotes, telomerase is only active in germ cells. There are theories that the steady shortening of telomeres with each replication in somatic (body) cells may have a role in senescence and in the prevention of cancer. This is because the telomeres act as a sort of time-delay "fuse", eventually running out after a certain number of cell divisions and resulting in the eventual loss of vital genetic information from the cell's chromosome with future divisions. These theories remain relatively controversial at this time.
生物的啊，请问您要干什么呢，是要把这个翻译一遍还是。。。
如果要翻译我睡醒之后试试看吧
端粒是一种位于染色体末端的功能如带扣的高度重复DNA。
每次线性真核染色体被复制，DNA多聚酶合成停止在末端的几百对碱基前。如果不是因为端粒的存在，这个过程会很快地导致有效基因信息的缺失。在大部分原核生物中，染色体为环状，因此并没有末端，不会出现复制结束前停止的情况。一小部分细菌的染色体（如链霉菌属和疏螺旋体属细菌的染色体）是线性的并且具有端粒，但是它们的端粒与其他的真核生物的端粒在结构和功能上有很大的区别。
在人体和其他的有机体（并非全部）中，端粒由端粒末端转移酶和反转录酶扩充。这两种酶与大多数有机体中的端粒合成有关。端粒末端转移酶是一种非常有趣的DNA多聚酶，它们带有决定端粒序列的RNA模板。
在人体内，端粒的序列是一串重复的TTAGGG，长度在3000到20000碱基之间。还有附加的100到300千碱基长端粒联合重复，在端粒和剩下的染色体之间。端粒的序列在种与种之间有不同之处，但普遍富含GC碱基。
在大多数多细胞真核生物中，端粒只在生殖细胞中有活性。有许多理论提出每次体细胞的复制的稳定的端粒缩短可能会导致衰老或在预防癌症中起到作用。这是因为端粒充当一种时间延迟的“引线”，最后在一个确定次数的细胞分裂之后用尽，并最终导致细胞中决定未来分裂的染色体的重要基因信息的丢失。目前这些理论仍旧有着争议。
终于翻译完了，自己翻译的啊。。。。。