Me的私筆記

2009年諾貝爾生理學或醫學獎星期一在瑞典揭曉，共同得主是三位發現端粒和端粒酵素與人類染色體關係的美國科學家。
這三名科學家是加利福尼亞大學的伊麗莎白·布蘭科伯恩、巴爾的摩約翰霍普金斯醫學院的卡羅爾·格雷德和哈佛醫學院的傑克·紹斯塔克。

他們發現了細胞分裂時染色體是怎樣進行的完整複製，防止染色體自然脫落引發的衰老或病變。

科學家把端粒稱為「生命之鐘」，因為所有的細胞每分裂一次，端粒就縮短一點。當端粒短到不能再縮時，細胞就無法繼續分裂而死亡。

染色體的自然脫落物就是端粒酵素，它們在惡性細胞的生長中起極其重要的作用，百分之90左右的癌細胞中都有不斷增長的端粒和相當多的端粒酵素。

Since the discovery of genes, we have learned that there are portions of chromosomes that don't represent the code for anything functional (i.e. a protein). Telomeres are segments of non-coding, repeating units of DNA found at the ends of our chromosomes, but they serve a variety of different purposes, including making sure our chromosomes align properly during replication. Also, since replication of DNA inevitably introduces some degree of error to the sequence, one of the causes of gene mutation, and since these errors occur more frequently on the ends, the telomeres protect important gene sequences from becoming mutated. Telomeres shorten gradually as our cells replicate and make copy after copy of DNA. Some evidence suggests telomere shortening might be an early sign of cancer, as is indicates frequent cell reproduction. Other research shows that once the telomeres become too short, the enzyme telomerase can lengthen them again, allowing cell replication to continue. Normal cells don't have telomerase activity and control of the enzyme might be an answer to tumor suppression in cancer treatment. Telomeres also play a role in epigenetics, as they appear to be involved in the protection of histone structures, and their lengths are correlated to certain epigenetic markers.