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SSS 2008-08-07

时间:2010-05-14 06:12来源:互联网 提供网友:木渐浅。   字体: [ ]
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This is Scientific American's 60-Second Science. I'm Steve Mirsky, got a minute?

Neandertals were our closest relatives. And now we know a lot more about them. Because researchers have for the first time sequenced a complete Neandertal genome—that of their mitochondrial DNA1. The study appears in the August 8th issue of the journal Cell. We all have a large genome in our cell nuclei2. Then there’s a separate genome only in mitochondria, those organelles forever immortalized in textbooks as the powerhouse of the cell. The Neandertal DNA sequence falls outside the variation range found in humans today. It also confirms that the last common ancestor of us and Neandertals lived some time between 800,000 and 520,000 years ago. The new info shows that a disproportionate number of Neandertal sequence differences change the amino acid sequences in proteins. One explanation would be that Neandertals had a smaller population size. Which would give natural selection fewer options to choose from. So, did Neandertals mix with our direct ancestors? The sequence finds no evidence for such mixing. But we’ll have to wait for a full nuclear genome sequence to be sure.

Thanks for the minute, for Scientific American's 60-Second Science, I’m Steve Mirsky.


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1 DNA 4u3z1l     
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句:
  • DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
2 nuclei tHCxF     
n.核
参考例句:
  • To free electrons, something has to make them whirl fast enough to break away from their nuclei. 为了释放电子,必须使电子高速旋转而足以摆脱原子核的束缚。
  • Energy is released by the fission of atomic nuclei. 能量是由原子核分裂释放出来的。
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TAG标签:   SSS  nuclei
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