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Until researchers like Razin came along, the basic story line on how genes get transcribed in a cell was neat and simple. DNA is the master code, residing inside the nucleus of every cell; RNA transcribes the code to build whatever proteins the cell needs. Then some of Razin’s colleagues showed that methyl groups could attach to cytosine, one of the chemical bases in DNA and RNA.
It was Razin, working with fellow biochemist Howard Cedar, who showed these attachments weren’t just brief, meaningless affairs. The methyl groups could become married permanently to the DNA, getting replicated right along with it through a hundred generations. As in any good marriage, moreover, the attachment of the methyl groups significantly altered the behavior of whichever gene they wed, inhibiting its transcription, much like a jealous spouse. It did so, Razin and Cedar showed, by tightening the thread of DNA as it wrapped around a molecular spool, called a histone, inside the nucleus. The tighter it is wrapped, the harder to produce proteins from the gene.
Consider what that means: Without a mutation to the DNA code itself, the attached methyl groups cause long-term, heritable change in gene function. Other molecules, called acetyl groups, were found to play the opposite role, unwinding DNA around the histone spool, and so making it easier for RNA to transcribe a given gene. |
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| Jonathan Jackson |
Yeah... I like films, I like movies, I like playing different characters and working with different actors and filming in different places. I like movies because it's kind of a combination of every art: it's like, it's picture, it's story, it's music, it's kind of like a clash and a collide of every art. It's really neat. |
| Sholom Aleichem |
Playing nuts is a game like any other, neither better than tops, nor worse than cards. The game is played in various ways. There are 'holes' and 'bank' and 'caps.' But every game finishes up in the same way. One boy loses, another wins. And, as always, he who wins is a clever fellow, a smart fellow, a good fellow. |