Tuesday, July 25, 2006

ID - nucleosomes and DNA control

Another example of icomprehensibly baroque and bizarre "design":
Scientists Say They’ve Found a Code Beyond Genetics in DNA - New York Times

... Having the sequence of units in DNA determine the placement of nucleosomes would explain a puzzling feature of transcription factors, the proteins that activate genes. The transcription factors recognize short sequences of DNA, about six to eight units in length, which lie just in front of the gene to be transcribed.

But these short sequences occur so often in the DNA that the transcription factors, it seemed, must often bind to the wrong ones. Dr. Segal, a computational biologist, believes that the wrong sites are in fact inaccessible because they lie in the part of the DNA wrapped around a nucleosome. The transcription factors can only see sites in the naked DNA that lies between two nucleosomes.
It's described a kind of statistical code, not directly deterministic, but on average the right places get bound. I suspect it's another variant of meaning being embedded in topology as well as sequence. Only a madman would design such a bizarre system of encoding information, yet it is incomprehensibly robust ...

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