[NetBehaviour] Scientists Say They’ve Found a Code Beyond Genetics in DNA.

marc marc.garrett at furtherfield.org
Wed Jul 26 16:52:50 CEST 2006

Scientists Say They’ve Found a Code Beyond Genetics in DNA.

Researchers believe they have found a second code in DNA in addition to 
the genetic code.

The genetic code specifies all the proteins that a cell makes. The 
second code, superimposed on the first, sets the placement of the 
nucleosomes, miniature protein spools around which the DNA is looped. 
The spools both protect and control access to the DNA itself.

The discovery, if confirmed, could open new insights into the higher 
order control of the genes, like the critical but still mysterious 
process by which each type of human cell is allowed to activate the 
genes it needs but cannot access the genes used by other types of cell.

The new code is described in the current issue of Nature by Eran Segal 
of the Weizmann Institute in Israel and Jonathan Widom of Northwestern 
University in Illinois and their colleagues.

There are about 30 million nucleosomes in each human cell. So many are 
needed because the DNA strand wraps around each one only 1.65 times, in 
a twist containing 147 of its units, and the DNA molecule in a single 
chromosome can be up to 225 million units in length.

New York Times.

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