Wednesday, July 26, 2006

A Genetic Palimpsest

A palimpsest is a manuscript page, scroll, or book that has been written on, scraped off, and used again. Architects and design historians sometimes use the word to describe the accumulated iterations of a design or a site, whether in literal layers of archaeological remains, or by the figurative accumulation and reinforcement of design ideas over time.

Researchers believe they have found a second code within DNA in addition to the genetic code which specfies protein manufacture. A nucleosome is a miniature spool of protein. There are about 30 million nucleosomes in each cell in our bodies. The DNA strand in that cell wraps around each nucleosome 1.65 times, each twist containing 147 base pairs.Using comparative analysis, scientists found that they could predict most of the locations where DNA would likely bend around nucleosomes. Nucleosomes are made up of histones, a class of proteins which are the most higly conserved in evolution, meaning they change very little across species. Thus a histone in peas and one in cows differs only in 2 of its 102 component amino acids.

New analyses of proteins like histones and other mysteries of life (like whither redundant 'junk DNA') are expected to arise from this novel insight. (story via 3QD)

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