Post by skyship on Jun 7, 2009 0:43:20 GMT -5
The Price of Silent Mutations
June 2009; Scientific American Magazine
by J. V. Chamary; Laurence D. Hurst
Biologists long thought they understood how genetic mutations cause disease. But recent work has revealed an important twist in the tale and uncovered surprising—even counterintuitive—ways that alterations in DNA can make people sick. The classic view assumed that what are termed "silent" mutations were inconsequential to health, because such changes in DNA would not alter the composition of the proteins encoded by genes. Proteins function in virtually every process carried out by cells, from catalyzing biochemical reactions to recognizing foreign invaders. Hence, the thinking went, if a protein's makeup ends up being correct, any small glitches in the process leading to its construction could not do a body harm.
Yet detective work occasionally traced a disorder to a silent mutation, even though researchers presumed that it could not possibly be the culprit. Similar mysteries popped up in studies of genome evolution, where patterns of changes in the DNA of various species indicated that many silent mutations were preserved over time—a sign that they were useful to the organisms possessing them. In many species, these changes seemed to help cells make proteins more efficiently, but not in people.
[Think "The Principle of Recursive Genome Function". As long as Crick's "Central Dogma" ruled (for too long, from 1953 to 2008 when the Principle was published) the DNA>RNA>PROTEIN chain was a "forward growth" - with proteins a "dead end" (from which information could "never" recurse to the DNA). For such a "forward growth" the redundancy of codons (DNA base-triplets, producing just 22 of the theoretically possible 64 different amino-acids to build proteins) simply could not matter - since because of the redundancy the "end product" was the same. With The Principle of Recursive Genome Function, for the protein-binding sites on the "non-coding" (regulatory) intronic and intergenic regions suddenly it does, indeed, matter, if the seemingly bio-identical amino-acids do or do not bind with DNA "codons" upon recursion. "Junk DNA diseases" (e.g. Marfan Syndrome) thus may be caused by "silent mutations" - looked at only after the Genome Revolution of June 14, 2007 (release of ENCODE) - Pellionisz_at_junkdna.com, June 1st, 2009]
www.junkdna.com/hologenomics_history.html#silent_mutations
got the magazine as well.
skyship