Tuesday, June 12, 2007

Causes of Genomic Decay are Ubiquitous

Here is a modified version of a prior post whose publication led to some technical glitches.

Radiation is but one of many genomic degradation factors. It is likely the least damaging. More problematic are replication errors and damage to DNA caused by highly reactive oxygen radicals and a phenomenon known as deamination. It is important to bear in mind that all degradation factors would have been present when life first appeared on earth. There are a number of chemicals that would cause damage to nucleic acids in extra-cellular, prebiotic scenarios. But even within a protective cellular environment biochemical reactions within cells, specifically those involved in cellular respiration, cause collateral DNA damage through oxygen radicals.

Cell can't hide from the causes of genomic decay which are everywhere. It is also not helpful to use the "simpler cell" approach. "Simple" cells exist in the imagination. They are not empirical entities. Basic cellular functions like respiration and information storage cannot be dispensed with in the name of simplicity.

From a natural history perspective the question raised by genomic repair functions is: Would new genetic information, required to generate adaptive responses to degradation factors, outpace the loss of information engendered by those same factors?



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