Chronologic evolution markers
March 11, 2002 Dov, in biologicalEvolution forum.
Present chromosomal genes associations are symbiotic evolutionary products of earlier genes; the earliest genes, celled or yet uncelled, probably having been single independent self-sustaining genes.
Is it not feasible to infer some or many of the chronological evolutionary steps in the development of genes from observations of the mechanisms of their maintenance?
Thus, in Nature Reviews Molecular Cell Biology 3,145(2002) Kai-Ming Chou and Yung-Chi Cheng shed new light on the mechanism of DNA base-excision repair (BER), which is used to remove a variety of damaged bases. The first step of BER is removal of the damaged base by a DNA glycosylase. The remaining 'abasic' site is recognized by an apurinic/apyrimidinic endonuclease (APE), which cleaves the phosphodiester bond 5' to the lesion. DNA polymerase then replaces the missing base, and the final step involves resealing of the nick by a DNA ligase.
Is it not possible that at some way back times any or all of these four steps were not yet a synchronized sequence but separate maintenance operations for one or few mono- or oligo-genes?
In a similar vein, when the question is raised if nitric oxide modulates mitochondrial energy generation and apoptosis, is it not possible that these effects of nitric oxide especially on the mitochondrion may be chronologic markers of atmospheric composition changes during an early phase of yet independent self-sustaining mitochondrion?