Genetic unity and biochemical diversity in genetic recombination mechanisms

Abstract

Obstacles to the unification of recombination mechanisms are: the multiplicity of ways of systematizirig and describing the telltale aberrant or exceptional recombination events, and the substantially different ways of calculating recombination and expectation, in different genetic materials and systems. All deviations consist of the type that certain subclasses of the populations exhibit greater frequency of certain recombinations than do other subclasses. It is suggested that, instead of deriving from different modes or pathways of recombination, these different observations stem from biochemically different probabilities for the localization of first and subsequent breakages, degradations, syntheses and joinings of DNA molecules. The various mutants and species studied have in general different relative activities of the endonucleases, exonucleases, polymerases and ligases accounting for these steps. Therefore, differences between the species and strains can presently be attributed to quantitatively different rates and extents of biochemical action upon essentially uniform material, DNA, by mechanisms that are virtually uniform in the different organisms.