Biochemistry - The Chemical Reactions of Living Cells, Volume 3 - D. Metzler 1980

Biochemical Genetics and the Synthesis of Nucleic Acids and Proteins
Recombination, Integration, and Excision
Nonreciprocal Recombination

Whatever recombination mechanism is proposed, it must always account for The phenomenon of Gene Conversion, or nonreciprocal recombination [220]. This phenomenon was first discovered through The Study of fungal genetics, which allows for the individual analysis of each of the four haploid products of Meiosis (tetrad analysis, Chapter 1, Section D, 2). Occasionally, instead of the standard 2:2 Mendelian segregation ratio for alleles at a heterozygous locus in the progeny, a 3:1 ratio was observed. This indicates that one of the recombinant Chromosomes has reverted to the parental type. The underlying mechanism of this phenomenon may be related to base mismatch within heteroduplex regions. Most commonly, at the site of a mutation, one strand of the heteroduplex contains a base unable to form a proper complementary pair with the base on the opposite strand. Furthermore, one of the strands may contain an extra base that forms a protruding loop out of the heteroduplex. Because Cells possess repair systems capable of recognizing and correcting such defects, one of the strands in the heteroduplex region may well be modified to restore correct pairing, thereby resulting in the observed gene conversion.



Last update: 06/08/2026

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