The pairing of homologous chromosomes at zygotene is followed, at the end of pachytene, by their separation. By now, as we have seen, each of the homo-logues is visibly double and, at one or more corresponding points along their length, two of the four chromatids present in each bivalent criss-cross over one another forming characteristic chiasmata. The origin of these chiasmata has been, indeed for some still is, one of the main subjects of controversy in genetics.
KeywordsChiasma Frequency Torsion Theory Maleic Hydrazide Strand Exchange Mitotic Recombination
Unable to display preview. Download preview PDF.