In this article we will discuss about:- 1. Introduction to Crossing Over of Genes 2. Factors Affecting Crossing Over of Genes 3. Cytological Basis of Crossing Over 4. Molecular Mechanism Crossing Over 5. Hybrid DNA Models of Crossing Over. Contents: Introduction to Crossing Over of Genes Factors Affecting Crossing Over of Genes Cytological Basis of Crossing Over of Genes Molecular [...]
The following points highlight the four theories proposed for the mechanism of crossing over. The theories are: 1. Janssen's Classical Theory 2. Belling's Copy Choice Theory 3. Uhl's Theory 4. Darlington's Theory of Crossing Over. Theory # 1. Janssen's Classical Theory: Janssen (1909) believed that prior to the formation of chiasmata the homologous maternal and paternal chromosomes come in pair [...]
In this article we will discuss about the molecular basis of crossing over. Any molecular model of crossing over must accommodate the explanation of the following phenomena: (a) Gene conversion, (b) Post-meiotic segregation, (c) Polarized conversion and (d) Negative interference. a. Gene Conversion: It is the unequal recovery of alleles in the region of exchange during genetic recombination in cases [...]