In this article we will discuss about:- 1. Types of Chromosome Pairing 2. Factors Affecting Chromosome Pairing 3. Significance 4. Molecular Basis. Types of Chromosome Pairing: Chromosome pairing may be divided into three main types, viz., primary pairing, secondary association and non-homologous association, which may be further classified (Fig. 11.1). Primary Pairing: Primary pairing is observed at interphase, mitosis [...]
The following points highlight the fourteen main factors affecting crossing over and chiasma formation. The factors are: 1. Temperature 2. Age 3. Water Content 4. Sex 5. Nutritional Effects 6. Chemicals 7. Radiations 8. Shift in Population 9. Variation within the Organism 10. Chromosome Structure 11. Interference 12. Heterochromatin 13. Centromere 14. Genetic Effects. Crossing Over and Chiasma Formation: Factor [...]
The below mentioned article provides a short note on mitotic crossing over. Crossing over not only occurs during meiosis but also during mitosis. In individuals heterozygous for a gene producing a visible phenotype, somatic crossing over leads to the production of "twin spots" of dominant and recessive phenotypes. Mitotic crossing over was first discovered in Drosophila by Stern in 1936, [...]