AGB 121: Principles of Animal Genetics and Population Genetics (2+1)

STRENGTH OF LINKAGE

• The strength of linkage between any two genes on a chromosome depends up on the distance between them.
• Closely located genes show strong linkage.

Chromosome theory of Linkage (Morgan & Castle)

• Genes located on the same chromosome are inherited together and are said to be linked.
• The linked genes are arranged in a linear fashion of the chromosome.
• The degree of linkage is determined by the distance between genes.
• Coupling and repulsion are two phases of the aspect of linkage.

Factors affecting linkage

• Distance: Genes widely located show weak linkage.
• Age: With increasing age, the strength of linkage decreases.
• Temperature: Increasing temperature decreases the strength of linkage.
• Radioactive rays: such as X-rays reduce the strength of linkage.