Question

Write an explanatory note on: Linkage.

Hint:

Linked genes ride the same chromosome; distance between them decides how often crossing over splits them apart.

Answer 1

Step 1: Understanding the Concept:
Mendel's law of independent assortment assumes different genes sort into gametes independently of each other, but this only holds cleanly for genes on different chromosomes. Genes sitting on the same chromosome behave differently.

Step 2: Define linkage.
Linkage is the tendency of two or more genes located on the same chromosome to be inherited together, as a group, rather than assorting independently into gametes.

Step 3: Explain what decides how strong the linkage is.
The strength of linkage depends on the physical distance between the genes on the chromosome: genes positioned close together are inherited together more often (strong linkage, since crossing over rarely separates them), while genes positioned far apart on the same chromosome show weaker linkage (since crossing over between them happens more often).

Final Answer:
Linkage is the joint inheritance of genes carried on the same chromosome, and its strength depends on how close together those genes lie, with closer genes showing stronger linkage.