Question

"If two genes are on the same chromosome, the maximum possible recombination frequency between them is 50%. However, the map distance between two genes on the same chromosome can be larger than 50 m.u." Explain this statement.

Answer 1

The recombination between two genes is a random process. The two genes at a certain distance allow the recombination to occur with a certain probability. Smaller the distance, the probability is limited. When the two genes are distant, the probability of recombination may increase multiuple times and multiple events of recombination may occur.

Recombination is always resultin producing odd number of gametes. In distant genes, the probability of producing recominant or odd number gametes and parental or even number of gametes is always equal. Threfore, recombnants produced are equal to 50% and the map distance is 50 c.M and genes apart may have great distance but the recombinants produced are only 50%.