Question

Explain independent assortment in terms of chromosome behavior; how can it be disrupted?

Answer 1

Independent assortment is one of the 'Laws of Inheritance' as proposed by Gregor Mendel, who is known as the father of genetics. It is known that two genes, present on homologous chromosomes control the expression of a character in living beings. According to this law, the two genes of a character assort or separate out independent of the factors or genes of other characters at the time of gamete formation. The genes get randomly rearranged in the offsprings producing, both, parental and new combination of characters.

This happens because the pair of homologous chromosomes separate and get distributed between the two daughter cell during meiotic division which results in the formation of two haploid cells called gametes. This is an essential feature of sexual reproduction.

During the meiotic division, there is a stage when sister chromatids of homologous chromosomes cross-over and exchange portions of their genetic material. After this exchange, the chromatids formed have a different combination of genetic material which is not exactly the same as the parent chromosome. This is why there is so much variety within the individuals of the same family.

However, there are some genes which do not follow this law. One such example is of linked-genes. The segregation of alleles or genes during gamete formation can be affected if the two genes lie very close to each other on the concerned chromosome. They do not separate during crossing over and are likely to be inherited together.