Question

Describe how new combinations of alleles can be formed through the process of meiosis.

Answer 1

MEIOSIS:-

Meiosis occurs over two generations of cells. In meiosis I, the chromatids do not separate, which means each daughter cell receives only one copy of each chromosome, the haploid number, and each copy contains two chromatids. In meiosis II, the chromatids separate and are distributed to each resulting gamete.

Following are the methods which introduce genetic diversity during meiosis:-

1. CROSSING OVER:-

During prophase of meiosis I, the double-chromatid homologous pairs of chromosomes cross over with each other and often exchange chromosome segments. This recombination creates genetic diversity by allowing genes from each parent to intermix, resulting in chromosomes with a different genetic complement. The exchange occurs between non-sister chromatids. Because genes often interact with each other, the new combination of genes on a chromosome can lead to new traits in offspring.

2. RANDOM CHROMATID ASSORTMENT OR INDEPENDENT ASSORTMENT;-

A third source of genetic diversity occurs during meiosis II, in which the sister chromatids separate and are randomly distributed to the daughter cells, the gametes. Crossing over in meiosis I leads to non-identical chromatids in meiosis II chromosomes. During anaphase of meiosis II, the centromere joining each chromatid pair dissolves, creating two chromosomes of each type. The outcome of which chromosome will go to which gamete is random, so that each gamete has a potentially unique combination of genetic material.