Question

Does meiosis cause the separation of homologous chromosomes?

Answer 1

Hint: Meiosis is a double division of diploid cells, in which the chromosome number is reduced to half and forms four haploid cells. Since meiosis reduces the number of chromosomes to half, it is popularly called reduction division. Reduction division is also the name of the first division of meiosis. Meiosis consists of two successive divisions, meiosis I and meiosis II.

Complete answer:
Meiosis I: It is the first division of meiosis where a diploid cell divides into two daughters, each having half the number of chromosomes. The daughter cells are therefore haploid but with 2n DNA content. Meiosis I is known as the reduction division due to reduction in the number of chromosomes. It is also called heterotypic division because it changes the pattern or type of cell from diploid to haploid form.
Meiosis II: It is the second division of meiosis in which replicated or double-stranded chromosomes split and single stranded chromosomes pass into daughter cells. Meiosis II maintains the haploid number of chromosomes obtained after meiosis I while changing 2n DNA content to In DNA content of the cells. It is called homotypic (Gk. homos-same, typos-pattern) division or equational division because of maintaining the same number of chromosomes.
Meiosis I has two steps, karyokinesis I and cytokinesis I. Karyokinesis I is distinguishable into four stages- prophase I, metaphase I, anaphase I and telophase I.
In Anaphase I of meiosis I, the homologous chromosomes separate and pass towards the different poles of the spindle, creating two haploid sets of chromosomes. The separation of homologous chromosomes through breakdown of their connecting chiasmata is called disjunction.

Note:
After disjunction, the separated chromosomes are called univalents. They are called dyads because each univalent is replicated and made of two chromosomes. The chromatid ends are also divergent or bent away from each other. Since the paternal and maternal chromosomes are randomly arranged over the double metaphasic plate, the two chromosomes of each homologous pair are independent of chromosomes of other pairs. This forms the basis of Mendel’s law of independent assortment and one of the major reasons for genetic variability.