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Please only answer if you are going to be very detailed and answer all of them. I want to learn and im lost. Thank you very much.

Mitosis and meiosis are both processes of cell division involved in reproduction. The following questions compare and contrast meiosis with mitosis. a) The ploidy of daughter cells as a result of meiosis is different than that of the parental cell. Briefly explain what this statement means. Specify what phase during meiosis this change occurs. [2 pts] b) Just as in mitosis, cohesin is an important protein that keeps chromatids together during meiosis and is similarly targeted by separase as well. In the context of meiosis, however, there are multiple variants of cohesin with different quaternary structures. Why do you think this is necessary? [2 pts] c) Homologous recombination is a unique feature of meiosis whose purpose is to increase genetic diversity during reproduction. What does the process of homologous recombination entail, and how does this process achieve the purpose of increasing diversity? When does homologous recombination occur? [2 pts] d) Define independent assortment within the framework of meiosis. What impact does homologous recombination have on the principle of independent assortment? [3 pts]

Explanation / Answer

a) ploidy means the number of sets of the entire genome present in one cell of an organism. During meiosis, the number of chromosomes in the cell is reduced to half. In other words, the parental cell having 2 sets of of the genome (ploidy = diploid = 2n) gives rise to daughter cells containing only 1 set of the genome (ploidy = haploid = n ).

This occurs during anaphase - I.

b) this is necessary as meiosis I is a reductional division wherein the cohesins are not cleaved while during meiosis II, equational division occurs and here the cohesins need to be cleaved. Hence different variants of cohesion subunits make this possible.

c) homologous recombination involves the formation of holiday junction followed by exchange of DNA region between homologous sequences of non-sister chromatids of homologous chromosomes. This contributes to increase in diversity as different combinations of alleles (of different genes) come together in a given linkage group as a consequence .

It occurs during chiasma formation in prophase -I.

d) independent assortment states that the separation of 2 alleles of a gene (present on a pair of homologous chromosome) during meiosis -I is independent of separation of another allele pair of a different gene.

But if the genes , belonging to the same linkage group) are far apart (unlinked) , homologous recombination helps the 2 pairs of alleles of 2 different genes to assort independently. The alleles present on the same chromosome can get separated due to homologous recombination allowing them to land on the other homologue which would then go in a separate gamete.

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