Question

Meiosis reduces chromosome number and rearranges genetic information. Explain how the reduction and rearrangement are accomplished in meiosis. Several human disorders occur as a result of defects in the meiotic process. Identify one such chromosomal abnormality; what effects does it have on the phenotype of people with the disorder

Answer 1

Answer:

Explanation:

Meiosis is a form of cell division that occurs in the sex cells of organisms. It ensures the reduction of a diploid cell to an haploid cell to allow for the formation of a diploid zygote after fertilization (contribution of both parents haploid sex cells to give a diploid zygote). Thus, this process is very essential and important.

The reduction is accomplished by 2 divisions after the duplication of chromosomes

- first division: separation of homologous pairs of chromosomes (this reduces the total in half)

- second division: separation of sister chromatids of a chromosome.

The rearrangement in meiosis occurs by crossing over/genetic recombination.

This is the exchange of genetic material between homologous pairs of chromosome bringing about a rearrangement and genetic variation

An example of a chromosomal abnormality that arises as a result of defects in this process is the Down Syndrome which is caused by a nondisjunction of the chromosomes 21 pair in a sex cell.

This condition produces offsprings that have some characteristic facial features, short stature etc