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

Rearrangement takes place at the time of meiosis with the lining of chromosomes pair during the metaphase 1 and 2. Down syndrome is the example of chromosomal abnormality.

•A process in which a single cell differentiates two times to generate four cells comprising half the original amount of genetic information is termed as meiosis.

•During meiosis, the process of rearrangement takes place when the chromosomes line up in pairs at the time of metaphase 1 and 2. Then in anaphase 1 and 2, the separation of these chromosomes takes place and each gamete gets one of each kind of chromosome.  

•One of the examples of chromosomal abnormality is Down syndrome, which is, illustrated by the third copy of chromosome 21. The phenotypic variability, which takes place during Down syndrome is muscle hypotonia at the time of birth, and cognitive impairment.  

Thus, during meiosis reduction and rearrangement of chromosomes takes place, and one of the chromosomal abnormality is the Down syndrome.

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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

dna damages cause changes in the structure of the genetic material and prevents the replication mechanism from functioning and performing properly. dna damage and mutation have different biological consequences. while most dna damages can undergo dna repair, such repair is not 100% efficient.