Answer to Question #105946 in Cell Biology for Julia Woy

Question

what the purpose of meiosis is, how the cell reduces the chromosome number in half and the three ways that genetically different cells are made. Be sure to explain the ways and not just list them.

Answer 1

The main purpose of meiosis is to transfer genetic material by reducing the number of cellular chromosomes by half (from 46 to 23) using a twofold process of genetic information division. The first process is reduction division, which leads to two gamete cells, each containing 23 chromosomes. Second process is equational division or meiosis II, where reproductive cells further split into four, each containing 23 chromosomes.

On the other hand, genetically different cells can be formed in the three ways as highlighted below.

1.     Mitosis gene transmission

Normally, mitosis takes place in somatic cells, which ultimately leads to creation of duplicate cells that contain similar genetic materials due to inheritance of similar chromosomal sets from parent organism. However, there are instances where genetic variation occurs as a result of spontaneous mutations as in the case of large polytene chromosomes in Drosophila cells.

2.     Meiosis gene transmission

In this process, genetic variability in cells occurs through independent assortment where genes get mixed up. Further, sexual reproduction expands cell variability due to difference in parental genotype.

3.     Aberrations which change chromosome number

Here, genetic variability results from the inheritance of odd numbers of chromosomes at segregation period during chromosomes replication.