Comparison of Meiosis and Mitosis

When comparing mitosis and meiosis, on one hand, the similarities of these processes are revealed, and on the other, differences. Both processes are mechanisms of cell division of eukaryotes and lead to an increase in the number of cells. However, mitosis serves to multiply somatic cells, i.e., cells of the body, while meiosis forms the basis of the formation of sex cells. In the first case, the body itself grows, in the second case, the possibility of sexual reproduction is provided.

Cells that enter into both mitotic and meiotic division contain the same amount of hereditary information. In both cases a diploid set of chromosomes is contained, and each chromosome consists of two chromatids. In other words, the cells contain 2n 4c (pairs of homologous chromosomes or tetrads of homologous chromatids). Interphase before meiosis and mitosis are approximately the same.

The most important difference of meiosis is the decrease in the number of chromosomes in daughter cells in half. Therefore, meiosis is also called reductional division. In the case of mitosis, the amount of genetic information in the daughter cells remains the same as in the maternal.

Meiosis includes two divisions. After the first division, two cells are formed. The amount of hereditary information in them is reduced to 1n 2c. That is, homologous chromosomes divide into different cells, but continue to consist of two chromatids. These two daughter cells enter the second division, resulting in the formation of four cells, the chromosomes of which do not have homologous companions and consist of only one chromatid (1n 1c).

Mitosis proceeds in one division. Its result is two cells with the amount of genetic information equal to 2n 2c, that is, each chromosome has homologous to itself, but all chromosomes consist of one chromatid.

Mitosis generates genetically identical cells. In contrast, as a result of meiosis, four genetically non-identical cells are formed. During the first meiotic division, crossing-over occurs, i.e. exchange of sites, between homologous chromosomes. As a result, the genes are recombined. There is also an independent divergence between chromosomes and chromatids in both divisions. This means that each chromosome or chromatid can get into one cell in different combinations with others.

The mechanism of the second meiotic division is similar to mitotic division. In both cases, the chromatids of chromosomes, which are separating during the anaphase period, diverge to the poles.

Phases of mitosis and meiosis have the same names (prophase, metaphase, anaphase, telophase), in many respects the processes occurring in them are similar. In meiosis, due to two divisions, there are prophase I, metaphase I, etc., and also prophase II, etc. There is a short interphase between the two divisions, which is called interkinesis. Prophase I can be very long, at this time, conjugation and crossing-over of chromosomes occur. Therefore, meiosis is longer in time than mitosis.