Mitosis

Mitosis is the cell division process in which a eukaryotic cell divides the chromosomes into two identical sets of two daughter nuclei in its cell nucleus. It is followed by cytokinesis, which equally divides the nuclei, cytoplasm, organelles and cell membrane into two daughter cells. Mitosis and cytokinesis together form the mitotic (M) phase of the cell cycle. The sequence of events are divided into different stages named as prophase, prometaphase, metaphase, anaphase and telophase. Mitosis occurs in different ways in different species. For example, animals undergo an open mitosis process in which the nuclear envelope breaks down before the chromosomes separate, while fungi and yeast undergo a closed mitosis in which the chromosomes divide within an intact cell nucleus.

Meiosis

Meiosis is a process of reductional division in which the number of chromosomes per cell is halved. Before it begins, the DNA in the original cell is duplicated during S-phase of the cell cycle. Meiosis separates the replicated chromosomes into four haploid gametes or spores. If it produces gametes, these cells should fuse during fertilization to create a new diploid cell or zygote. In plants, meiosis produces spores which results in the formation of haploid cells that can divide vegetatively without undergoing fertilization. The different stages involved in meiosis are meiosis I, prophase I, metaphase I, anaphase I, telophase I and meiosis II. Meiosis is necessary for sexual reproduction and therefore occurs in all eukaryotes that reproduce sexually. Meiosis does not occur in archaea or bacteria as they reproduce asexually through binary fission process.

Difference Between Mitosis and Meiosis

The differences between mitosis and meiosis are as follows:


1.Mitosis takes place within somatic cells (cells that make up the body).
Meiosis takes place within gamete cells (sex cells).

2.One single division of the mother cell results in two daughter cells.
Two divisions of the mother cell result in four meiotic products or haploid gametes.

3.A mitotic mother cell can either be haploid or diploid.
A meiotic mother cell is always diploid

4.The number of chromosomes per nucleus remains the same after division.
The meiotic products contain a haploid (n) number of chromosomes in contrast to the (2n) number of chromosomes in mother cell.

5.It is preceded by a S-phase in which the amount of DNA is duplicated.
In meiosis, only meiosis I is preceded by a S-phase

6.In mitosis, there is no pairing of homologous chromosomes.
During prophase I, complete pairing of all homologous chromosomes takes place.

7.There is no exchange of DNA (crossing-over) between chromosomes.
There is at least one crossing-over or DNA exchange per homologous pair of chromosomes.

8.The centromeres split during anaphase.
The centromeres do separate during anaphase II, but not during anaphase I.

9.The genotype of the daughter cells is identical to that of the mother cells.
Meiotic products differ in their genotype from the mother cell.

10.After mitosis, each daughter cell has exactly same DNA strands.
After meiosis, each daughter cell has only half of the DNA strands.