Difference Between Mitosis And Meiosis

Mitosis and meiosis both occur in the M phase of the cell cycle, and are the methods of cell division to form somatic cells and gametes, respectively. They are both complex processes that form more than one daughter cell from one parent cell, and they have many similarities and differences, which will be discussed in this essay.

Mitosis is the type of cell division that occurs in all somatic cells. Its purpose is to produce two genetically identical daughter cells. Before the process of mitosis starts, DNA replicates and the resulting sister chromatids are held together by cohesin proteins. (Alberts et al., 2010.) The centrosome, which is the principle microtubule organising centre (MTOC), also duplicates. In prophase, the two centrosomes

The microtubule spindles attach to the kinetochores in metaphase II, causing the chromosomes to line up, and at the start of anaphase II, the remaining cohesins at the centromere break down, so that the sister chromatids are able to separate and move to opposite ends of the cell. (Alberts et al., 2008.) They then undergo telophase and cytokinesis to produce four haploid cells. (Lodish et al., 2008.)

Mitosis and meiosis are similar methods of cell division, as both produce daughter cells. In both processes, the DNA is replicated beforehand, and they both undergo prophase, metaphase, anaphase and telophase at least once. Mitosis and meiosis II are very similar processes, except mitosis produces diploid somatic cells and meiosis produces haploid gametes. (Tortora and Derrickson,

(Alberts et al., 2010.) Meiosis also takes significantly longer than mitosis, due to prophase I being a long process. (Alberts et al., 2010.) In meiosis, homologous pairs line up and are separated first, whereas in mitosis, homologous pairs are not formed- so in metaphase, homologs line up separately. (Alberts et al., 2010.) Mitosis produces genetically identical daughter cells, whereas meiosis leads to variation due to the production of four non-identical daughter cells. This is because there is no genetic recombination in prophase of mitosis, whereas prophase I of meiosis contains at least one cross-over, resulting in genetic recombination between non-sister chromatids. (Lodish et al., 2008.) Figure 1 illustrates more differences between mitosis and meiosis, for example, the orientation of spindle fibres is the same in mitosis and metaphase II but not metaphase I, and the location of cohesins on the replicated chromosomes are shorter in mitosis than in metaphase