Meiosis vs. Mitosis

Mitosis and meiosis primarily differ from each other with respect to the number of steps involved, genetic recombination events, and final chromosome and daughter cell numbers. 

Most eukaryotic cells divide by mitosis, an equational division, where each diploid parent cell produces two identical diploid daughter cells.

However, each diploid germ cell divides into four genetically distinct haploid daughter cells through meiosis, a reductional division.

Mitosis is a four-stage process – prophase, metaphase, anaphase, and telophase. Meiosis goes through these four stages twice without an intermediate DNA synthesis phase.  

The prophase stage of mitosis is shorter and does not involve the pairing of homologous chromosomes or any recombination. Therefore, all the daughter cells are genetically identical.

In meiosis, prophase I is the longest phase consisting of five substages. In prophase I, two homologous chromosomes pair to form a synaptonemal complex and subsequently recombine to produce four genetically diverse chromatids.

During mitotic metaphase, the individual chromosomes assemble along the equator, whereas during metaphase I of meiosis, pairs of homologous chromosomes align on the equator.

The sister chromatids of each chromosome are held together by cohesin complexes.

The cohesin complexes are completely removed by the end of the mitotic metaphase allowing the sister chromatids to separate and move towards opposite poles.

However, in meiosis I, only the cohesin complexes present on the chromosome arms get detached from the chromatid at the start of the anaphase I, whereas those surrounding the kinetochore remain intact.

Thus, even as the homologous chromosomes are separated and pulled to opposite poles, the sister chromatids remain attached and migrate together.

The second cell division in meiosis II is similar to mitosis. Mitotic anaphase and anaphase II of meiosis involve the separation of two sister chromatids of each homologous chromosome, and subsequent division into two daughter cells - identical and diploid for mitosis but non-identical and haploid for meiosis II. 

The daughter cells arising from meiosis are more likely to have chromosome segregation errors than the ones arising from mitosis. Such chromosome segregation errors produce aneuploid cells with an incorrect number of chromosomes which can lead to diseases like Down syndrome.