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8.3. Differences and similarities between mitosis and meiosis

Similarities and differences between mitosis and meiosis

Similarities between mitosis and meiosis

  • Both mitosis and meiosis start from diploid cells (2n).
  • At the interphace, before mitosis or meiosis, duplication of genetic material occurs.
  • Achromatic spindles are made up of the same types of microtubules and their operation is similar.
  • After telophase, in both cases, comes cytokinesis .

Differences between mitosis and meiosis

  • The meiosis only can occur in diploid cells (or polyploid), while only haploid can roll mitosis.
  • In mitosis there is a single division, while in meiosis there are two consecutive divisions, the first reductional, and the second, equivalent to a mitosis.
  • In mitosis, 2 cells genetically identical to the initial cell (2n) are produced. In meiosis, 4n cells are produced, with half the genetic material of the initial cell.
  • The mitosis is carried somatic cells for growth and repair of tissues in multicellular organisms. Single-celled organisms also use mitosis to reproduce asexually. Meiosis is used for the formation of gametes in sexual reproduction, with half of the genetic material so that, when uniting to form the zygote, the number of chromosomes of the individuals of the species is kept constant.
  • In mitosis the number of chromosomes is not altered. In meiosis, haploid cells, n, are formed with half as many chromosomes as the parent cell.
  • In the prophase I of meiosis tetrads are formed and occurs crossover.
  • In the metaphase of mitosis, chromosomes line up on the equatorial plate by the centromere, which joins sister (identical) chromatids. In metaphase I of meiosis, they are alienated in the equatorial plate by the chiasms joining the recombined tetrads. 
  • In the anaphase of mitosis the two sister chromatids separate. In anaphase I the pairs of homologous chromosomes separate.

Comparison between mitosis and meiosis in relation to the number of chromosomes / chromatids in a human cell 2n = 46

Number of chromosomes per cell Number of chromatids (DNA molecules) per cell
Interphace
G1 phase 46 46
S phase (DNA synthesis) Replication of DNA
G2 phase 46 92
Mitosis
Prophase 46 92
Metaphase 46 92
Anaphase (separation of sister chromatids) 92 92
Telophase 92 92
Cytokinesis . Daughter cells are formed. 46 46
Meiosis (DNA has been duplicated before, at the interphase)
Meiosis I or reductional meiosis
Prophase I (recombination between homologous chromosomes) 46 92
Metaphase I 46 92
Anaphase I (separation of homologous chromosomes) 46 92
Telophase I 46 92
Cytokinesis . End of meiosis I. Daughter cell formation 23 46
Meiosis II or equational mitosis (no change in chromosome number, as in mitosis)
Prophase II 23 46
Metaphase II 23 46
Anaphase II (sister chromatid separation) 46 46
Telophase II 46 46
Cytokinesis . End of meiosis II. Daughter cell formation 23 23