Differences between Mitosis-Meiosis
Contents
Mitosis vs. meiosis[edit]
Mitosis and meiosis are the two primary processes of nuclear division in eukaryotic cells. Mitosis produces two daughter cells that are genetically identical to the parent cell. This type of division occurs in somatic cells and is responsible for growth, tissue repair, and asexual reproduction. Meiosis is a specialized division that occurs in germ cells to produce gametes. It involves two rounds of division that reduce the chromosome number by half, resulting in four haploid daughter cells. Each of these cells is genetically distinct from the parent cell and from other daughter cells.[1]
Comparison table[edit]
| Feature | Mitosis | Meiosis |
|---|---|---|
| Purpose | Growth, tissue repair, asexual reproduction | Production of gametes for sexual reproduction |
| Where it occurs | Somatic cells (all body cells) | Germ cells (gonads) |
| Number of divisions | One | Two (Meiosis I and Meiosis II) |
| Number of daughter cells | Two | Four |
| Genetic composition | Genetically identical | Genetically unique |
| Chromosome count | Remains diploid (2n) | Reduced to haploid (n) |
| Homologous pairing | Absent | Present (Synapsis in Prophase I) |
| Genetic recombination | Does not occur | Occurs via crossing over in Prophase I |
| Centromere split | Occurs during anaphase | Occurs only during anaphase II |
Comparison of mechanisms[edit]
The mitotic cycle consists of a single round of DNA replication followed by one nuclear division. The process is divided into four main stages: prophase, metaphase, anaphase, and telophase. During metaphase, individual chromosomes align at the cell equator. In anaphase, sister chromatids separate and move toward opposite poles. This ensures that each daughter cell receives an exact copy of the parent genome.[2]
Meiosis involves one round of DNA replication followed by two successive divisions. Meiosis I is a reductional division. During prophase I, homologous chromosomes undergo synapsis and form tetrads. Recombination occurs as non-sister chromatids exchange segments of DNA. In metaphase I, homologous pairs align at the equator. This alignment is random, a principle known as independent assortment. Anaphase I separates the homologous chromosomes, while sister chromatids remain attached at their centromeres. Meiosis II follows without further DNA replication. This second stage resembles mitosis because sister chromatids finally separate during anaphase II.[3]
Genetic variation[edit]
Mitosis maintains genetic stability within a cell lineage. Any variation between mitotic daughter cells is typically the result of spontaneous mutations. Meiosis generates genetic diversity through three specific events: crossing over during prophase I, the independent assortment of chromosomes during metaphase I, and the subsequent random fusion of gametes during fertilization. These mechanisms produce new combinations of alleles in offspring.
History of discovery[edit]
Walther Flemming provided the first detailed account of mitosis in the 1870s. He studied the division of cells in salamander larvae and used dyes to observe the thread-like structures he termed chromosomes. Oscar Hertwig described meiosis in 1876 during his research on sea urchin eggs. He noted that fertilization required the fusion of two nuclei, which suggested that germ cells must contain half the standard number of chromosomes. August Weismann later identified the hereditary significance of this reduction in 1890.
References[edit]
- ↑ Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell. 4th edition. New York: Garland Science; 2002. Mitosis.
- ↑ Campbell NA, Reece JB. Biology. 7th edition. San Francisco: Pearson, Benjamin Cummings; 2005.
- ↑ Nature Education. Meiosis, Genetic Recombination, and Sexual Reproduction. Scitable. 2010.
