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meiosis
[ mahy-oh-sis ]
noun
- Cell Biology. part of the process of gamete formation, consisting of chromosome conjugation and two cell divisions, in the course of which the diploid chromosome number becomes reduced to the haploid. Compare mitosis.
- Rhetoric.
- expressive understatement, especially litotes.
meiosis
/ maɪˈɒtɪk; maɪˈəʊsɪs /
meiosis
/ mī-ō′sĭs /
- The process in cell division in sexually reproducing organisms that reduces the number of chromosomes from diploid to haploid (half the original number). Meiosis involves two consecutive divisions of the nucleus and leads to the production of reproductive cells (gametes) in animals and to the formation of spores in plants, fungi, and most algae (the haploid spores grow into organisms that produce gametes by mitosis). Meiosis begins when the chromosomes, which have already duplicated, condense along the center of the nucleus, and pairs of homologous chromosomes undergo crossing over , whereby some of their genetic material is exchanged. The pairs of chromosomes then separate and move to opposite ends of the cell, and the cell itself divides into two cells. In the second stage, each of these two cells also divides into two cells. Meiosis thus produces four cells, each of which contain half the number of chromosomes as the original cell. Some or all of the four cells may become functional gametes or spores.
- Compare mitosis
meiosis
- Division of cells in which four “daughter” cells are produced from one “parent” cell, each with half the genes of the parent. Meiosis is a key process in sexual reproduction . In the ovaries and testes , meiosis produces a great variety of sex cells ( sperm and ova ), because the genes of the parent cell can be split in many different ways. The sex cells combine in fertilization to produce a new individual with the full number of genes — half from each parent. Because the sex cells come in such variety, and come from two parents, there is an enormous number of possible forms for the offspring. ( See chromosomes , genetics , and mitosis .)
Derived Forms
- meiotic, adjective
- meiˈotically, adverb
Other Words From
- mei·ot·ic [mahy-, ot, -ik], adjective
- postmei·otic adjective
Word History and Origins
Word History and Origins
Origin of meiosis1
A Closer Look
Example Sentences
Precursor cells must go through a special type of cell division called meiosis in order to halve their chromosomes.
In Malone’s lab, she fell in love with meiosis, the process by which organisms divvy up genetic information to pass on to future generations.
Gametogenesis, fertilization, and one-division meiosis in Oxymonas.
Meiosis in Barbulanympha following fertilization, autogamy, and endomitosis.
Gametogenesis, fertilization, and one-division meiosis in Saccinobaculus.
Haploid (n) chromosome numbers were determined from cells in diakinesis, metaphase I, and metaphase II of meiosis.
One-division meiosis and autogamy without cell division in Urinympha.
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