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Meiosis (/ m aɪ ˈ oʊ s ɪ s / ⓘ; from Ancient Greek μείωσις (meíōsis) 'lessening', (since it is a reductional division) [1] [2] is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, the sperm or egg cells.
Meiosis generates genetic variation in the diploid cell, in part by the exchange of genetic information between the pairs of chromosomes after they align (recombination). Thus, on this view, [ 28 ] an advantage of meiosis is that it facilitates the generation of genomic diversity among progeny, allowing adaptation to adverse changes in the ...
The SC is composed of proteins like SYCP1, SYCP2, and SYCP3, which work together to stabilize the homologs and promote homologous or meiotic recombination, where homologous chromosomes exchange genetic material. Any flaws in its formation lead to failures in meiotic recombination, chromosome segregation, and the completion of meiosis. [7]
Zygotene (from greek "paired threads" [1]) is the second stage of prophase I during meiosis, the specialized cell division that reduces the chromosome number by half to produce haploid gametes. It follows the Leptotene stage and is followed by Pachytene stage.
Meiosis is a round of two cell divisions that results in four haploid daughter cells that each contain half the number of chromosomes as the parent cell. [10] It reduces the chromosome number in a germ cell by half by first separating the homologous chromosomes in meiosis I and then the sister chromatids in meiosis II .
Genetic linkage is the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction.Two genetic markers that are physically near to each other are unlikely to be separated onto different chromatids during chromosomal crossover, and are therefore said to be more linked than markers that are far apart.
Various DNA stains are used to treat cells such that condensing chromosomes can be visualized as the move through prophase. [ 4 ] The giemsa G-banding technique is commonly used to identify mammalian chromosomes , but utilizing the technology on plant cells was originally difficult due to the high degree of chromosome compaction in plant cells.
The first theory rests upon the idea that meiosis evolved as another method of DNA repair, and thus crossing-over is a novel way to replace possibly damaged sections of DNA. [9] The second theory comes from the idea that meiosis evolved from bacterial transformation , with the function of propagating diversity.