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It may occur due to abnormal cell division, either during mitosis, or more commonly from the failure of chromosomes to separate during meiosis or from the fertilization of an egg by more than one sperm. [1] In addition, it can be induced in plants and cell cultures by some chemicals: the best known is colchicine, which can result in chromosome ...
Zygoidy is the state in which the chromosomes are paired and can undergo meiosis. The zygoid state of a species may be diploid or polyploid. [51] [52] In the azygoid state the chromosomes are unpaired. It may be the natural state of some asexual species or may occur after meiosis. In diploid organisms the azygoid state is monoploid.
This is an accepted version of this page This is the latest accepted revision, reviewed on 19 December 2024. Cell division producing haploid gametes For the figure of speech, see Meiosis (figure of speech). For the process whereby cell nuclei divide to produce two copies of themselves, see Mitosis. For excessive constriction of the pupils, see Miosis. For the parasitic infestation, see Myiasis ...
The second theory comes from the idea that meiosis evolved from bacterial transformation, with the function of propagating diversity. [9] In 1931, Barbara McClintock discovered a triploid maize plant. She made key findings regarding corn's karyotype, including the size and shape of the chromosomes.
The situation is quite different from that in animals, where the fundamental process is that a multicellular diploid (2n) individual directly produces haploid (n) gametes by meiosis. In animals, spores (i.e. haploid cells which are able to undergo mitosis) are not produced, so there is no asexual multicellular generation.
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 M phase can be either mitosis or meiosis depending on the type of cell. Germ cells, or gametes, undergo meiosis, while somatic cells will undergo mitosis. After the cell proceeds successfully through the M phase, it may then undergo cell division through cytokinesis.
Diploid males would be infertile, as their cells would not undergo meiosis to form sperm. Therefore, the sperm would be diploid, which means that their offspring would be triploid . Since hymenopteran mother and sons share the same genes, they may be especially sensitive to inbreeding : Inbreeding reduces the number of different sex alleles ...