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In cell biology, the centrosome (Latin centrum 'center' + Greek sōma 'body') (archaically cytocentre [1]) is an organelle that serves as the main microtubule organizing center (MTOC) of the animal cell, as well as a regulator of cell-cycle progression. The centrosome provides structure for the cell.
The centrosome cycle is important to ensure that daughter cells receive a centrosome after cell division. As the cell cycle progresses, the centrosome undergoes a series of morphological and functional changes. Initiation of the centrosome cycle occurs early in the cell cycle in order to have two centrosomes by the time mitosis occurs.
The microtubule-organizing center (MTOC) is a structure found in eukaryotic cells from which microtubules emerge. MTOCs have two main functions: the organization of eukaryotic flagella and cilia and the organization of the mitotic and meiotic spindle apparatus, which separate the chromosomes during cell division.
A dicentric chromosome is an abnormal chromosome with two centromeres, which can be unstable through cell divisions. It can form through translocation between or fusion of two chromosome segments, each with a centromere. Some rearrangements produce both dicentric chromosomes and acentric fragments which can not attach to spindles at mitosis. [5]
3D rendering of centrioles showing the triplets. In cell biology a centriole is a cylindrical organelle composed mainly of a protein called tubulin. [1] Centrioles are found in most eukaryotic cells, but are not present in conifers (), flowering plants (angiosperms) and most fungi, and are only present in the male gametes of charophytes, bryophytes, seedless vascular plants, cycads, and Ginkgo.
The centrosome is the coordinating center for the cell's microtubules. A cell inherits a single centrosome at cell division, which is duplicated by the cell before a new round of mitosis begins, giving a pair of centrosomes. The two centrosomes polymerize tubulin to help form a microtubule spindle apparatus.
An MSH4 hypomorphic (partially functional) mutant of S. cerevisiae showed a 30% genome-wide reduction in crossover numbers and a large number of meioses with non-exchange chromosomes. [22] Nevertheless, this mutant gave rise to spore viability patterns suggesting that segregation of non-exchange chromosomes occurred efficiently.
Furthermore, when centrosome number is doubled, tubifex embryos cleave symmetrically, suggesting this monoastral mechanism of asymmetric cell division is centrosome dependent. [26] Helobdella robusta: The leech Helobdella robusta exhibits a similar asymmetry in the first embryonic division as C. elegans and tubifex, but relies on a modified ...