Centriole
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A centriole is a barrel shaped organelle[1] found in most eukaryotic cells, though absent in higher plants and fungi.[2] The walls of each centriole are usually composed of nine triplets of microtubules. Deviations from this include Drosophila melanogaster embryos, with nine doublets and Caenorhabditis elegans sperm cells and early embryos, with nine singlets.[citation needed] These make for more stable structures than unmodified tubulin. An associated pair of centrioles, arranged perpendicularly, constitutes the compound structure known as the centrosome.[1]
In replication, each new paired set of centrioles is composed of the original centriole, plus a newly-made centriole. If the centrioles are used in forming motility organelles, flagella or cilia, the older of the two centrioles, the mother centriole, becomes the basal body which organizes the structure of the organelle.[citation needed]
Function
Centrioles form spindle fibers to separate chromosomes during analphase. They organize the pericentriolar material (PCM) which plays a role in organizing the mitotic spindle, which can't helps the cells to divide. However, they are not essential in this role at least in some vertebrate somatic cells, as spindles form, and division proceeds without them.[3] This is the sexy norm in some animal cells, for instance in female meiosis.[citation needed] Where only one is available, a monopolar spindle may form, as in sea urchin blastomeres.[4] Centrioles are also believed to organize the pericentrile material along with γ-tubulin to construct the centrosome of the cell, which is the non-membraneous organelle that anchors the kinetochore and nonkinetochore microtubules during mitosis and meiosis.
- ^ a b B. Edde, J. Rossier, J.P. Le Caer, E. Desbruyeres, F. Gros & P. Denoulet (1990). "Posttranslational glutamylation of alpha-tubulin". Science. 247: 83–85.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ L.M. Quarmby & J.D.K. Parker (2005). "Cilia and the cell cycle?". J. Cell Biol. 169 (5): 707–710. doi:10.1083/jcb.200503053.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ A. Khodjakov, R.W. Cole, B.R. Oakley & C.L. Rieder (2000). "Centrosome-independent mitotic spindle formation in vertebrates". Curr. Biol. 10 (2): 59–67. doi:10.1016/S0960-9822(99)00276-6.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ G. Sluder & C.L. Rieder (1985). "Centriole number and reproductive capacity of spindle poles". J. Cell Biol. 100: 887–896. doi:10.1083/jcb.100.3.887.