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Encyclopedia > Centrosome

In cell biology, the centrosome is the main microtubule organizing center (MTOC) of the animal cell as well as a regulator of cell-cycle progression. It was discovered in 1888 by Theodor Boveri and was described as the 'special organ of cell division.'[citation needed] The centrosome is thought to have evolved only in the metazoan lineage of eukaryotic cells.[1] Fungi and plants use other MTOC structures to organize their microtubules.[2][3] Although the centrosome has a key role in efficient mitosis in animal cells, it is not necessary.[4] Cell biology (also called cellular biology or formerly cytology, from the Greek kytos, container) is an academic discipline that studies cells. ... MTOC or microtubule-organizing center is a structure found in all plant and animal cells from which microtubules radiate. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... The cell cycle, or cell-division cycle, is the series of events that take place in a eukaryotic cell leading to its replication. ... Theodor Boveri (1862 – 1915) was a German biologist whose work with sea urchins showed that it was necessary to have all chromosomes present in order for proper embryonic development to take place. ... Phyla Radiata Cnidaria Ctenophora - Comb jellies Bilateria Protostomia Acoelomorpha Platyhelminthes - Flatworms Nemertina - Ribbon worms Gastrotricha Gnathostomulida - Jawed worms Micrognathozoa Rotifera - Rotifers Acanthocephala Priapulida Kinorhyncha Loricifera Entoprocta Nematoda - Roundworms Nematomorpha - Horsehair worms Cycliophora Mollusca - Mollusks Sipuncula - Peanut worms Annelida - Segmented worms Tardigrada - Water bears Onychophora - Velvet worms Arthropoda - Insects, etc. ... For the fictional character, see Fungus the Bogeyman. ... For other uses, see Plant (disambiguation). ... Mitosis divides genetic information during cell division. ...


Centrosomes are composed of two orthogonally arranged centrioles surrounded by an amorphous mass of pericentriolar material (PCM). The PCM contains proteins responsible for microtubule nucleation and anchoring[5] including γ-tubulin, pericentrin and ninein. Each centriole generally comprises nine triplet microtubule blades in a pinwheel structure as well as centrin, cenexin and tektin.[6] In mathematics, orthogonal is synonymous with perpendicular when used as a simple adjective that is not part of any longer phrase with a standard definition. ... A centriole showing the nine triplets of microtubules. ... An amorphous solid is a solid in which there is no long-range order of the positions of the atoms. ... Microtubules are filaments of the cytoskeleton. ...

Contents

!Roles of the centrosome!


Centrosomes are often associated with the nuclear membrane during interphase of the cell cycle. In mitosis the nuclear membrane breaks down and the centrosome nucleated microtubules can interact with the chromosomes to build the mitotic spindle. Mitosis divides genetic information during cell division. ... Microtubules are one of the components of the cytoskeleton. ... This article is about the biological chromosome. ... Micrograph showing condensed chromosomes in blue and the mitotic spindle in green during prometaphase of mitosis The mitotic spindle (a. ...


The mother centriole, the one that was inherited from the mother cell, also has a central role in making cilia and flagella.[6] cross-section of two cilia, showing 9+2 structure A cilium (plural cilia) is a fine projection from a eukaryotic cell that constantly beats in one direction. ... A flagellum (plural, flagella) is a whip-like organelle that many unicellular organisms, and some multicellular ones, use to move about. ...


The centrosome is duplicated only once per cell cycle so that each daughter cell inherits one centrosome, containing two centrioles. The centrosome replicates during the S phase of the cell cycle. During the prophase of mitosis, the centrosomes migrate to opposite poles of the cell. The mitotic spindle then forms between the two centrosomes. Upon division, each daughter cell receives one centrosome. Aberrant numbers of centrosomes in a cell have been associated with cancer. Doubling of a centrosome is similar to DNA replication in two respects: the semiconservative nature of the process and the action of cdk2 as a regulator of the process.[7] But the processes are essentially different in that centrosome doubling does not occur by template reading and assembly. The mother centriole just aids in the accumulation of materials required for the assembly of the daughter centriole.[8] The cell cycle, or cell-division cycle, is the series of events that take place in a eukaryotic cell leading to its replication. ... DNA replication. ... Newt lung cell in Prophase, with the mitotic spindles stained green and the cell nucleus and chromatin stained blue. ... Mitosis divides genetic information during cell division. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ... DNA replication. ... A summary of the three postulated methods of DNA synthesis Semiconservative replication describes the method by which DNA is replicated in all known cells. ... Diavik (ICAO CDK2, IATA N/A) is a private aerodrome in the Northwest Territories that serves the Diavik Diamond Mine. ...


Interestingly, centrosomes are not required for the progression of mitosis. When the centrosomes are irradiated by a laser, mitosis proceeds normally with a morphologically normal spindle. Moreover, development of the fruit fly Drosophila is largely normal when centrioles are absent due to a mutation in a gene required for their duplication.[9] In the absence of the centrosome the microtubules of the spindle are focused by motors allowing the formation of a bipolar spindle. Many cells can completely undergo interphase without centrosomes.[6] Type species Drosophila funebris (Fabricius, 1787) Drosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called fruit flies, or more appropriately vinegar flies, wine flies, pomace flies, grape flies, and picked fruit-flies, a reference to the characteristic of many species to linger...


Image File history File links Download high resolution version (804x683, 216 KB) Summary Figure 1: Role of the centrosome in cell cycle progression. ...


Figure 1: Role of the centrosome in cell cycle progression.[10]


Although Adam Engel centrosomes are not required for mitosis or survival of the cell, they are required for survival of the organism. Acentrosomal cells lack radial arrays of astral microtubules. They are also defective in spindle positioning and in ability to establish a central localization site in cytokinesis. The function of centrosome in this context is hypothesized to ensure the fidelity of cell division as it is not necessary but greatly increases the efficacy. Some cell types arrest in the following cell cycle when centrosomes are absent. This is not a universal phenomenon. Astral microtubule in a mammalian cell Astral microtubules are a subpopulation of microtubules, which only exist during and immediately before mitosis. ... This does not adequately cite its references or sources. ...


When the nematode C. elegans egg is fertilized the sperm delivers a pair of centrioles. These centrioles will form the centrosomes which will direct the first cell division of the zygote and this will determine its polarity. It is not yet clear whether the role of the centrosome in polarity determination is microtubule dependent or independent. Binomial name Caenorhabditis elegans Wild-type C. elegans hermaphrodite stained to highlight the nuclei of all cells Caenorhabditis elegans () is a free-living nematode (a roundworm), about 1 mm in length, which lives in a temperate soil environment. ... It has been suggested that Biparental zygote be merged into this article or section. ...


Centrosome Genome

Recent research in 2006[11] indicates that centrosomes may have their own genome, previously known only in nuclei, mitochondria and chloroplasts. Unlike the latter, it is RNA-based rather than DNA-based, and apparently includes an RNA sequence capable of duplicating the centrosome genome. The putative centrosome genome RNA sequences were purified from surf clam eggs, were found in "few to no" other places in the cell, and do not appear in existing genome databases.


The existence of nucleotides associated with the centrosome remains controversial. Many studies have investigated whether nucleotides associate with the centrosome with varying results.


References

  1. ^ Bornens M, Azimzadeh J (2007). "Origin and evolution of the centrosome". Adv. Exp. Med. Biol. 607: 119–29. PMID 17977464.
  2. ^ Schmit AC (2002). "Acentrosomal microtubule nucleation in higher plants". Int. Rev. Cytol. 220: 257–89. PMID 12224551.
  3. ^ Jaspersen SL, Winey M (2004). "The budding yeast spindle pole body: structure, duplication, and function". Annu. Rev. Cell Dev. Biol. 20: 1–28. doi:10.1146/annurev.cellbio.20.022003.114106. PMID 15473833.
  4. ^ Mahoney NM, Goshima G, Douglass AD, Vale RD (2006). "Making microtubules and mitotic spindles in cells without functional centrosomes". Curr. Biol. 16 (6): 564–9. doi:10.1016/j.cub.2006.01.053. PMID 16546079.
  5. ^ B. Edde, J. Rossier, J.P. Le Caer, E. Desbruyeres, F. Gros & P. Denoulet (1990). "Posttranslational glutamylation of alpha-tubulin". Science 1990: 83-85.
  6. ^ a b c Rieder, CL, S Faruki and A Khodjakov (2001) TRENDS in Cell Biology 11 10:413-418.
  7. ^ Tim Stearns; Centrosome Duplication:A Centriolar Pas de Deux; Cell, Vol. 105, 417–420, May 18, 2001,
  8. ^ A. Rodrigues-Martins, M. Riparbelli, G. Callaini, D. M. Glover, M. Bettencourt-Dias; Revisiting the Role of the Mother Centriole in Centriole Biogenesis; Science 18 May 2007: Vol. 316. no. 5827, pp. 1046 - 1050; DOI: 10.1126/science.1142950
  9. ^ Basto, R, et al. (2006) Cell 125: 1375 -1386.
  10. ^ Doxsey, S., W. Zimmerman and K. Mikule (2005) TRENDS in Cell Biology 15 6: 303-310.
  11. ^ Alliegro, M.C., Alliegro, M.A., and R.E. Palazzo. 2006. Proc. Natl. Acad. Sci. USA, 103(24):9034-8 (as reported in Scientific American, p32, August 2006). PMID 16754862

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Science is the journal of the American Association for the Advancement of Science (AAAS). ...

Additional images

Schematic of typical animal cell, showing subcellular components. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... In spermatozoa of many animals, the acrosome is an organelle that develops over the anterior half of the spermatozoons head. ... Plant cells separated by transparent cell walls. ... Look up cell membrane in Wiktionary, the free dictionary. ... A centriole showing the nine triplets of microtubules. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Not to be confused with Psyllium. ... For the insect anatomical structure, see Antenna (biology). ... Schematic showing the cytoplasm, with major components of a typical animal cell. ... The endoplasmic reticulum or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport of proteins to be used in the cell membrane (e. ... In biology an endosome is a membrane-bound compartment inside cells. ... Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. ... Various organelles labeled. ... In a biological cell, a melanosome is an organelle containing melanin, the most common light-absorbing pigment found in the animal kingdom. ... Electron micrograph of a mitochondrion showing its mitochondrial matrix and membranes In cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed organelle that is found in most eukaryotic cells. ... A diagram of the structure of a Myofybril Myofibrils (obsolete term: sarcostyles) are cylindrical organelles, found within muscle cells. ... HeLa cells stained for DNA with the Blue Hoechst dye. ... The nucleolus is contained within the cell nucleus. ... Parenthesomes are found in basidiomycete fungus. ... Basic structure of a peroxisome Peroxisomes are ubiquitous organelles in eukaryotes that participate in the metabolism of fatty acids and other metabolites. ... Plant cells with visible chloroplasts. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... Schematic of typical animal cell, showing subcellular components. ... In cell biology, a vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer. ...

  Results from FactBites:
 
Meiosis - Wikipedia, the free encyclopedia (2426 words)
The kinetochore functions as a motor, pulling the chromosome along the attached microtubule toward the originating centriole, like a train on a track.
The new equatorial plane is rotated by 90 degrees when compared to meiosis I, perpendicular to the previous plane.
This is followed by anaphase II, where the centromeres are cleaved, allowing the kinetochores to pull the sister chromatids apart.
  More results at FactBites »

 
 

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