Centrosome

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Diagram of typical animal cell, showing subcellular components. Organelles:
(1) nucleolus
(2) nucleus
(3) ribosomes (little dots)
(4) vesicle
(5) rough endoplasmic reticulum (ER)
(6) Golgi apparatus
(7) Cytoskeleton
(8) smooth ER
(9) mitochondria
(10) vacuole
(11) cytoplasm
(12) lysosome
(13) centrioles within centrosome

In cell biology, the centrosome is an organelle that is the main place where cell microtubules get organised. They occur only in animal cells. Also, it regulates the cell division cycle, the stages which lead up to cell division.

The centrosome was discovered by Edouard Van Beneden in 1883,[1] and was described and named in 1888 by Theodor Boveri.[2]

The centrosome has apparently only evolved in metazoan eukaryotic cells.[3] Fungi and plants use other structures to organize their microtubules.[4] Although the centrosome has a key role in efficient mitosis in animal cells, it is not necessary.[5]

Centrosomes are composed of two centrioles at right angles, surrounded by a shapeless mass of protein.

Roles of the centrosome[change | change source]

The centrosome is copied only once per cell cycle so that each daughter cell inherits one centrosome, containing two centrioles. The centrosome replicates during the interphase 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.

Interestingly, centrosomes are not required for the progression of mitosis. When the centrosomes are irradiated by a laser, mitosis proceeds with a normal spindle. 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]

Although centrosomes are not required for mitosis or survival of the cell, they are required for survival of the organism. Cells without centrosomes lack certain microtubules. With centrosome the cell division is much more accurate and efficient. Some cell types arrest in the following cell cycle when centrosomes are absent, but this is doesn't happen always.

References[change | change source]

  1. Wunderlich V. 2002. JMM - past and present. Journal of Molecular Medicine 80 (9): 545–548. doi:10.1007/s00109-002-0374-y. PMID 12226736.
  2. Boveri, Theodor (1888). Zellen-Studien II: Die Befruchtung und Teilung des Eies von Ascaris megalocephala.. Jena: Gustav Fischer Verlag. http://www.biodiversitylibrary.org/item/29952.
  3. Bornens M.; Azimzadeh J. 2007. Origin and Evolution of the Centrosome. Advances in experimental medicine and biology 607: 119–129. doi:10.1007/978-0-387-74021-8_10. PMID 17977464.
  4. Schmit 2002. Acentrosomal microtubule nucleation in higher plants. International Review of Cytology 220: 257–89. doi:10.1016/S0074-7696(02)20008-X. PMID 12224551.
  5. Mahoney N.M.; Goshima G.; Douglass A.D.; Vale R.D. 2006. Making microtubules and mitotic spindles in cells without functional centrosomes. Current Biology 16 (6): 564–569. doi:10.1016/j.cub.2006.01.053. PMID 16546079.
  6. Rieder CI; Faruki S; Khodjakov A. 2001. The centrosome in vertebrates: more than a microtubule-organizing center. Trends in Cell Biology 11 (10): 413–9. doi:10.1016/S0962-8924(01)02085-2. ISSN 0962-8924. PMID 11567874.