AskDefine | Define centrosome

Dictionary Definition

centrosome n : small region of cytoplasm adjacent to the nucleus; contains the centrioles and serves to organize the microtubules [syn: central body]

User Contributed Dictionary



  1. An organelle, near the nucleus in the cytoplasm of most organisms, that controls the organization of its microtubules

Extensive Definition

In cell biology, the centrosome 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. It was discovered in 1888 by Theodor Boveri and was described as the 'special organ of cell division.' The centrosome is thought to have evolved only in the metazoan lineage of eukaryotic cells. Fungi and plants use other MTOC structures to organize their microtubules. Although the centrosome has a key role in efficient mitosis in animal cells, it is not necessary.
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 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.

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.
The mother centriole, the one that was inherited from the mother cell, also has a central role in making cilia and flagella. 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.
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. 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. 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.


centrosome in Bulgarian: Центрозома
centrosome in Catalan: Centrosoma
centrosome in Czech: Centrozóm
centrosome in German: Zentrosom
centrosome in Spanish: Centrosoma
centrosome in French: Centrosome
centrosome in Italian: Centrosoma
centrosome in Lithuanian: Centrosoma
centrosome in Dutch: Centrosoom
centrosome in Japanese: 中心体
centrosome in Polish: Centrosom
centrosome in Portuguese: Centrossoma
centrosome in Romanian: Centrozom
centrosome in Russian: Центросома
centrosome in Slovak: Centrozóm
centrosome in Serbian: Центрозом
centrosome in Serbo-Croatian: Centrozom
centrosome in Swedish: Centrosom
centrosome in Vietnamese: Trung thể
centrosome in Turkish: Sentrozom
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