G0 phase
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2008-06-04T17:45:48Z
Earthdirt
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rv incorrect information (g0 not syn with interphase)
[[Image:Gray626.png|thumb|right|200px|Many mammal [[cell]]s, such as this [[neuron]], remain permanently or semipermanently in G<sub>0</sub>.]]
{{downsize|title=G<sub>0</sub> phase}}
The '''G<sub>0</sub> phase''' (G sub 0) is a period in the [[cell cycle]] where cells exist in a [[quiescence|quiescent]] state. G<sub>0</sub> is sometimes referred to as a "post-mitotic" state since cells in G<sub>0</sub> are in a [[cell division|non-dividing]] phase outside of the [[cell cycle]]. Cells enter the G<sub>0</sub> phase from a [[cell cycle checkpoint]] in the [[G1 phase|G<sub>1</sub> phase]], such as the [[restriction point]] (animal cells) or the start point (yeast). This usually occurs in response to a lack of [[growth factor]]s or nutrients. During the G<sub>0</sub> phase, the cell cycle machinery is dismantled and [[cyclin]]s and [[cyclin-dependent kinase]]s disappear. Cells then remain in the G<sub>0</sub> phase until there is a reason for them to divide. Some cell types in mature organisms, such as [[parenchymal]] cells of the liver and kidney, enter the G<sub>0</sub> phase semi-permanently and can only be induced to begin dividing again under very specific circumstances; other types, such as [[epithelial cell]]s, continue to divide throughout an organism's life.
Although many cells in the G<sub>0</sub> phase may die along with the organism, this does not mean that cells that enter the G<sub>0</sub> phase are destined to die; this is often simply a consequence of the cell lacking any stimulation to re-enter in the [[cell cycle]].
However, the term "post-mitotic" is sometimes used to refer not only to quiescent cells but also to [[Senescence#Cellular senescence|senescent]] cells. Cellular senescence is a state that occurs in response to DNA damage or degradation that would make a cell's progeny nonviable; it is often a biochemical alternative to the self-destruction of such a damaged cell by [[apoptosis]].
==See also==
* [[Cell Cycle]]
{{Cell cycle}}
[[Category:Cell cycle]]
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