G0 Phase in Mitosis: Causes & Effects

[zk4586]

Can someone tell me some of the hypothesized causes of why a cell will enter into the resting G0 phase (that's, G-zero phase) during mitosis? My AP bio. textbook doesn't say why the cell will sometimes pause before DNA replication.

 

[iansmith]

Cell going into G-0 phase are non-proliferating cell such as CNS cell, muscle cells. In vitro you can force cell out of the G-0 or other type of cell to go in the G-0.

from http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=153779
In vitro studies have examined the link between aberrant cell cycle reentry and neuronal cell death. These results demonstrate that although at least some postmitotic neurons retain the capacity to respond to growth factors by reentering into the cell cycle, such stimulation causes apoptosis rather than proliferation.

The role of the G-0 phase is to stop proliferation because can you imagine if the CNS you always regenarated its cell pool. We probably have memory problem and other problem due to losing connection.
For muscle we would lose our strengh.

Non-proliferating cells are there to make we keep a certain level of physical and mental shape.

 

[Monique]

Doesn't G0 also allow for differentiation? A cell continuously going through mitosis wouldn't have time for that.

And zk4586, are you sure you are not talking about G1? Since you seem to be talking about a pause before DNA replication? G1 is there to assess environmental conditions, once a cell goes through the restriction point (or start in yeasts) there is no way back so it needs to be sure that it really needs to replicate its DNA.

 

[zk4586]

From my biology textbook:

Most of the variation in the length of the cell cycle from one organism or tissue to the next occurs in the G-1 phase. Cells often pause in G-1 before replication and enter a resting state called G-0 phase; they may remain in this phase for days to years before resuming cell division. At any given time, most of the cell's in an animals body are in G-0 phase. Some such as muscle cells and nerve cells remain there permanently; others, such as liver cells, can resume G-1 phase in response to factors released during injury.

 

[Monique]

Cells often pause in G-1 before replication and enter a resting state called G-0 phase

That sentence is very misleading. G1 is a resting phase before replication, it is part of the cycle of mitosis. G0 is a specialized state, not part of mitosis, for when cell doesn't need to replicate.

 

[zk4586]

Textbooks...[sighs and throws hands up in the air]. I asked my teacher and he said the same thing. Thanks for clearing that up.

 

[Monique]

Glad to could have been of help :)

 

[Another God]

From Molecular Biology of the Cell, Alberts 2003:
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For an animal cell to proliferate, nutrients are not enough. It must also receive stimulatory extracellular signals, in the form of mitogens...Mitogens act to overcome intracellular braking mechanisms that block progress through the cell cycle.

...

In the absence of a mitogenic signal to proliferate, Cdk inhibition in G₁ is maintained, and the cell cycle arrests. In some cases, cells partly disassemble their cell-cycle control systems and exit from the cycle to a specialized, non-dividing state called G₀.

Most cells in our body are G₀...neuron and muscle...terminally differentiated...liver cells...stimulated to divide if the liver is damaged...
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etc etc.

If you want to know more about any parts of the cell cycle, please ask, I need to know all of this stuff myself. Final exams are coming, and I plan on answering a question on this very topic

 

[Monique]

Nice, I am going through the same book :)

 

[mheuer3]

Does anyone have examples of a few different cells that go into G0 Phase? It doesn't say in my textbook and my class is suppose to find these examples for extra credit.

 

[BoomBoom]

Does anyone have examples of a few different cells that go into G0 Phase? It doesn't say in my textbook and my class is suppose to find these examples for extra credit.

Nice...a 6 year old necro-post!

(Without directly answering)...try to think of some types of cells that do not typically go through cell division.