Rare cell division

[amberdagp]

Hi,

Some cells in the body spend a large part of their time uncergoing cell division, whereas come cells rarely divide. Why is this? thank you in advance

[mschristine]

Okay, so I'm only working on what high school knowledge I have, but...

1) cells divide because they either are getting to big and that puts a strain on their genetic material and because the surface to volume ratio of the cell makes it difficult to transport material in and out of the cell. So I guess that raises the question as to why some cells get bigger than others. I guess some cells get/req. more "food" than others and therefore have to divide.

2) cells divide to repair damage. Say you scrape your elbow. Well, cells need to divide to repair that damage. So, some cells are more susceptible to damage and therefore need to divide more often. Another example is the lining of the intestines and stomach. In the intestines cells need to continually divide because of all the material constantly being pushed though. And in the stomach, cells endure the stomach acid and so have to also keep dividing.

Hope that helped. I'm sure there are plenty more (and detailed) factors that someone here may know. Maybe you can look into reasons for why some cells, such as nerve cells, stop dividing.

[amberdagp]

Thank you for your reply, the main thing is i cant really find any explanation on why some cells stop dividing, as you said nerve cells (mainly in the brain), cardiac cells and liver cells, why is it they stop dividing? are they just not programmed to do this?

[MrMistery]

from the above answer, 2) is correct, 1) is false. it's not that cells need to divide because they get too big. A lot of cells spend their time in G0, in a phase outside the cell cycle. only when they receive the proper signals do they reenter the cell cycle.
the key thing to keep in mind is that mammalian cells cannot divide by default, like bacteria and yeast can. they need special molecules on the outside called growth factors, and those factors trigger cell division. Also, different growth factors trigger division in different cells. It is one way to look at it that those highly specialized cells cannot enter the cell cycle regardless of what growth factors are present because no factors can induce them to exit from G0. Sure, even if they did enter the cell cycle they couldn't carry out cytokinesis, they are just too specialized for that.

Does that clear things up?

[amberdagp]

from the above answer, 2) is correct, 1) is false. it's not that cells need to divide because they get too big. A lot of cells spend their time in G0, in a phase outside the cell cycle. only when they receive the proper signals do they reenter the cell cycle.
the key thing to keep in mind is that mammalian cells cannot divide by default, like bacteria and yeast can. they need special molecules on the outside called growth factors, and those factors trigger cell division. Also, different growth factors trigger division in different cells. It is one way to look at it that those highly specialized cells cannot enter the cell cycle regardless of what growth factors are present because no factors can induce them to exit from G0. Sure, even if they did enter the cell cycle they couldn't carry out cytokinesis, they are just too specialized for that.

Does that clear things up?

yep that sums it up:) thank you vmuch!:)