Cell division and cancer
Name: Loretta L Lamb
What is the mechanism that causes cells to begin the mitotic process?
I understand the process itself and I have an understanding of DNA
replication, but I can't seem to find out what it is that starts the
actual process. I mean, a cell just doesn't wake up one morning and
say, "I think I'll divide today!"
Oh, and one more question....what causes cells to stop dividing?
I know about contact inhibition, but surely there is more to this.
And speaking of this, psoriasis is caused by cells that don't stop
dividing when they should, right? So how does this differ from cancer?
Thanks for your help!!
You ask wonderful questions - these questions are occupying a lot
of scientists right now. There are some unknown messages that cells
receive once their volume is as great as their surface area can
support with nutrients. This ratio seems to be the trigger for
mitosis in many cells. There is also some intriguing evidence that
cells can only divide (in humans) a finite number of times, then there
are too many mistakes or changes for effectively continuing: there seems to be a cellular clock involved in aging and somehow connected to cell division, keeping track of how many times each cell divides.
I'm not knowledgeable enough about psoriasis to explain the difference
from cancer, but I'll try to find out and let you know.
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Update: June 2012