Questions on mitosis

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lmenwe
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Questions on mitosis

Post by lmenwe » Sat Jul 29, 2006 7:34 am

Please help me to solve these questions. Thanks
Why do you suppose cytokinesis generally occurs in the cell's midplane?
What would happen if a cell underwent mitosis but not cytokinesis?

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Navin
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Post by Navin » Sat Jul 29, 2006 12:24 pm

I have a strange feeling that you have no clue as to what cytokinesis is.

So to help you out, here is a link on cytokinesis: http://en.wikipedia.org/wiki/Cytokinesis
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Post by MrMistery » Sat Jul 29, 2006 7:26 pm

actually in plant cells it is fairly common for cytokinesis to occur unequally, not in the middle, and distribue more cytoplasm to one daughter cell and less to the other. It is done to create a polarity of the cell.
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Post by lmenwe » Sun Jul 30, 2006 1:44 am

Please I know what is cytokinesis. I want to know why cytokinesis occur at the midplane and what would occur if after mitosis but cytokinesis doesn't occur. Does the cell will die if cytokinesis doesn't happen?

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Post by victor » Sun Jul 30, 2006 2:38 am

mitosis = karyokinesis + cytokinesis

I think what you mean is what would happen if karyokinesis sin't followed by cytokinesis...well, it's simple...there'll be a binucleate stadium.. :lol:
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Post by sdekivit » Sun Jul 30, 2006 2:39 pm

a syncytium is formed then :D

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Post by xand_3r » Sun Jul 30, 2006 4:34 pm

Well, not exactly. A syncitium reffers to a group of cells acting as a hole. For example, the smooth muscle cells in the wall of the digestive tube form a syncitium (depolarization in one muscle cell will be followed by depolarization in neighbouring cells and so on). The action potential in a syncitium isn't conducted through nerve fibers but through the cells themselves. This is done through specialized cell junctions called GAP junctions. These junctions are formed from large numbers of conexones (small protein channels, 6 proteins each called conexines) so ions can flow from a cell to another but not other larger components such as organelles or larege proteins.

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Post by MrMistery » Sun Jul 30, 2006 5:20 pm

No, xand_3r, sdekivit is right. Anatomy books do say that the heart muscle or the muscle cells in the wall of the small intestine function as a syncitium. But the strict definition of a syncitium is a cellular mass with many nuclei that originate in the same nucleus. As opposed to a plasmodium that is composed of many cells that fuse without the nuclei fusing.
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Post by lmenwe » Mon Jul 31, 2006 3:31 am

Why do you suppose cytokinesis generally occurs in the cell's midplanes?

Because in that way cell organelles get equally partitioned between the daughter cells. Can I answer it in this way?

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Post by victor » Mon Jul 31, 2006 6:22 am

I can think that physically, the midplane is the most vulnurable part for cytokinesis due to both right and left mass polarity...But, as like always, excecptions always occur in this kind of situation.. :lol:
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Post by sdekivit » Mon Jul 31, 2006 7:48 am

xand_3r wrote:Well, not exactly. A syncitium reffers to a group of cells acting as a hole. For example, the smooth muscle cells in the wall of the digestive tube form a syncitium (depolarization in one muscle cell will be followed by depolarization in neighbouring cells and so on). The action potential in a syncitium isn't conducted through nerve fibers but through the cells themselves. This is done through specialized cell junctions called GAP junctions. These junctions are formed from large numbers of conexones (small protein channels, 6 proteins each called conexines) so ions can flow from a cell to another but not other larger components such as organelles or larege proteins.


you don't have to explain what gap junctions are :) but a syncytium is, as MrMistery already explained, a group of cells that didn't undergo division of the cell membranes, but only nuclear division.

Examples of syncytia: the syncytiotrophoblast in embryogenesis, the syncytial blastoderm at the early development of Drosophila

--> thus a syncytium is a mass of cells that only underwent nuclear division but not cellular division creating new cells

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Post by xand_3r » Mon Jul 31, 2006 11:13 am

Yes, you're right. I forgot about the sincitiotrofoblast. Sorry.

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