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DNA replication question.

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DNA replication question.

Postby lightuplightup » Mon May 23, 2005 10:50 am

I don't understand why the DNA is attached to the cell membrane in primitive cells? Can someone please help- is it anything to do with size???

Also, If you transplanted a shrub from one pot to another- would that stimulate cell division?

Does loss of blood stimulate cell division?

Thanks
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DNA

Postby victor » Mon May 23, 2005 12:57 pm

Um, I don't think that primitive cells have a DNA yet....They're still using RNA to reproduce themselves. But maybe if there're some primitive cells that've already use DNA...I thaink maybe it's because they're still procariotic cells. So, they don't have any special membrane that only covers the nucleus (DNA are in the nucleus). So, what you ask about is procariotic cells.
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Postby MrMistery » Mon May 23, 2005 8:52 pm

According to the general accepted division of life into 3 domains, the domain bacteria contains "the primitive cells". Primitive cells, as in bacteria, ALWAYS have DNA as their nucleic acid, NEVER RNA. The only place where we find RNA as nucleic acid is in viruses, which are not living...
Now, i have checked my microbiology course and couldn't find the information that DNA is attached in the cell membrane. Actually, it even says somewhere that it is dispersed in the cytoplasm. Could you give me the source of that information, please.

Also, If you transplanted a shrub from one pot to another- would that stimulate cell division?

I doubt it. It might stimulate it a litte, but neglijable. I can not see a big factor that could do this

Does loss of blood stimulate cell division?

YES, on the level of the bone marrow in principal and only in case of a semnificant hemoragy. When you lose blood your body needs to "refill" with red blood cells so the stem cells in the bone marrow start dividing faster, i guess.

Hope i didn't say anything wrong and that this helped you
Regards,
Andrew
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Postby James » Mon May 23, 2005 10:48 pm

That's why long distance runners 'drain' themselves; the body creates more blood, then transfuse the blood back in and voila more blood for oxygen transport
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Postby Jelanen » Tue May 24, 2005 3:40 pm

I seem to remember that bacterial DNA is usually attached to the cell membrane. Eukaryotic cells are even more complex, the DNA has a physical 3D address and is rigidly held in place by a network of microtubules.

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Postby MrMistery » Tue May 24, 2005 6:54 pm

The question was deffinetly referring to bacterial DNA Jelanen, since eukaryotic DNA is inside the nucleus. Thanks for the info, i learned something today
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Postby GreenDog » Mon May 30, 2005 10:46 am

Bacterial DNA is definitely attached to the cell membrane. It related to the order in a bacterial cell and affects nucleosome morphology. The connection to the membrane pulls the nucleoid to the sides adding to the order in the cell. In addition the OriC is "hidden" inside the membrane when it is not the time to divide yet.( If I remember correctly all division process depends on the DNA being connected with the membrane.)In order to have effective protein translocation in bacteria ribosomes must translate on the membrane and since transcription and translation in bacteria is simultaneous the DNA should be attached to the membrane.
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