The DNA synthesis phase

Genetics as it applies to evolution, molecular biology, and medical aspects.

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teenager witch
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The DNA synthesis phase

Post by teenager witch » Wed Jan 09, 2008 1:03 pm

Hello..how are you everybody? :)
When the cell has the whole group of chromosomes, we say it is (2n) and when it has half the group of chromosomes, it is(n).The question is when the human cell is in the DNA synthesis phase would be right to say that the cell is (4n) and has 92 chromosomes or we can't?
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mith
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Post by mith » Wed Jan 09, 2008 5:46 pm

I think the n number only refers to unique chromosomes so even though there is twice the amount, they're copies so you still only have 2n. However another number "c" measures mass of chromosomes. You would have a 2n 4c cell.
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teenager witch
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Post by teenager witch » Thu Jan 10, 2008 7:59 am

I believe the same....thank you for your reply.
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MrMistery
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Post by MrMistery » Thu Jan 10, 2008 6:16 pm

i have heard the term "tetraploid" used for a cell which has replicated its DNA... I don't see why it is not correct.
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Re: The DNA synthesis phase

Post by Darby » Fri Jan 11, 2008 12:38 am

It's purely a convention to consider double-stranded chromosomes to still be only single chromosomes.

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MrMistery
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Post by MrMistery » Fri Jan 11, 2008 7:03 pm

to be fully accurate, the books i studied said: "although the cell is still diploid from the point of view of chromosome number it is tetraploid from the point of view of DNA molecules"
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