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DNA = Chromosome

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

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DNA = Chromosome

Postby ssas » Fri Aug 18, 2006 2:23 pm

One molecule of DNA equals one whole piece of chromosome.
Then in human cell, we have altogether 46 molecules of DNA per cell.
Is this right or not?
Could anyone clarify this for me. thank you.
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Postby LilKim » Fri Aug 18, 2006 3:18 pm

Many molecules comprise individual genes (some genes are big and others are smaller).

Genes reside at specific location on chromosome. SO; essentially each chromosome contanis a collection of genes.. (of course each gene has different number of molecules... so, each chromome has a different molecular weight).

So, yes, we have 46 chromosomes... but we have a SIGNIFICANTLY greater number of molecules that chromosomes.

Anyways, i'm too lazy to look up the number of nucleotides in the genome... but that would be the first step in determining how many molecules each cell contians.

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Postby ssas » Fri Aug 18, 2006 5:12 pm

Thank you so much for your prompt reply, LilKim.
But I think what you are talking about is "nucleotide" which is the simpliest subunit in the whole chains of DNA, or in other words the "Base pair".
Yes, one gene does contain thousands of nucleotides or base pairs. But what I am really confused is that "Does one whole molecule of DNA (which is supposed to contain thousands of nucleotides) equal to one whole piece of chromosome (which we have 46 in a cell)?"
Thank you for your comments
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Postby canalon » Fri Aug 18, 2006 6:21 pm

Sorry Kim but I think you misunderstood the question. How many DNA molecules per cell?
Twice as much as chromosome is the good answer because 1 chromosome = 1double helix= 2 DNA molecules bonded by Hydrogene bonds.
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Postby LilKim » Mon Aug 21, 2006 8:48 pm

thanks for the correction canalon!
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Postby weesper » Wed Aug 23, 2006 6:22 am

Canalon wrote:Sorry Kim but I think you misunderstood the question. How many DNA molecules per cell?
Twice as much as chromosome is the good answer because 1 chromosome = 1double helix= 2 DNA molecules bonded by Hydrogene bonds.


Exactly Canalon is right and Lil Kim is wrong; chromosome 1 is the largest molecule in our cells, the fact that a chromosome consists of many nucleotides does not distract from the fact that altogether they form one molecule. So yes in total 46 molecules.

To Lil Kim, the total (textbook) number of nucleotides in the human genome is about 3 000 000 000.
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Postby canalon » Wed Aug 23, 2006 2:14 pm

weesper wrote:Exactly Canalon is right and Lil Kim is wrong; [...] So yes in total 46 molecules.


I like to hear that :P

But, however much I hate to correct people, YOU too are wrong, and did not read my answer.
1 chromosome = 2 DNA molecules
23 pairs of chromosomes = 46 chromosomes = 92 DNA molecules
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Postby yumna_ghazi » Wed Aug 23, 2006 4:16 pm

Although I have just stepped into the world of biology, still I think I will Inshallah be able to clarify u.
I am not sure whether One molecule of DNA equals one whole piece of chromosome.
DNAs are in the nucleus of a cell. And each cell has more than one chromosome. So I think your deduction is incorrect.
Try this site:
http://www.thetech.org/exhibits_events/ ... rview.html
It tells the very basics of DNA.... Maybe u could find the answer there.
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Postby MrMistery » Wed Aug 23, 2006 5:57 pm

sorry yumna_ghazi but Canalon is right. The DNA double helix consists of 2 molecules, because hydrogen bonds are intermolecular bonds.
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Postby LilKim » Wed Aug 23, 2006 5:58 pm

yumna_ghazi wrote:Although I have just stepped into the world of biology, still I think I will Inshallah be able to clarify u.
I am not sure whether One molecule of DNA equals one whole piece of chromosome.
DNAs are in the nucleus of a cell. And each cell has more than one chromosome. So I think your deduction is incorrect.
Try this site:
http://www.thetech.org/exhibits_events/ ... rview.html
It tells the very basics of DNA.... Maybe u could find the answer there.


Hey There! And welcome to the world of biology!!!

When I read the initial question i misinterpreted it... and I kinda threw-everyone off...

Anyways, after Canalon pointed out my error... I realized. And, I agree 100% with his explanation. (in reference to the initial question asked)

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Postby yumna_ghazi » Fri Aug 25, 2006 11:50 am

Thanx for the correction guyz! I just wanted to kinda mix up with u senior people!
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Postby weesper » Fri Aug 25, 2006 9:33 pm

MrMistery wrote:sorry yumna_ghazi but Canalon is right. The DNA double helix consists of 2 molecules, because hydrogen bonds are intermolecular bonds.


Damn thanx for pointing this out, and Canalon thanks for proving me wrong I just never stopped to think that the hydrogen bonds maintain an inter!molecular bond.
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