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  #1  
Old 07-12-2011
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DNA DNA base percentages

A nucleic acid was analyzed and found to contain 32% adenine, 18% guanine, 17% cytosine and 33% thymine. The nucleic acid must be ?
A) Single-stranded RNA B) Single-stranded DNA C) Double-stranded RNA D) Double-stranded DNA
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  #2  
Old 07-12-2011
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bbbbbbbbbbbbbbbbb
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Quote:
Originally Posted by saintdizzy View Post
A nucleic acid was analyzed and found to contain 32% adenine, 18% guanine, 17% cytosine and 33% thymine. The nucleic acid must be ?
A) Single-stranded RNA B) Single-stranded DNA C) Double-stranded RNA D) Double-stranded DNA
I also think is B)

Since we have thymine...A) and C) are incorrect
Now, in order to be a ds-DNA we will need:
32% adenine, 18% guanine, 18% cytosine and 32% thymine
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Originally Posted by bebix View Post
I also think is B)

Since we have thymine...A) and C) are incorrect
Now, in order to be a ds-DNA we will need:
32% adenine, 18% guanine, 18% cytosine and 32% thymine
bebix u mean ss-DNA?
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Originally Posted by saintdizzy View Post
bebix u mean ss-DNA?
not...ds-DNA
32% adenine, 18% guanine, 18% cytosine and 32% thymine

Chargaff Parity Rule
The first rule holds that a double-stranded DNA molecule globally has percentage base pair equality: %A = %T and %G = %C
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I think is B ... SS-DNA
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Correct Answer Answer is D

The answer is D
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Quote:
Originally Posted by saintdizzy View Post
The answer is D
Could you explain please?
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Old 07-12-2011
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Originally Posted by rulz View Post
Could you explain please?
Chargaff's rule. bebix mentioned it earlier. I got the question from a website and this was the answer they gave. their explanation being that chargaff's rule applies for ds-DNA. it might be wrong, so it is open for discussion.
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Quote:
Originally Posted by saintdizzy View Post
Chargaff's rule. bebix mentioned it earlier. I got the question from a website and this was the answer they gave. their explanation being that chargaff's rule applies for ds-DNA. it might be wrong, so it is open for discussion.
ok, but am i missing something ? because as bebix said, the Chargaff rules says that DS DNa A= T / G =C has to be equally and in this question shows un-Equal base...

So Answer is B Single Stranded DNA ....
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Originally Posted by rulz View Post
ok, but am i missing something ? because as bebix said, the Chargaff rules says that DS DNa A= T / G =C has to be equally and in this question shows un-Equal base...

So Answer is B Single Stranded DNA ....
Well i need to contact the owners of the website then, its a website for medical council of india exams, so i just share questions from there that are usmle related. Thanks for pointing out the mistake
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Originally Posted by rulz View Post
ok, but am i missing something ? because as bebix said, the Chargaff rules says that DS DNa A= T / G =C has to be equally and in this question shows un-Equal base...

So Answer is B Single Stranded DNA ....
yup, thatīs why I also think is B)...for a ds-DNA we will need:
32% adenine, 18% guanine, 18% cytosine and 32% thymine

and here we have...
32% adenine, 18% guanine, 17% cytosine and 33% thymine...
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