Question

If the B - DNA carries 100 Guanine bases & length is ,85 nm then how many Adenine present in it ?
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Answer 1

Answer:

55600

Explanation:

A number of nucleotides present in one strand of DNA molecule of 85 Å are 85/3.4 = 25, out of which 20 are Adenine. An equal number of thymine must be present too, which forms a double bond with Adenine. While rest 5 nucleotides in one strand are either guanine or cytosine forming a base pair by a triple bond with another guanine/ cytosine from another strand. So, the total number of hydrogen bonds present are 20×2 + 5×3 = 65.

The two-carbon nitrogen ring bases (adenine and guanine) are purines, while the one-carbon nitrogen ring bases (thymine and cytosine) are pyrimidines. Hence, 20+20+5+5 = 50 C - N rings are present.

So, the correct option in '65, 50'.