Question

A 152nm long Watson Crick double helical DNA (B DNA) will contain ____ turns​

Answer 1

Explanation:

One complete turn of the double helix is 3.4 nm long and each of which has 10 base pairs. A nucleotide is made up of sugar, the nitrogenous base and phosphate moiety and each nucleotide base of one strand is paired in the same plane with a base of the other strand. Therefore, there are total 10 x 2= 20 nucleotides in one complete turn of the double helix which is 3.4 nm long. Hence a DNA strand of 340 nm would have 20/3.4 × 340 = 2000 nucleotides. This makes option A correct. 

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