Question

Select the correct answer from the following for DNA can be

1. A-DNA
2. B-DNA
3. Z-DNA
4. Y-DNA

• A. 1, 2 and 3 correct
• B. 1 and 2 correct
• C. 2 and 4 correct
• D. 1 and 3 correct

Answer 1

The correct option is A 1, 2 and 3 correct

DNA has double helical structure where the two strands are tightly coiled over each other.

A-DNA has right handed helix with major and minor groove. The diameter of the DNA is 26 A${}^o$. The number of base pairs in one turn is 11 and the distance between base pairs is 2.55 A${}^o$. So the total length of one turn of DNA is 10* 3.4 = 34 A${}^o$.

B- DNA has right handed helix with major and minor groove. The diameter of the DNA is 20 A${}^o$. The number of base pairs in one turn is 10 and the distance between base pairs is 3.4 A${}^o$. So the total lenght of one turn of DNA is 28 A${}^o$.

Z- DNA has left handed helix with major and minor groove. The diameter of the DNA is 18 A${}^o$. The number of base pairs in one turn is 12 and the distance between base pairs is 7.4 A${}^o$. So the total length of one turn of DNA is 44 A${}^o$.

So, the correct answer is option A.