Question

In both DNA and RNA, heterocyclic base and phosphate ester linkages are at 

• (A) $C-5^{\prime }$ and $C-1^{\prime }$ respectively of the sugar molecule
• (B) $C-1^{\prime }$ and $C-5^{\prime }$ respectively of the sugar molecule
• (C) $C-2^{\prime }$ and $C-5^{\prime }$ respectively of the sugar molecule
• (D) $C-5^{\prime }$ and $C-2^{\prime }$ respectively of the sugar molecule

Answer 1

The Correct Option is B

Explanation:
In DNA and RNA heterocyclic base and phosphate ester are at $C-1^{\prime }$ and $C-5^{\prime }$ respectively of the sugar molecule.

Hence, the correct option is (B).

Answer 2

Phosphate ester linkage is the covalent bond that will connect the sugar molecules with the backbone. This linkage occurs between 3’ carbon of one sugar to the 5’ carbon of the adjacent carbon. The phosphate will provide a negative charge and maintain the stability. 

On the other hand, the heterocyclic base is attached to the Carbon-1’ of both DNA and RNA sugar molecules. The bases present in them are adenine, guanine, cytosine, uracil and thymine.