Question

Consider the following structures

Identify I and II in the above structure and mark the correct option.

• A. I - Nucleotide; II - Nucleotide
• B. I - Nucleotide; II - Nucleosite
• C. I - Nucleoside; II - Nucleotide
• D. I - Nucleoside; II - Nucleoside

Answer 1

Answer: (C)

A unit formed by the attachment of a base to $1^{\prime }$ position of sugar is known as nucleoside. In nucleosides the sugar carbons are numbered as $1^{\prime },2^{\prime },3^{\prime }$ etc., in order to distinguish these from the bases. When nucleoside is linked to phosphoric acid at $5^{\prime }$-position of sugar moiety, we get a nucleotide.