JEE Main 2025 Jan 24 Shift 1, Chemistry Q11: Nucleic Acids

JEE Main2025Jan 24, Shift 1Chemistry

The carbohydrates "Ribose" present in DNA, is

A. A pentose sugar

B. present in pyranose from

C. in "D" configuration

D. a reducing sugar, when free

E. in $α$ -anomeric form

Choose the correct answer from the options given below :

Solution

The sugar in DNA is $β$ -2-deoxy-D-ribose. Check each option:

A. It has five carbons $\Rightarrow$ pentose. $✓$

B. In nucleic acids the sugar is locked in the five-membered furanose ring, not pyranose. $\times$

C. It is in the D configuration (the OH on the chiral carbon farthest from the carbonyl is on the right in Fischer projection). $✓$

D. Free deoxyribose carries a hemiacetal at C-1, so it is a reducing sugar (only when not glycosidically linked into the nucleic acid). $✓$

E. The anomer in DNA is $β$ , not $α$ . $\times$

Correct statements: A, C and D. $∴$ Option (1).

Concept behind this question

Concept-wise practice with instant solutions on Fundamenthol.