JEE Main · 2021 · Shift-ImediumBIO-151

Out of following isomeric forms of uracil, which one is present in RNA?

Biomolecules · Class 12 · JEE Main Previous Year Question

Question

Out of following isomeric forms of uracil, which one is present in RNA? image image

Options
  1. a

    Option a

  2. b

    Option b

  3. c

    Option c

  4. d

    Option d

Correct Answerc

Option c

Detailed Solution

Step 1: Uracil Tautomerism — Like all nitrogenous bases, Uracil exists in tautomeric forms (amide/enol).

Step 2: Most Stable Form — In physiological conditions (pH 7), the diketoform is the dominant and most stable isomer.

Step 3: Identification — This structure involves two carbonyl (\ceC=O)(\ce{C=O}) groups at the C2 and C4 positions. Correct option is (c).

Key Point: The keto form correctly positions the hydrogen-bond donors and acceptors for base-pairing.

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