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JEE Main · 2026 · 23 Jan 2026 · Shift 2 · Biomolecules

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Both human DNA and RNA are chiral molecules. The chirality in DNA and RNA arises due to the presence of
  1. (A)Base unit
  2. (B)Chiral phosphate unit
  3. (C)D-sugar component✓ Correct
  4. (D)L-sugar component

Answer: (C)

Solution

Both nucleic acids are built on a sugar--phosphate backbone whose pentose is D-ribose in RNA and 2-deoxy-D-ribose in DNA. These sugars contain asymmetric carbon atoms, whereas the phosphate linkages and the planar nitrogen bases are not centres of chirality. The optical activity of DNA and RNA therefore arises from the D-sugar component.

JEE Main · 2026 · 23 Jan 2026 · Shift 2 · Single correct option

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