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JEE Main · 2021 · 27 Jul 2021 · Shift 1 · Biomolecules

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The compound 'A' is a complementary base of ______ in DNA strands.
  1. (A)Adenine✓ Correct
  2. (B)Cytosine
  3. (C)Guanine
  4. (D)Uracil

Answer: (A)

Solution

The structure is a pyrimidine ring bearing two carbonyl groups and a methyl group at position , that is -methyluracil, which is thymine. In the DNA double helix the two strands are held by hydrogen bonds between a purine and a pyrimidine: thymine pairs with adenine through two hydrogen bonds and cytosine pairs with guanine through three. Uracil replaces thymine in RNA and is not a DNA base at all. The complementary base of this compound in DNA is adenine.

JEE Main · 2021 · 27 Jul 2021 · Shift 1 · Single correct option

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