Which of the following elements is not found in DNA and RNA?

Correct answer: (c) Sulphur

Explanation

DNA and RNA are made of nucleotides. Each nucleotide has:

• a pentose sugar (deoxyribose or ribose): carbon, hydrogen and oxygen;
• a nitrogenous base (adenine, guanine, cytosine, thymine or uracil): containing nitrogen;
• a phosphate group: phosphorus and oxygen.

So nucleic acids contain C, H, O, N and P, but no sulphur. Sulphur is found in proteins, in the amino acids cysteine and methionine. This difference let Hershey and Chase show in 1952 that DNA, not protein, is the genetic material.