Question

Nucleotides are monomers of DNA. What does each nucleotide consist of?

• A. A nitrogenous base and a pentose sugar.
• B. A nitrogenous base and a phosphate group.
• C. A pentose sugar and a phosphate group.
• D. A nitrogenous base, a pentose sugar and a phosphate group.

Answer 1

The correct option is D A nitrogenous base, a pentose sugar and a phosphate group.

DNA is polymer of nucleotides which are made up of a pentose sugar, nitrogenous base and phosphate moiety. DNA has four bases; two purines and two pyrimidines. The two purines are namely adenine and guanine and two pyrimidines are cytosine, thymine. The nucleotide units of DNA contain 2’deoxy-D-ribose sugar. A nucleotide unit without phosphate group is called nucleoside. Thus, option D is correct.