Question

Which criteria from the list can be used to discriminate between purine and pyrimidine nucleotides?

A. The number of hydrogen bonds they can form
B. Their sugar-phosphate backbone structure
C. The presence of adenine or guanine
D. The presence of thymine or cytosine

Answer 1

The presence of adenine or guanine indicates a purine nucleotide, while the presence of thymine or cytosine indicates a pyrimidine nucleotide. Purines have a double-ring structure and pyrimidines have a single-ring.

Step-by-step explanation:

The criteria that can be used to discriminate between purine and pyrimidine nucleotides are based on the structure of their nitrogenous bases. Purines, such as adenine (A) and guanine (G), are characterized by a double-ring structure, whereas pyrimidines, such as cytosine (C) and thymine (T), have a single-ring structure.

The correct criteria from the list are therefore:

• The presence of adenine or guanine, which would indicate a purine nucleotide.
• The presence of thymine or cytosine, which would indicate a pyrimidine nucleotide.

The number of hydrogen bonds each can form is a result of this distinction since A and T form two hydrogen bonds and C and G form three. However, the sugar-phosphate backbone structure is not a distinguishing factor since it is common to all nucleotides.