Question

How do purines compare to pyrimidines?

Answer 1

Pyrimidines contain one ring, while purines contain two rings fused together.

Pyrimidines

Pyrimidine is an aromatic heterocyclic compound similar to pyridine.

A chemist would call it 1,3-diazine (2 `"N"` atoms in an unsaturated 6-membered ring).

Three of the bases in nucleic acids (cytosine, thymine, and uracil) are pyrimidine derivatives.

Purines

A purine is a heterocyclic aromatic compound consisting of a pyrimidine ring fused to an imidazole (1,3-diazole) ring.

(from www.boundless.com)

Two of the bases in nucleic acids (adenine and guanine) are purines.

Purine-Pyrimidine Base Pairing

Purines and pyrimidines have one crucial property: a purine in one strand of DNA can form hydrogen bonds to a pyrimidine in the other strand..

The A-T and C-G base pairing holds the strands of DNA together.