What Are the Pyrimidine Bases of DNA?

What Are the Pyrimidine Bases of DNA?

The pyrimidine bases of DNA are cytosine and thymine. One pyrimidine combines with one purine to make up a rung of the DNA double helix. Nucleotides, the building blocks of DNA, comprise a phosphate group, a five-carbon sugar and either or a purine or a pyrimidine.

Purines have a double ring, whereas pyrimidines have only a single ring. Each pyrimidine structure is so specific that it only binds with one type of purine. To illustrate, cytosine and guanine pair up, whereas thymine forms a pair with adenine. Purines do not pair with one another, and pyrimidines do not pair with one another. The pairing of a purine only with a pyrimidine is essential because it keeps the width of the DNA molecule consistent.