How does DNA base pairing work?

Cytosine and Thymine are pyrimidines, while Adenine and Guanine are purines.

Watson and Crick base pairs, which are determined by particular hydrogen bonding patterns, enable the DNA helix to retain its regular helical structure.

Adenine and Thymine have two sites where they form H-bonds, while Cytosine and Guanine have three. The structure and characteristics of these bases determine which purine and which pyrimidine pair together.

These base pairs are joined to form the double helix or ladder of DNA.

In order for the four nitrogenous bases to properly attach, stabilize, and bond to the sugar-phosphate backbone of DNA, a particular tautomeric form needs to be included.

DNA base pairing involves complementary pairing between the nitrogenous bases of two DNA strands. Adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). This pairing occurs through hydrogen bonds, forming a stable double-stranded DNA structure.