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Which DNA bases pair with each other?

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Diagram of a DNA polynucleotide chain showing linked deoxyribose sugars, phosphate groups, and nitrogenous bases (adenine, guanine, cytosine, thymine), with an inset comparing ribose and uracil in RNA. — Nucleic acid A portion of the polynucleotide chain of deoxyribonucleic acid (DNA), with an inset showing the corresponding pentose sugar and pyrimidine base in ribonucleic acid (RNA).

In DNA, the nitrogenous bases pair according to the Watson-Crick model, which is essential for the molecule's double-helical structure. The specific pairing rules are as follows:12

Adenine (A) always pairs with Thymine (T).12
Guanine (G) always pairs with Cytosine (C).12

These pairs are held together by weak hydrogen bonds, which connect the two strands of the DNA molecule. While uracil (U) is a nitrogenous base found in RNA, it is not present in DNA, where it is replaced by thymine. The consistency of these A-T and G-C pairings ensures the stability of the DNA structure and allows the molecule to function as a template for replication, enabling the accurate transmission of genetic information.1324