Adenine (A)

Adenine (A) is a nitrogen-containing base that is one of the four basic building blocks of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Adenine is also referred to as a purine base because of its double-ring structure. In DNA, adenine pairs with thymine through two hydrogen bonds, while in RNA, adenine pairs with uracil through the same two hydrogen bonds.

The chemical formula for adenine is C5H5N5, and its structure consists of a purine ring attached to a ribose sugar molecule in RNA and a deoxyribose sugar molecule in DNA.