Adenine (A) is one of four chemical bases in DNA, with the other three being cytosine (C), guanine (G), and thymine (T). Within the DNA molecule, adenine bases located on one strand form chemical bonds with thymine bases on the opposite strand. The sequence of four DNA bases encodes the cell's genetic instructions. A form of adenine called adenosine triphosphate (ATP) serves as an energy storage molecule and is used to power many chemical reactions within the cell.


Adenine is one of the four building blocks of DNA. It's the A of the A, C, G, and T that's in DNA. Adenine has the property that, when it's in the double helix, it is always found opposite of thymine, so adenine and thymine pair one on each strand. Adenine is also used elsewhere in the cell, not just in DNA and RNA, but it's part of the molecule adenosine triphosphate, which is the energy source for the cell. So adenine plays a dual role in the cell: it's used for building DNA and RNA, but it's also used at storing energy in the cell.

- Lawrence C. Brody, Ph.D.