Thymine (T) is one of four chemical bases in DNA, the other three being adenine (A), cytosine (C), and guanine (G). Within the DNA molecule, thymine bases located on one strand form chemical bonds with adenine bases on the opposite strand. The sequence of four DNA bases encodes the cell's genetic instructions.


Thymine is one of the building blocks of DNA. It's one of the four nucleotides that are strung together to make the long sequence that you find in DNA, of C, A, Gs, and Ts. It's the T of the C, A, Gs, and Ts. And in the double helix, thymine pairs with adenine, or the A nucleotide.

- Lawrence C. Brody, Ph.D.