The heterocyclic pyrimidine and purine compounds which are constituents of all nucleic acids. Adenine (
A), guanine (
G) and cytosine (
C) are found in both DNA and RNA, thymine (
T) is found (primarily) in DNA and uracil (
U) only in RNA.
Source:
PAC, 1992, 64, 143. 'Glossary for chemists of terms used in biotechnology (IUPAC Recommendations 1992)' on page 147 (https://doi.org/10.1351/pac199264010143)