Definition: A nitrogen-containing, single-ring, basic compound (cf. nitrogenous base) that occurs in nucleic acids.
The pyrimidines in DNA are cytosine and thymine. The pyrimidines in RNA are cytosine and uracil.
See also
nucleic acid synthesis
pyrimidine pathways
References
Loffler M, Fairbanks LD, Zameitat E, Marinaki AM, Simmonds HA. Pyrimidine pathways in health and disease. Trends Mol Med. 2005 Aug 9; PMID: #16098809#