cytosine By Ivan Suarez Robles 14 Nov, 2010 One of the four nitrogenous bases found in DNA; pairs with the base guanine; often abbreviated as the letter ‘C’Related Articles: NPR's This American LifeGlossary: mismatch repair enzymeGlossary: mithramycinAll About MutationsAn Introduction to DNA and Chromosomes (Text and Audio)