The chemical building blocks of nucleic acid are called nucleotides, and every nucleotide contains a nitrogenous base. The bases can be viewed as the most significant components of nucleic acids such as DNA and RNA, as they are the only variant elements in these otherwise monotonously repeating polymers. Consequently, it is the arrangement of bases along DNA strands that contains the genetic information coding for proteins. This is transcribed into the complementary base sequence in RNA and translated into the amino acid sequences of the protein chains, with three bases specifying a single amino acid. Thus the coding potential of the nucleic acid bases is arranged as a triplet code.

The bases are classified as purines and pyrimidines. Purines are two ring shaped molecules joined together, one with six and one with five atoms, while pyrimidines are single rings of six atoms. DNA is made up of nucleotides...