Genetic code. Conceptual computer artwork of a DNA molecule overlaid with a table showing how a genetic sequence encodes a protein sequence. Genetic information is stored as long, complex sequences of the four different bases in DNA (deoxyribonucleic acid). These are adenine (A), thymine (T), guanine (G) and cytosine (C). Triplets (groups of three) of these bases are interpreted by the genetic machinery as instructions to add a certain amino acid (a chemical building block) to a protein. Most amino acids can be encoded as several different triplets. DNA directs the activity of cells, and processes such as growth and development.