DNA sequence. Computer screen display showing the colour-coded peaks of spectra showing genetic sequences. The peaks correspond to the nucleotide bases in a DNA (deoxyribonucleic acid) sample. The precise sequence of the bases forms a genetic code that is unique for every individual. DNA controls the development and functioning of every living organism. The sequence of letters below the peaks are also colour-coded, and match the four bases found in DNA: adenine (A), thymine (T), cytosine (C) and guanine (G, not seen).