Deoxyribonucleic acid (DNA)

DNA is made up from four different nucleotides (denoted G, A, T or C), each of which consists of one of four bases (guanine, adenine, thymine or cytosine) attached to a sugar, which is linked to a phosphate group. The sugars are strung together via the phosphate groups to form the backbone of long strands. Finally, two strands running in opposite directions twist together to form the familiar double helical structure.

The progression of the four bases along these strands spells the unique traits for each individual (DNA code), and the complete sequence - just over 3 billion items of code - is the genome. It is changes in the DNA code that create the subtle difference between us, and in extreme cases cause genetic diseases, some of which are inherited whilst others occur spontaneously. Ribonucleic acid (RNA) Proteins are not made directly from DNA. An edited copy of the DNA code is first reproduced in ribonucleic acid (RNA). The process of making this edited copy is called transcription and RNA acts as the intermediate - the interpreter in the conversation between DNA and the rest of the cell.

Strings of twenty distinct amino acids make up the complex molecules called proteins; the chemical composition of which causes sections to attract or repel one another and in doing so create the unique three-dimensional structures.