DNA (or deoxyribonucleic acid) is the molecule that carries the genetic information in all cellular forms of life and some viruses. It belongs to a class of molecules called the nucleic acids, which are polynucleotides - that is, long chains of nucleotides.
Genes contain the code to make proteins, which are involved in the development and functioning of body organs and systems. Proteins are essential to life and have many functions in the body, for example, as enzymes, regulators and structural molecules. Genes are also the unit of heredity by which characteristics such as eye colour and blood group, and passed from one generation to the next.