DNA (Deoxyribonucleic acid) is a biological molecule that contains the genetic information that determines how organic cells form and operate. It is a nucleid acid, a macromolecule, that is usually a double stranded helix form. This consists of two biopolymers constructed of nucleotides, that are themselves composed of nucleobases. These are of four types, guanine, adenine, thymine and cytosinem, each also having an either phosphate or sugar (deoxyribose) backbone. DNA is packed in to chromosomes and therefore plays an important role in genetics and genetic heredity.