DNA -- Deoxyribonucleic acid. The genetic material of all cells and many viruses. A polymer of nucleotides. The monomer consists of phosphorylated 2 deoxyribose N glycosidically linked to one of four bases adenine, cytosine, guanine or thymine. These are linked together by 3',5' phosphodiester bridges. In the Watson Crick double helix model two complementary strands are wound in a right handed helix and held together by hydrogen bonds between complementary base pairs. The sequence of bases encodes genetic information. Three major conformations exist A DNA, B DNA that corresponds to the original Watson Crick model) and Z DNA.