Deoxyribonucleic acid (dna) is the complex organic molecular structure that is responsible for encoding information that passes on genetically inherited traits in living creatures. DNA is part of all eukaryotic and prokaryotic cells, in addition to a number of viruses. Although the presence of DNA had been detected in the middle of the 19th century, it was not until 1953 that the Nobel Prizewinning scientists Francis Crick and James Watson determined the characteristic double helix spiral of DNA. DNA strands consist of a chain of nucleotides, which are composed of a sugar molecule (deoxyribose) attached to which are nitrogenous bases known as pyrimidines and purines, as well as a phosphate attachment. The strands are bound to each other covalently and according to a complex, but ...