DNA has been discovered by the young Swiss doctor Miesscher in 1868. Miesscher was doing experiments on pus cells from hospital bandages and discovered a sort of white precipitate, coming from the nucleus of the cells. He called it nucleine. Later this substance was found to have acidic properties and it was called nucleic acid. That is why DNA is the abbreviation of DeoxyriboNucleicAcid. After this discoverey a lot more became known about DNA. It became clear that it was very large molecule. In 1944 it was determined that genetic properties are coded into DNA. So DNA contains information for properties like eyecolor, bloodgroup and for plants for instance information for the color of its flowers. But it was not known exactly how this was coded into the DNA and how this was copied at every cell division. The solution appeared to be in the structure of the DNA. After 1940 a lot of researchers became interested in the DNA and tried to investigate what the structure of the molecule looked like. Like the young American James Watson, who worked at the laboratory of the University of Cambridge with the older researcher Francis Crick. They knew that genes were the keys of all living cells, but therefore they had to investigate how these genes worked. The chemical building blocks of DNA were already known at that time, all they had to find out was how these blocks formed the structure of the molecule. The pair Watson and Crick decided to build models of the molecule, untill the blocks fit into each other. From the X-ray picture of their collegue Rosalin Franklin they knew that DNA had a spiral structure. Eventually they built a model of 2 chains and put the blocks at the right positions. The model had the structure of a twisted rope ladder. Watson and Crick discovered that the DNA molecule is the foundation of the genetic properties and that it is some sort of copy machine. The results of this research got the pair a Nobel prize in 1962   Read the offical article of Watson and Crick: