Genetics relies on chemistry to explain field-related phenomena. The structure of DNA is based on chemistry. In fact, when James Watson and Francis Crick discovered the structure of DNA, they did so by building models based on the laws of chemistry. Chemistry is also closely linked to the structure and function of one of the main products of DNA: proteins. Chemistry determines the structure of DNA. DNA is a polymer of monomers called nucleic acids. These consist of a nitrogenous base, a phosphate group and a sugar. It is the negative charge on the phosphate group that makes DNA an acid. There are 4 different bases: adenine, thymine, guanine and cytosine. In groups of three, these four bases can encode any protein encoded in an organism's genome. Two strands of nucleic acids stack on top of each other to form a double helix. The backbone of nucleic acids is formed by the interaction between the phosphate groups and hydroxide groups of nucleic acids. These are held together by covalent bonds called phosphodiester bonds. The helix itself is held together by hydrogen bonds. Although h...