DNA (desoxyribonucleic acid) stores the genetic information of a cell and hence constitutes the material of which genes are made. The DNA molecule consists of a sugar phosphate backbone and four different bases: adenine, thymine, cytosine and guanine (A, T, C and G).
The scientists James Watson and Francis Crick discovered the structure of DNA in the form of a double helix in 1953.
This can be imagined as a long rope ladder twisted into a spiral shape; the sides of the ladder always consist of alternating sugar and phosphate residues, while the "rungs" (made up of the four bases) are firmly attached to the ladder. The sequence of three bases forms the genetic code for an amino acid.