DNA molecule. Computer representation of a segment of the molecule Deoxyribonucleic Acid (DNA). This structure contains all the inherited instructions necessary for the development of a living organ- ism. Here, colour-coded ribbons and bars depict the structure of the molecule. DNA is composed of two strands twisted into a helical shape, each strand consisting of an outer sugar-phosphate backbone (pink, red). Projecting inward from this backbone are bases (multicoloured) which pair up in a complementary fashion to form a code of instructions. Sixteen base pair units are repre- sented here. Genetic information is determined by the arrangement of base pairs along the molecule.