DNA molecule. Computer artwork of a strand of beta DNA (deoxyribonucleic acid). Atoms are depicted as spheres and are colour-coded: carbon (blue), oxygen (yellow), hydrogen (white), nitrogen (magenta) and phosphorous (orange). Beta DNA is the more common form, and spirals clockwise when seen from above. DNA contains all the inherited instructions necessary to produce an organism. The DNA molecule is composed of two spiral strands of atoms joined by the interactions of cross-linking bases between them. The sequence of bases along the strands makes up the genetic code in the form of genes, specific segments of DNA.