DNA molecule. Computer graphic of a view down a portion of beta DNA (deoxyribonucleic acid). Atoms are depicted as balls and sticks and are colour- coded: carbon (white), hydrogen (light blue), nitrogen (dark blue), oxygen (red) and phosphorous (orange). Beta DNA is the more common form, and spirals clockwise when seen from above. The purple line follows the molecule's spiral shape. DNA contains all the inherited instructions necessary to produce an organism. The DNA molecule is formed of two spiral strands of atoms joined by the inte- ractions of cross-linking bases between them. The base sequence on the strands makes up the genetic code in the form of genes, segments of DNA.