Caption

DNA molecule. Computer artwork of a molecule of DNA (deoxyribonucleic acid). DNA is composed of two strands (silver, outside) twisted into a double helix. Each strand consists of a sugar- phosphate backbone attached to nucleotide bases (blue spheres). There are four bases: adenine, cytosine, guanine and thymine. The bases are joined together by hydrogen bonds (silver, between spheres). DNA contains sections called genes that encode the body's genetic information.