-DNA, or deoxyribonucleic acid, is a long chain molecule that plays a central role in life on earth. The information encoded in strands of DNA controls the genetic makeup of organisms. The DNA molecule has a backbone of sugars and phosphate groups off of which hang simpler units called nucleotide bases. DNA contains only four bases, called A, T, C and G. The sequence of the nucleotides along the backbone encodes genetic information.