DNA. Computer artwork of part of a DNA molecule forming a question mark. In the background is an autoradiogram. DNA (deoxyribonucleic acid) is the molecule which controls the growth and development of all living things. It comprises two helical sugar-phosphate strands (yellow) linked by pairs of bases (red, green, yellow, blue). The sequence of base pairs forms the genetic code. The dark bands on an autoradiogram allow researchers to determine the sequence of DNA bases. Each individual has a slightly different base sequence, and autoradiograms are used in forensic science, genealogy and medical research.