Woman and DNA (deoxyribonucleic acid). Computer illustration of a DNA molecule behind a female figure. A molecule of DNA consists of two strands of sugar phosphates forming a double helix (spiral). The strands are linked by nucleotide bases (vertical struts). There are four types of nucleotide base in DNA. The sequence of the bases in the molecule is the genetic code. The genetic code carried in DNA controls growth and development, and it is passed on during reproduction. DNA is found in all living things, and is stored in cell nuclei.