The discovery of the double helix, the twisted-ladder structure of deoxyribonucleic acid (DNA), by James Watson and Francis Crick in 1953 marked a milestone in the history of science and gave rise to modern molecular biology, which is largely concerned with understanding how genes control the chemical processes within cells.

Today we know that DNA is an organic chemical that contains genetic information and instructions for protein synthesis, while simultaneously possessing the power to control the biochemical activities of cells. It is found in most cells of every organism. DNA is a key part of reproduction in which genetic heredity occurs through the passing down of DNA from parent or parents to offspring.