George Wells Beadle was an American scientist in the field of genetics. He shared half of the 1958 Nobel Prize in Physiology or Medicine with Edward Lawrie Tatum for their discovery that genes act by regulating biochemical events within the cell. The other half of that year’s award went to Joshua Lederberg.
Beadle and Tatum’s key experiments involved exposing the bread mold Neurospora crassa to x-rays, causing mutations. In a series of experiments, they showed that these mutations caused changes in specific enzymes involved in metabolic pathways. These experiments led them to propose a direct link between genes and enzymatic reactions, known as the "one gene, one enzyme" hypothesis.