1912-

German-born American biochemist who received the 1964 Nobel Prize for physiology or medicine, shared with Feodor Lynen, for research into the metabolism of cholesterol and fatty acids. Early in his scientific studies Bloch found that acetic acid is a major precursor to cholesterol, a molecule that has 27 carbons in its base. Cholesterol, an essential compound in all animal cells, is necessary for the formation of bile and hormones, such as cortisone and the sex hormones. Using radioactive carbon-14, Block traced the process through which acetic acid is transformed by the body into cholesterol.