In 2004, Buck won the Nobel Prize in physiology or medicine for her research on the sense of smell. She shared her Nobel Prize with Richard Axel. The two scientists made many new discoveries about Genetic and cellular Mechanisms responsible of the sense of smell in human beings and other organisms. In a series of experiments Buck (working independently from Axel) discovered how people separate different smells in their nose. She learned that people detect smells from odor in the air. Odors are released through many different substances. These molecules stimulate olfactory response cells in the nose. They send signals to the brain. Buck discovered that there are 350 smell receptors in the nose.