2004 Nobel Prizes in Physiology & Medicine -     American researchers Richard Axel, of the Howard Hughes Medical Institute and Columbia University and Linda B. Buck, of the Fred Hutchinson Cancer Research Center in Seattle, shared the 2004 Nobel Prize in physiology or medicine for their work on the sense of smell — showing how, for example, a person can smell a lilac in the spring and recall it in the winter. They discovered genes, in 1991, that give rise to a huge variety of “receptor” proteins that sense particular odors. These proteins are found in cells in the nose, which communicate with the brain.       A whiff of an odor brings a mix of different molecules into the nose, where each molecule activates several odor receptors. This pattern of activation is interpreted by the brain, letting people recognize and form memories of about 10,000 different odors.  About 3 percent of human genes are devoted to producing the odor receptors.

2004 Nobel Prizes in Chemistry for "Proteasomes" - for the discovery of ubiquitin mediated protein degradation.  Arron Ciechanover, Avram Hershko, and Irwin Rose. Protein degradation takes place through a controlled process in which proteins are tagged with a label molecule called ubiquitin, which fastens to the protein to be destroyed. The labelled proteins are then fed into a cells' "waste disposers", the so called proteasomes, where they are chopped into small pieces and destroyed.              Animation (Nobel website) »