born Dec. 8, 1947, Chicago, Ill., U.S.
U.S. biochemist, molecular biologist, and Nobel laureate.
He received his Ph.D. from UC-Berkeley in 1975. In 1982 he became the first to show that an RNA molecule could catalyze a chemical reaction. He and Sidney Altman were awarded a 1989 Nobel Prize for their independent discoveries that RNA, previously thought to be only a messenger of genetic information, can also catalyze cellular chemical reactions essential to life.