Walter Gilbert developed a method for determining the sequence of bases (individual components) in DNA, for which he shared the 1980 Nobel Prize in chemistry with Frederick Sanger and Paul Berg. Gilbert was born in Boston, Massachusetts, to a psychologist mother and an economist father. Interested in science since childhood, he majored in chemistry and physics at Harvard and received his Ph.D. from Cambridge University in England in 1957 for work in mathematical physics.

While teaching at Harvard, Gilbert shifted to experimental biophysics through acquaintanceship with James Watson, co-discoverer of the double helix shape of DNA. They experimented with messenger RNA, the nucleic acid that carries gene information to a cell's ribosomes for protein production.

In 1965-66 Gilbert and Benno Muller-Hill explored what mechanisms a cell employs to turn genes "on" or "off." Using a radioactive tracing technique, they isolated a protein which turns off production of lactose-digesting enzymes...