Paul Berg made one of the most fundamental technical contributions to the field of genetics in the twentieth century: he developed a technique for splicing together deoxyribonucleic acid (DNA)--the substance that carries the genetic information in living cells and viruses from generation to generation--from different types of organisms. His achievement gave scientists a priceless tool for studying the structure of viral chromosomes and the biochemical basis of human genetic diseases. It also let researchers turn simple organisms into chemical factories that churn out valuable medical drugs. In 1980 he was awarded the Nobel Prize in chemistry for pioneering this procedure, now referred to as recombinant DNA technology.

Today, the commercial application of Berg's work underlies a large and growing industry dedicated to manufacturing drugs and other chemicals. Moreover, the ability to recombine pieces of DNA and transfer them into cells is the basis of an important new medical...