Born 1938. An American molecular biologist and virologist who won the Nobel Prize in 1975 for discovering that retroviruses (a group of viruses that uses RNA to code their genomes instead of DNA) make the enzyme "reverse transcriptase," which is used to make DNA copies of RNA templates. This is useful to the retrovirus who is trying to reproduce with host cellular machinery. More important, this is very useful to molecular biologists and genetic engineers who want to work with RNA molecules using DNA-manipulating techniques.