Marshall Warren Nirenberg (1927-2010), US biochemist, performing an experiment. The experiment is related to protein synthesis and genetic code translation. Nirenberg trained as a biologist, but developed an interest in biochemistry and obtained his PhD in that area in 1957. He worked on enzymes, and from 1959 studied the enzymes involved in DNA and RNA (the genetic molecules). From 1962 he was head of Biochemical Genetics at the US National Institutes of Health. He shared the 1968 Nobel Prize in Physiology or Medicine for his work on genetics. Photographed circa 1962.