Alfred Hershey and Martha Chase (1952) experimentally proved that DNA is the sole genetic material in bacteriophage. On the other hand, Beadle and Tatum (1940s) experimentally showed one gene-one enzyme hypothesis using Neurospora. Meselson and Stahl first showed that DNA replicates semiconservatively through experiments on E.coli. Jacob and Monod were first to explain lac operon.