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.