Through a series of experiments the duo conducted in 1952, Alfred Hershey and Martha Chase discovered that genetic material is found in DNA. Prior to their discovery, most scientists believed that genetic material was found in proteins due to their diversity and prevalence in cells.
In their experiments, Hershey and Chase injected chemical tracers that resembled proteins and DNA into a type of rapidly reproducing virus called T2. They then tracked the course of the tracers as they made their way through reproduction and found that the tracers that resembled DNA were much more likely than the tracers that resembled proteins to be found in future generations of the cells. Hershey and Chase concluded that DNA, and not protein, was associated with genetic material.