What contributions did Hershey and Chase make to the understanding of DNA?

They defined that DNA (not proteins) were responsible for transformation of (thus, genetic infomation)

In their experiment, they labeled a virus capsid (protein part of the virus) with a radioactive isotope (35S). They have also labeled the DNA of another virus with another radioactive isotope (32P). When they used these separetely to infect bacterial cells, they observed that the bacteria that were infected with the labelled DNA remained radioactive, whereas those infected with the labelled protein were not radioactive any longer, and not transformed.