Hershey and Chase showed that phages only injected their DNA into host bacteria, and that the DNA served as the replicating genetic element of phages. These scientists wanted to know what exactly was being reproduced, whether it was DNA or proteins. In this way, they made two groups of bacteriophages, the first had radioactively labeled DNA (with phosphorus-> P-32) and the second group the proteins (with sulfur-> S-35).
Once done, they placed these marked bacteriophages on a petri dish waiting for their reproduction. It was here that they were able to observe that bacteriophages that had phosphorus-labeled DNA, their agents had acted on it, and the offspring still had radioactivity.
The result as seen in the photograph is that the agent that multiplies is NOT the proteins but yes the DNA.
