Hershey and Chase were able to label the protein in phages with 35S and the DNA with P32. The transfer of genetic material went with the 32P, showing that the DNA was the genetic material, not the protein. They chose phage because the protein and the DNA are so well separated during infection, allowing a clear answer about the identity of the genetic material.
Work Step by Step
Please review the Hershey and Chase experiment in Ch. 16. You will see that the two radioactive labels were separate, and you can see in Fig. 19.3 how this is physically accomplished. The radiolabels allowed them to observe what material, protein or DNA, appeared in the descendants of the bacteriophages.