Genetic information is nucleic acid not protein

Another microbiological experiment was used to determine if DNA alone could be responsible for the persistence of genetic information in a daughter cell. The experiment supposed that labeled DNA would be detectable in all progeny of a cell, and conversely that labeled protein would also persist, if either were the primary informational macromolecule. This sounds simple in theory, but practically bacteriophageswere the only way to manufacture a genetic entity with either DNA labeling only or protein labeling only. Hershey and Chase 32P-radiolabeled T2 bacteriophage DNA, and then allowed the self-assembly of virions with unlabeled protein. Concurrently they 35S-radiolabeled T2 bacteriophage coat protein, and made virions with unlabeled DNA.

By interrupting the infection of E. coli by T2, by using a blender, they were able to separate the heads from the cells through centrifugation. In this way they demonstrated that the DNA entered the cell and caused a change but not the T2 protein, conclusively demonstrating that DNA carries genetic information.