Scientific Contribution

In 1952, Hershey and Chase provided evidence that DNA was genetic material with the results from their phage experiment (Griffiths et al. 2012). They began their experiment by infecting two separate Escherichia coli (E. coli) cultures with many virus particles per cell (Griffiths et al. 2012). One set of bacteriophages had a protein coat labeled with radioactive sulfur; a component that is present in proteins but never DNA. The other set had DNA labeled with radioactive phosphorous; an integral component of DNA that is absent from the building blocks of proteins. They allowed infection to occur after inoculation with E. coli, then agitated the empty phage carcasses off the bacterial cells via a kitchen blender. This is why the experiment is often referred to as the 'blender experiment'. After the separation of the bacterial cells from the phage carcasses via centrifuge, they measured the radioactivity (Griffiths et al. 2012). 

Their experiment concluded that when the phosphorous-labeled phages were used to infect E. coli cells, radioactivity was found inside the bacterial cells (Griffiths et al. 2012). This indicated that the phage DNA entered the cells. In contrast, when the sulfur-labeled phages were used, the radioactive material was found in the phage carcasses, which meant that the phage protein never entered the cells (Griffiths et al. 2012). This meant that DNA was indeed the genetic material as the phage proteins acted to deliver the infected DNA to the bacterial cells.