The Hershey and Chase Experiment

Although Avery's experiments demonstrated that DNA alone could transmit genetic information, there was still some nagging doubt that DNA had sufficient informational potential to serve as the genetic material.  

The clinching experiment was that of Alfred Hershey and Martha Chase in 1952.   Hershey and Chase were working with the bacterial virus Phage T2.  This virus attaches to the bacterial surface and injects its DNA into the cell.  The DNA then replicates, and also provides the information for synthesis of the phage proteins.  

Hershey and Chase grew up phage-infected bacterial cells in a medium containing two radioactive isotopes:  the proteins were labelled with S35, and the DNA was labelled with P32.  Click on each of the flasks to find out why these labels were used.  

The labeled phage were then used to infect new host cells.  Periodically during the infection process, Hershey and Chase interrupted the infection by throwing the phage-bacterial mix into a blender.  Phage that had not yet infected the cells were knocked off.  

Hershey and Chase checked two things during the progress of the experiment:  they looked for bacterial cells that had been successfully infected by the phage and they checked to see which radioactive substance had been taken into the infected cells.  

If the genetic information of the phage was carried in the phage protein, what results would you predict?  
 If the genetic information was carried in the phage DNA, what results would you predict?  

On this bench you will find several test tubes in which the infection was interrupted at various times.  Click on each tube to see the data collected at each time.  Which of your predictions was successful?  What conclusions would you draw from this experiment?