The Hershey & Chase Experiment (Part 2)

    During the process of infection of bacteria by bacteriophages, a quick spin in a blendor shears phage away from the outside of the bacteria. Analysis of the bacterial and supernatant fractions afterward demonstrates that phosphorus-labelled DNA inside the phage shows up in bacteria (left), whereas the sulfur-labelled protein in the external coat remains in the supernatant (right). Further, bacteria with labelled DNA go on to produce progeny phage that are also labelled. This biological experiment confirms Avery's conclusion that DNA is the transforming substance, and shows that transformation is heritable.


All text material ©2011 by Steven M. Carr