Hershey-Chase experiment

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The Hershey-Chase experiment was a series of experiments conducted in 1952 by Alfred Hershey and Martha Chase. It identified DNA to be the genetic material of phages and, ultimately, of all organisms. Before this experiment was conducted, it was suspected that proteins were the genetic material in viruses, not DNA. A phage is a small virus that infects bacteria. It consists of a protein coat that encloses the genetic material. When a phage infects a bacterium, it inserts its genetic material into the bacterium, while its coat remains outside.

Structural overview of T2 phage

In a first experiment, T2 phages with radioactive ³²P-labeled DNA infected bacteria. In a second experiment, T2 phages with radioactive ³⁵S-labeled protein infected bacteria. In both experiments, bacteria were separated from the phage coats by blending followed by centrifugation. In the first experiment, most radioactivity was found in the infected bacteria, while in the second experiment most radioactivity was found in the phage coat. These experiments demonstrated that DNA is the genetic material of phage and that protein does not transmit genetic information.

Hershey shared the 1969 Nobel Prize in Physiology or Medicine for his “discoveries concerning the genetic structure of viruses”