In 1952, Hershey
and chase infected bacteria with T2 phages that
had been radioactively labeled either in their
DNA component (with 32P) or in their protein
component (with 32S).The infected bacteria were
agitated in a blender, and two fractions were
separated by centrifugation. One contained the
empty phage coats that were released from the
surface of the bacteria; these consist of
protein and therefore carried the 32S
radioactive label. The other fraction consisted
of the infected bacteria themselves.
Most of the 32P label was present in the
infected bacteria. The progeny phage particles
produced by the infection contained 30% of the
original 32P label. The progeny received very
little less than 1% of the protein contained in
the original phage population.
therefore showed directly that the DNA of parent
phages enters the bacteria and than becomes part
of the progeny phages, exactly the pattern of
inheritance expected of genetic material.