<P> Hershey shared the 1969 Nobel Prize in Physiology or Medicine with Max Delbrück and Salvador Luria for their "discoveries concerning the genetic structure of viruses ." </P> <P> In the early twentieth century, biologists thought that proteins carried genetic information . This was based on the belief that proteins were more complex than DNA . Phoebus Levene's influential "tetranucleotide hypothesis", which incorrectly proposed that DNA was a repeating set of identical nucleotides, supported this conclusion . The results of the Avery--MacLeod--McCarty experiment, published in 1944, suggested that DNA was the genetic material, but there was still some hesitation within the general scientific community to accept this, which set the stage for the Hershey--Chase experiment . </P> <P> Hershey and Chase, along with others who had done related experiments, confirmed that DNA was the biomolecule that carried genetic information . Before that, Oswald Avery, Colin MacLeod, and Maclyn McCarty had shown that DNA led to the transformation of one strain of Streptococcus pneumoniae to another . The results of these experiments provided evidence that DNA was the biomolecule that carried genetic information . </P> <P> Hershey and Chase needed to be able to examine different parts of the phages they were studying separately, so they needed to isolate the phage subsections . Viruses were known to be composed of a protein shell and DNA, so they chose to uniquely label each with a different elemental isotope . This allowed each to be observed and analyzed separately . Since phosphorus is contained in DNA but not amino acids, radioactive phosphorus - 32 was used to label the DNA contained in the T2 phage . Radioactive sulfur - 35 was used to label the protein sections of the T2 phage, because sulfur is contained in amino acids but not DNA . </P>

Who demonstrated that dna is the genetic material of t2 phage