Final answer:
The Hershey-Chase experiment conducted by Alfred Hershey and Martha Chase in 1952 provided evidence that DNA, not protein, is the genetic material responsible for heredity. They used radioactive isotopes to label DNA and proteins of T2 bacteriophage and found that after infection of E. coli cells, only the 32P-labeled DNA entered the cells. This proved that DNA is the carrier of genetic information, setting the stage for the molecular biology revolution.
Step-by-step explanation:
The Hershey-Chase experiment was a critical study in molecular biology that helped answer the question of whether DNA or protein is the genetic material that is responsible for heredity. Conducted by Alfred Hershey and Martha Chase in 1952, this experiment involved the use of the T2 bacteriophage, which is a type of virus that infects bacteria, specifically E. coli cells. Hershey and Chase used radioactive isotopes to label the DNA and proteins of these viruses separately. When they grew E. coli cells infected with T2 bacteriophage in the presence of radioactive phosphorus (32P), only the DNA contained the radioactivity because DNA has phosphorus in its structure. Conversely, when the bacteriophages were grown in the presence of radioactive sulfur (35S), only the proteins showed radioactivity because sulfurs are found in proteins.
Then, they separately infected fresh E. coli cells with either radioactively labeled DNA or proteins. Their observation was that after infection and centrifugation, only the phages with 32P-labeled DNA resulted in radioactive bacterial cells. This indicated that it was the DNA, not the protein, that entered the E. coli cells and was responsible for the production of new phage particles, proving that DNA is the carrier of genetic information.
The Hershey-Chase experiment provided clear evidence that DNA is the genetic material, as proteins labeled with 35S did not enter the bacterial cells, and thus were not involved in the creation of new bacteriophages. This contrasted with the labeled DNA, which was found inside the cells and had been used by the viruses to produce more of themselves.
The experiment by Hershey and Chase built upon previous work, such as Griffith's experiment, which had shown that some factor could transform the properties of bacteria but hadn't identified it as DNA. The discovery by Hershey and Chase set the stage for the molecular biology revolution that followed and was fundamental in confirming DNA's role in heredity.