Question

Elaborate the Hershey-Chase experiment and how it showed DNA was the molecule of heredity

Answer 1

In 1952, Alfred Hershey and Martha Chase conducted a series of experiments to prove that DNA was the genetic material.

T2 bacteriophage were grown in two isotopic mediums in order to radioactively label a specific viral component.Viruses grown in radio active sulfur(35S) had radio labelled proteins (sulfur is present in proteins but not DNA). Viruses grown in radioactive phosphorus (32P) had radiolabeled DNA (phosphorus is present in DNA but not proteins). The viruses were then allowed to infect a bacterium (E. coli) and then the virus and bacteria were separated.The larger bacteria is present in solid pellet while the smaller viruses remained in the supernatant.The bacterial pellet was found to be radioactive when infected by the 32P–viruses (DNA) but not the 35S–viruses (protein)This demonstrated that DNA is the genetic material.