Hershey and Chase Experiment

Hershey and Chase Experiment:

Another supporting evidence that DNA as the genetic material came from the results of experiments designed by Alfred Hershey and Martha Chase in 1952.

They used T-even Bacteriophages T2. When the Bacterioph-ages infect a bacterial cell, the following events occur.

·     Attachment of phage tail fibers to bacterial wall

·     Same components of the phage enters the bacterial ell

·     The virus uses the cellular machinery of the host for viral reproduc-tion.

·     Viral components accumulate, assembly of mature phages takes place

·     Bacterial cell lysed and many new phages released.

Hershey and Chase knew from several experiments, the inde-pendent functions of phage protein and nucleic acid in the reproduction process associated with the bacterial cell.

The T2 phage consists of approximately 50% protein and 50% DNA. Hershey and Chase used the radioisotopes ³²P and ³⁵P plus DNA contains P but not sulfur. Proteins contain sulfur but not phos-phorous. So DNA will be labeled with ³²P and the protein with ³⁵P and when infected with T₂ virus.the resulting progeny phages will have either a radioactive labeled DNA core or a radioactively labeled protein coat. The results are summarized below.