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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.

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.


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