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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