Martha Chase & Alfred Day Hershey By:Shakera Williams Martha Chase O Birth- November 30,1927 O In 1950, she received her bachelor degree from The College of Wooster O In 1952, she was known as the American geneticist who was a laboratory assistant to bacteriophage expert Alfred Hershey. They created the Hershey- Chase experiment. O In 1964, she received her PhD from the University of Southern California. O Death- August 8, 2003 Alfred Hershey O Birth- December 4,1908 O 1930- received his B.S. degree from Michigan State in O O O O chemistry 1934- received his PhD in bacteriology In 1950, he joined the Carnegie Institute of Washington Department of Genetics 1952- conducted the Hershey-Chase experiment with Martha Chase Death- May 22, 1997 The Hershey-Chase Experiment O 1952- This experiment provided additional evidence that DNA, not protein, was the genetic material of life O Hershey and Chase showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. O Hershey and Chase conducted their experiments on the T2 phage, a virus whose structure had recently been shown by electron microscopy. The phage consists of a protein shell containing its genetic material. Experiment Continued O In their first set of experiments, Hershey and Chase labeled the DNA of O O O O O phages with radioactive Phosphorus-32 This element phosphorus is present in DNA but not present in any of the 20 amino acids from which proteins are made In their second set of experiments, they labeled the phages with radioactive Sulfur-35 Sulfur is present in the amino acids cysteine and methionine, but not in DNA Then they sheared the viral protein shells off of infected cells using a high-speed blender and separated the cells and viral coats by using a centrifuge. After separation, the radioactive S35 tracer was observed in the protein shells, but not in the infected bacteria, supporting the hypothesis that the genetic material which infects the bacteria was DNA and not protein.