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.