Alfred Day Hershey


His best known
experiment is
Hershey Chase
experiment
Concerned the
replication of genetic
structure of viruses
4 Dec. 1908--- 22 May 1997
1934 -1950
Teaching and research at the Department of Bacteriology
1936
Held an instructorship in bacteriology and immunology
1936 - 1939
Work together with Professor J. J. Bronfenbrenner.
1938
Became assistant professor
1942
Became associate professor
What is T2 ?
•The T2 phage is a
strongly toxic
bacteriophage and
tadpole-shaped virus
• small virus that
infect only bacteria
•Contain 50% DNA and
50% protein
Infect E-coli
•Contains linear double-stranded DNA
tail fibers of
the phage
attach to the
bacterial cell
to initiate
infection
Protein coat of the T2 carries the organ of
attachment to bacteria.
The infective cycle of T2 in E.coil
•Virus attach to the surface of their host cell (a)
•Inject the DNA into the cell (b)
•DNA accumulate,other genes are transcribed and translated (C)
•DNA and protein are assembled into complete virus (d)
•The cell breaks and releases its content of virus (e)
Hershey Chase
Experiment

Radioactive
Sulphur (35S)
non-radioative
DNA?
Radioactive
Phosphorous(35
P)
radioactive
DNA?
