Avery, MacLeod, and McCarty

April 4, 2003
Biology P. 7


Avery, MacLeod, and McCarty


Problem Statement

What molecule allows the transfer of genetic information to transform Streptococcus pneunomoniae from a non virulent (R) strand to a virulent strand (S) of Streptococcus pneunomoniae?


Background

In 1928 an army doctor named Fred Griffith tried to develop a vaccine against Streptococcus pneunomoniae which caused a type of pneumonia. Griffith had no success in creating a vaccine, but he found out that the bacteria had two different forms. One form was the smooth (S) form and the other was the rough form (R). The rough (R) form of the bacteria was not harmful, but the smooth (S) form was lethal. He created an experiment in which he Heat-Killed the lethal smooth form of the bacteria and mixed them with the harmless rough form. When he did this he discovered that the rough form of the bacteria was “transformed” into the lethal smooth (S) form of the bacteria.


Hypothesis

If SIII, trypsi...