Nucleic Acids and the Genetic Material Problem Set 1

Problem 7: Transformation

Frederick Griffith accidentally discovered transformation when attempting to develop a vaccine for pneumonia. He injected mice with samples from S-strain (virulent) and/or R-strain (nonvirulent) pneumococci bacteria (Streptococcus pneumoniae) . Which of the following results is NOT consistent with Griffith's experiments?
A injected S-strain; mouse dies.

B injected R-strain; mouse lives.

C injected heat-killed S-strain; mouse lives.

D injected mixture of heat-killed S-strain and live R-strain; mouse lives.

The key to the eventual successful demonstration that DNA is the genetic material came when Griffith demonstrated that the injection of heat killed smooth strain extract with live rough strain bacteria led to the death of mice. Avery and co-workers followed up of these experiments showing that the active agent in extracts was DNA.

E injected mixture of heat-killed R-strain and live S-strain; mouse dies.

The Biology Project
University of Arizona
Thursday, October 3, 1996
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