Which one of the following microorganisms was used by Frederick Griffith in his ‘Transforming Principle’ experiment?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Streptococcus
In 1928, Frederick Griffith worked with Streptococcus pneumoniae, the bacterium that causes pneumonia. He used two strains: the S strain (smooth, with a polysaccharide coat, virulent) and the R strain (rough, not virulent). When heat-killed S bacteria were injected into mice with live R bacteria, the mice died, and live S bacteria were found in them. Some ‘transforming principle’ from the dead S bacteria had changed the R strain. This was the transfer of the genetic material.
(1) Trichoderma — Incorrect. Trichoderma is a fungus used as a biocontrol agent.
(2) Staphylococci — Incorrect. Griffith did not use Staphylococcus.
(3) Escherichia — Incorrect. E. coli is used in the Meselson and Stahl experiment and as the host in recombinant DNA technology, not in Griffith’s work.
(4) Streptococcus — Correct. Griffith used Streptococcus pneumoniae.
NCERT Extract:
The Search for Genetic Material – …
