In Griffith's experiments, when heat-killed S strain pneumococci were injected into a mouse along with live R strain pneumococci,
A) DNA from the live R cells was taken up by the heat-killed S cells, converting the latter to R cells and killing the mouse.
B) DNA from the heat-killed S cells was taken up by the live R cells, converting the latter to S cells and killing the mouse.
C) proteins released from the heat-killed S cells killed the mouse.
D) RNA from the heat-killed S cells was translated into proteins that killed the mouse.
E) there was no result.

Question

Quizplus · Accepted Answer

Griffith's experiment demonstrated that DNA from the heat-killed S strain bacteria was taken up by the live R strain bacteria, transforming them into the deadly S strain. This transformation caused the mouse to die. The process is known as transformation and is a key mechanism of horizontal gene transfer in bacteria. The uptake of RNA or proteins does not result in transformation and would not have caused the observed effect. Option A is incorrect because it has the direction of the transfer backwards. Option C and D are incorrect because they propose mechanisms that do not correspond with the observed results. Option E is incorrect because there was a clear result observed in the experiment.

In Griffith's Experiments, When Heat-Killed S Strain Pneumococci Were Injected