Microbiology researchers conduct a series of experiments to determine how pathogenicity is transmitted among different strains of Streptococcus pneumoniae. In the first experiment, they inject nonvirulent strain A into the peritoneal cavity of laboratory mice and observe no ill effects. In the second experiment, researchers subject virulent strain B to a detergent agent that kills and lyses the bacterial cells. They then inject the lysate into the peritoneal cavity of a new group of mice and again observe no ill effects. During a third experiment, they inject live strain A bacteria in combination with the killed strain B lysate, resulting in death of the mice. Which of the following genetic processes most likely accounts for the observed findings of these experiments?

Question

Microbiology researchers conduct a series of experiments to determine how pathogenicity is transmitted among different strains of Streptococcus pneumoniae.  In the first experiment, they inject nonvirulent strain A into the peritoneal cavity of laboratory mice and observe no ill effects.  In the second experiment, researchers subject virulent strain B to a detergent agent that kills and lyses the bacterial cells.  They then inject the lysate into the peritoneal cavity of a new group of mice and again observe no ill effects.  During a third experiment, they inject live strain A bacteria in combination with the killed strain B lysate, resulting in death of the mice.  Which of the following genetic processes most likely accounts for the observed findings of these experiments?

Quizplus · Accepted Answer

Eductional Objective: Streptococcus pneumoniae is able to undergo transformation, which allows the bacterium to take up exogenous DNA fragments and express the encoded proteins.  Through this method, strains of S pneumoniae that do not form a capsule can acquire the genes that code for the capsule and therefore gain virulence.

Microbiology Researchers Conduct a Series of Experiments to Determine How