Microbiology Researchers Conduct a Series of Experiments to Determine How

question 197

Multiple Choice

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?

• A)Direct uptake of extracellular DNA
• B)Phage-mediated DNA transfer
• C)Pilus-mediated DNA transfer
• D)Spontaneous DNA mutation
• E)Transposon-mediated DNA transfer

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