You are a volunteer for Nurses Without Borders and are being sent on a humanitarian mission. You are somewhat concerned because you have learned from the CDC website that antibiotic-resistant Haemophilus influenzae is common in the country to which you are being sent. This encapsulated, Gram-negative bacterium can cause a variety of illnesses, including community-acquired pneumonia. You do some research on the genetics of this pathogen.
-H. influenzae has genes that it needs to make pili for attachment to host cells. These pili genes are not always expressed; sometimes the bacterium turns them off and does not produce pili. This is an example of
A) phase variation.
B) antigenic sensing.
C) two-component control.
D) transduction.
E) gene splicing.

Question

You are a volunteer for Nurses Without Borders and are being sent on a humanitarian mission. You are somewhat concerned because you have learned from the CDC website that antibiotic-resistant Haemophilus influenzae is common in the country to which you are being sent. This encapsulated, Gram-negative bacterium can cause a variety of illnesses, including community-acquired pneumonia. You do some research on the genetics of this pathogen. 
-H. influenzae has genes that it needs to make pili for attachment to host cells. These pili genes are not always expressed; sometimes the bacterium turns them off and does not produce pili. This is an example of 
A) phase variation.
B) antigenic sensing.
C) two-component control.
D) transduction.
E) gene splicing.

Quizplus · Accepted Answer

The turning on and off of the pili genes is an example of phase variation, which is a mechanism used by bacteria to switch between different phenotypic variations in response to changing environmental conditions.

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