[Campbell Biology P.13] If a chemical inhibitor specifically prevented the generation of an... | Practice Question

If a chemical inhibitor specifically prevented the generation of an H+ gradient across the bacterial cell membrane, which of the following immediate effects would be observed regarding bacterial locomotion as described in the figure?

  • A: The flagellar motor would rotate faster due to reduced resistance.
  • B: Protons would be actively transported into the cell, reversing flagellar rotation.
  • C: The bacterial flagellum would cease to propel the cell due to a lack of power for the flagellar motor.
  • D: The cell would switch to an alternative energy source for flagellar movement, such as ATP.

Explanation

The 'Locomotion' section states: 'A gradient of H+ powers the bacterial flagellum. An electron transport chain generates this gradient, establishing a higher concentration of H+ outside the bacterial cell. Protons reentering the cell provide a force that causes the flagellar motor to rotate.' Without the H+ gradient, the power source for the motor is absent, and thus locomotion ceases.