A facultative anaerobic bacterium can survive both aerobic and anaerobic conditions. Under both conditions, the cell maintains a proton-motive force across the plasma membrane that drives many cellular processes including nutrient import. Under aerobic conditions, the proton-motive force is produced by a respiratory chain. What is the mode of action of the plasma membrane ATP synthase in this bacterium under aerobic conditions: ATP-hydrolysis mode (H) or ATP-synthesis mode (S)? Write down H or S as your answer.

Question

Quizplus · Accepted Answer

Under aerobic conditions, the proton gradient established by the respiratory chain can drive ATP synthesis, whereas under anaerobic conditions, the ATP synthase pumps protons out (by ATP hydrolysis) to maintain the gradient.

A Facultative Anaerobic Bacterium Can Survive Both Aerobic and Anaerobic