Final answer:
Bacteriorhodopsin is a membrane transport protein that uses sunlight to pump H+ out of the cell and generate a H+ gradient across the plasma membrane. This process is called chemiosmosis.
Step-by-step explanation:
Bacteriorhodopsin is a membrane transport protein that pumps H+ out of the cell and generates a H+ gradient across the plasma membrane using sunlight. Protons then flow back into the cell, down their electrochemical gradient, in a process associated with ATP formation. This process is called chemiosmosis.