Within the context of cellular respiration, what does ATP synthase do?

ATP synthase plays a crucial role in cellular respiration by producing ATP, the primary energy currency of the cell, using the energy derived from a proton gradient. This process occurs during oxidative phosphorylation, specifically in the mitochondria.

As electrons are transferred along the electron transport chain, they result in the pumping of protons (H+ ions) from the mitochondrial matrix into the intermembrane space. This creates a proton gradient, where there is a higher concentration of protons outside the matrix than inside. ATP synthase harnesses the energy from this gradient, allowing protons to flow back into the matrix through its rotor.

The flow of protons drives the synthesis of ATP from ADP and inorganic phosphate (Pi) through a process called chemiosmosis. This mechanism is highly efficient, as the energy stored in the proton gradient directly facilitates the phosphorylation of ADP to form ATP. Thus, ATP synthase is essential in converting energy stored in the proton gradient into a readily accessible form of energy, which cells use to perform various functions.