When enough protons have accumulated, the proton motive force powers the formation of ATP. So a gradient allows cells to save up protons as “loose change”, and that makes all the difference in the world — the difference between growth and no growth, life and no life.

What is the proton gradient used to do?

The proton gradient produced by proton pumping during the electron transport chain is used to synthesize ATP. Protons flow down their concentration gradient into the matrix through the membrane protein ATP synthase, causing it to spin (like a water wheel) and catalyze conversion of ADP to ATP.

What is the function of the proton gradient in the mitochondria?

The electrochemical proton gradient across the inner mitochondrial membrane is used to drive ATP synthesis in the critical process of oxidative phosphorylation (Figure 14-14). This is made possible by the membrane-bound enzyme ATP synthase, mentioned previously.