Answer:
Certain complexes of the mitochondrial electron transport chain pump protons. Protons are pumped across the inner mitochondrial membrane.
Explanation:
The mitochondrial electron transport chain, composed of several electron transporters, is implanted in the inner mitochondrial membrane.
This chain is of great importance in the process of oxidative phosphorylation.
The electron transport chain shuttles electrons from NADH and FADH2 to molecular oxygen, while pumping protons from the mitochondrial matrix to the intermembrane space in order to reduce oxygen and form water. The current of protons powers the catalytic action of ATP synthase.
