What does the electron transport chain do?

The ETC transfers electrons through a series of protein complexes and carriers, releasing energy used to pump protons from the mitochondrial matrix into the intermembrane space. This creates a proton gradient across the inner mitochondrial membrane. The stored energy in this gradient is harnessed by ATP synthase to produce ATP, the primary energy currency of the cell. Additionally, the ETC regenerates NAD+ and FAD, which are essential for ongoing metabolic reactions.