Final answer:
The redox potential increases and the free energy decreases as electrons move through the electron transport chain, resulting in the synthesis of ATP.
Step-by-step explanation:
Moving through the protein complexes of the electron transport chain from beginning to end, redox potential increases (becomes more positive) and free energy decreases as it is released. In the electron transport chain, electrons move from donors like NADH and FADH2 with lower redox potentials to acceptors like oxygen with higher redox potentials. This sequential transfer of electrons through a series of redox reactions releases energy which is captured and used to pump protons across the mitochondrial membrane, establishing a proton gradient. This gradient then powers the synthesis of ATP.
During biological oxidation, the electron transport chain (ETC) consists of protein complexes and electron carriers embedded in the inner mitochondrial membrane. The process of electron transport and ATP synthesis is called
oxidative phosphorylation . As electrons move through the complexes, they go from a higher energy state to a lower energy state, which is an exergonic process. The sequential release of energy in small, controlled bursts rather than a single, destructive explosion allows the cell to harness this energy effectively to produce ATP.