Final answer:
The electron transport chain in cellular respiration involves the transfer of electrons from NADH and FADH2 to oxygen, creating water and an electrochemical gradient that drives ATP synthesis through ATP synthase.
Step-by-step explanation:
The flow of electrons in the electron transport chain involves a series of reactions where electrons are passed from NADH and FADH₂ to molecular oxygen (O₂), ultimately forming water (H₂O). This process occurs in the inner mitochondrial membrane in eukaryotic cells and is crucial for the production of ATP, the energy currency of the cell. As electrons are shuttled between various membrane-embedded protein complexes (I through IV) and mobile carriers like ubiquinone and cytochrome c, energy is released and utilized to pump protons (H+) from the mitochondrial matrix to the intermembrane space, creating an electrochemical gradient.
Subsequently, these protons flow back into the mitochondrial matrix through ATP synthase, which harnesses this energy to synthesize ATP in a process known as oxidative phosphorylation. This stepwise transfer of electrons through the chain prevents the liberation of energy in an explosive manner, allowing the cell to capture and store it efficiently in the form of ATP.
The electron transport chain is thus a key component in cellular respiration, where the sequential reduction and oxidation (redox) reactions facilitate controlled energy release for ATP synthesis, with the final electron acceptor being oxygen, reduced to water.