From the Research
The electron transport chain process utilizes oxygen as the final electron acceptor in cellular respiration, where oxygen accepts electrons at Complex IV to form water, driving ATP production through oxidative phosphorylation. This process is crucial for cellular functions, as it consumes about 90% of the oxygen we breathe, with each oxygen molecule accepting four electrons to become two water molecules 1. The electron transport chain uses a series of electron transfer reactions to generate cellular ATP, and a consequence of electron transfer is the generation of reactive oxygen species (ROS), which contributes to both homeostatic signaling as well as oxidative stress during pathology 2. The key steps in the electron transport chain process involving oxygen are:
- Oxygen enters the process at Complex IV (cytochrome c oxidase), where it accepts electrons that have been passed along the chain from NADH and FADH2.
- When oxygen accepts these electrons, it combines with hydrogen ions (protons) to form water (H2O).
- This reaction is critical because oxygen's high electronegativity creates the strong electrical gradient that drives ATP production.
- Without oxygen accepting electrons, the entire chain would back up and stop functioning, halting ATP synthesis. The most recent study on the mitochondrial respiratory chain provides a brief review of the process, with emphasis on complexes I, III, and IV, which contribute to the generation of protonmotive force across the inner mitochondrial membrane, and drive the synthesis of ATP by the process called oxidative phosphorylation 1.