What is the significance of oxygen in net?

Oxidative phosphorylation is the terminal process of cellular respiration in eukaryotes. During oxidative phosphorylation electrons are transferred from NADH or FADH2 — created in glycolysis, fatty acid metabolism and the Krebs cycle — to molecular oxygen, via a series of protein complexes located in the inner mitochondrial membrane. Protons are pumped from the mitochondrial matrix into the intermembrane space as a result of this flow of electrons. This generates a pH gradient and a transmembrane electrical potential across the membrane. This is a form of potential energy which is referred to as a proton-motive force. The protons flow back into the mitochondrial matrix via a large protein complex, ATP synthase. This is how most of the ATP is created in a eukaryotic cell. This is the reaction that ATP synthase catalyses: