During which stage in the complete oxidation of glucose arc the...

The electron transport chain is primarily used to send protons across the membrane into the intermembrane space. This create a proton-motive force, which will drive ATP synthase in the final step of cellular respiration to create ATP from ADP and a phosphate group. Related Theory In chemiosmosis, the free energy from the series of redox reactions just described is used to pump hydrogen ions across the membrane. The uneven distribution of $\mathrm{H}^{+}$ions across the membrane establishes both concentration and electrical gradients, owing to the hydrogen ions' positive charge and their aggregation on one side of the membrane. If the membrane were open to diffusion by the hydrogen ions, the ions would tend to diffuse back across into the matrix, driven by their electrochemical gradient. Similarly, hydrogen ions in the matrix space can only pass through the inner mitochondrial membrane through an integral membrane protein called ATP synthase. This complex protein acts as a tiny generator, turned by the force of the hydrogen ions diffusing through it, down their electrochemical gradient. The turning of parts of this molecular machine facilitates the addition of a phosphate to ADP, forming ATP, using the potential energy of the hydrogen ion gradient.