So we can summarize these four steps in the following four. So one, two, three and four. In one, those high energy electrons are extracted from these high energy electron carrier molecules synthesized in the citric acid cycle and glycolysis. And once these electrons are extracted, they move along the proteins, the enzymes of the electron transport chain. And that ultimately allows some of these proteins to actually pump the H plus ions to the intermembrane space, the space between the inner and the outer membrane of the mitochondria. And this establishes an electrochemical gradient for the hydrogen ions.