So our NADH molecules produced in the mitochondrial matrix via the citric acid cycle or our pyruvate decreboxylation basically produces a net result of three ATP molecules. But the NADH produced in glycolysis produces a net result of only two ATP molecules. So let's basically summarize our results of what the electron transport chain is and how it actually works. So we have a series of four protein complexes one, two, three and four. And we also have our ATP synthase. Now, by the way, we still haven't discussed what protein complex two actually does.