And in the next many lectures to come, we're basically going to look at the details of what actually happens within each one of these complexes. So let's begin with protein Complex to one. Now, by the way, this is a diagram of only one of the electron transport chains of the many electron transport chains that exist in a single mitochondrial inner membrane. So this is the inner mitochondrial membrane, this is the mitochondrial matrix and this is the intermembrane space that exists between the two membranes of the mitochondrion. So protein complex one is also known as NADH dehydrogenase or NADH oxidoreductase. And that's because this is the protein complex that actually accepts those high energy electrons from the NADH molecules which were produced in glycolysis as well as the citric acid cycle.