And the third, the other copper atom we call copper B, actually associates with the heme A three to form the heme A three copper B center. And this is where we're going to basically reduce that oxygen to form water molecules, as we'll see in just a moment. So let's actually go through the steps of how this process takes place and how these electrons are transferred from the reduced cytochrome C molecules that we produced along complex three onto the oxygen to form the water molecules. So let's begin with diagram number one. So this is our inner mitochondrial membrane. This is the matrix, and this is the intermembrane space.