And what this proton comp, or what this complex does is it accepts those electrons from the Q carrier molecule, the Ubiquinone. And then it takes those electrons and transfers them onto another electron carrier known as cytochrome C. Now, this, just like protein complex one, is also proton pump. And as a result of the movement of those electrons within this complex, that allows this structure to actually pump those protons into the intermembrane space from the matrix of the mitochondria. And finally, if we examine protein complex four, this is essentially where we take those electrons and we use them to reduce oxygen molecules into water molecules. So this is where we find the final electron acceptor of the electron transport chain. And this also uses the movement of those electrons to pump those protons out of the matrix and into the space between the two membranes.