Now, the electron transport chain uses energy from electrons to generate H+ ion gradient by pumping H+ ions into the intermembrane space. Now, here as we're pumping these H+ ions into the intermembrane space, we're increasing the concentration of H+ ions, which would cause a decrease in our pH.
Now, here, if we take a look and break this up into 7 steps. So in step 1, we're saying that NADH transfers electrons to complex 1. So NADH here is handing over electrons to complex 1, becoming oxidized, and regenerating NAD+. In step 2, FADH2 transfers electrons to complex 2 and it becomes FAD. It's being oxidized as well. Complex 1 and complex 2 will transfer electrons to Coenzyme Q. So they're being transferred here to coenzyme Q. Coenzyme Q then takes those electrons and transfers them to complex 3. Now, complex 3 transfers them to CYTC, which is just cytochrome c. This is just a multi-functional protein that acts as an electron carrier as well within this whole process. Then we're gonna say cytochrome c transfers electrons to complex 4, and then we're gonna say here that, finally, our electrons will be accepted by oxygen or O2. And we're gonna say here, oxygen acts as the final electron acceptor. And we're gonna have it eventually being reduced into water.
Now, notice we have H+ being pumped by complex 1, being pumped by complex 3, being pumped by complex 4. It doesn't happen with complex 2 here. Its complex doesn't move into the intermembrane space like the other complexes. So, note only complexes 1, 3, and 4 pump H+ into the intermembrane space. So, basically, this is the chain of the movement of H+ ions as well as electrons from complex 1 all the way to complex 4 to eventually having O2 being the final electron acceptor.