ElectroPhysiology: Mitochondrial electron transport chain.

The question is regarding the electron transport chain within the mitochondria, specifically how the electrons transport protons through the first and third complex.

The basis of this question can be found at the tutorial at ...

http://www.johnkyrk....tochondrion.swf

As each pair of electrons passes through each individual complex, they cause the transport of two protons across that complex from the matrix to the outer chamber.

The electrons move by passing from the NADH/FADH2, to the flavin inside the complex (FMN) and then "bouncing" between the iron cores of Heme

molecules (porphyrin rings) also within the complex. In the process of jumping between the iron cores they manage to "drag" (?) protons with them.

Question: How, exactly (if we know) is this "dragging" accomplished?

- I.e. Are the high energy electrons in orbitals around these protons (perhaps in a higher energy state and thus a higher shell than the S1) and, thus, form partial bonds (semi-covalent / semi-ionic???) between the iron AND the proton? If this were the case, would these protons have to come from the Nitrogen bound hydrogens off the NADH/FADH2 themselves? One proton appears to come from the NADH/FADH2, but not the second.

- Or, are the electrons being passed resonance style between the iron cores (like electrons passing through a silicon/germanium microprocessor chip) and the protons just follow the magnetic pull through the membranes?

- If so, since the complex membranes are normally proton impermeable, are there passive/active proton channels? Do the electrons perhaps directly activate these channels?

Thanks!