Redox Reactions: each electron transfer is a redox reaction. One carrier is oxidized, and the other is
reduced. Succinate + FAD + 2e + 2H -> fumarate + FADH2 + 2e + 2H. The next reaction is FADH2 + 2 Fe
(+3) (NHI) -> FAD + 2Fe+2 (NHI) + 2H.
NADH - > NAD+, with the electrons going to the first carrier. This continues on until oxygen becomes
The electron donor, is the reducing agent, that causes a reduction. Standard redox potential E ’, a
voltage value ranks reducing power of electron donor/acceptor pairs. The more negative the E ’, the 0
more the reducing power. Direction of electron transfer is from the more negative to the more positive.
The first reaction of the electron transfer chain is the transfer of NADH electron to coenzyme Q, which is
then to complex III, to cytochrome C, finally to complex IV. In the first reaction, electrons flow from
carriers with more negative E ’0to more positive ones. This results in a negative dG value. The large
changes in standard potential of redox couples occur at the proton pumps.
The cristae has many proteins that act as proton pumps, which pump the protons into the
intermembrane space between the inter membrane and the outer membrane