The electron transport chain is a rigid causal ladder: electron flow → proton pumping → ΔΨm → ATP. Push fuel past demand and the chain jams — electrons spill onto O₂ as ROS. Hover a complex.
RestingHard workOverloadO₂ cut
0.55
Electrons entering at Complex I / II from the TCA cycle.
0.55
Something to make ATP for. Low demand = nowhere for the gradient to go.
1.00
The only exit for electrons. Close it and the chain backs up instantly.
0.05
A controlled bypass. A small ΔΨm drop cuts ROS steeply for almost no ATP cost.