 Complex II is a parallel electron transport pathway to complex 1, but unlike complex 1, no protons are transported to the intermembrane space in this pathway.Therefore, the pathway through complex II contributes less energy to the overall electron transport chain process.In "Complex III" (cytochrome "bc1" complex or CoQH2-cytochrome "c" reductase; ), the Q-cycle contributes to the proton gradient by an asymmetric absorption/release of protons.