Question

a) Explain the role(s) of the FMN cofactor in Complex I?

b) Explain the role(s) of the FAD cofactor in Complex II?

c) Explain how electron transfer through complex III results in proton pumping across the inner mitochondrial membrane?

d) In complex III, why is it important that the Eo value of cyt bH is more positive than the Eo value of cyt bL?

e) Explain the role(s) of the CuA center in complex IV?

Answer 1

a. Flavinmononucleotide converts NADH to NAD⁺ by reducing itself to FMNH₂ from FMN. Then FMNH₂ transfer two steps of one electron through ubiquinone.

b. Group 2 is also called succinate CoQ reductase which transfer electron from succinate to Q pool through redox reaction in FAD.

c. Two Electron transferred from QH₂ to form quinol at Q_0. And two from quinol to Quinone at Q_i site and theses are left into intermembrane space.

d. It promotes the electron transfer through the chain.

e. CuA form binuclear center for reduction of molemolar oxygen to H₂O by accepting four electron.