Question

1.) Choose the correct path taken by a pair of electrons as they travel down the electron-transport chain.

a) NADH → Complex I → CoQ → Complex III → Cyt c → Complex IV → O2

b) NADH → Complex I → Complex II→ Complex III → Cyt c → Complex IV → O2
  
c) FADH2 → Complex II → CoQ → Complex III → Cyt c → Complex IV → O2
  
d) FADH2 → Complex I → CoQ → Complex III → Cyt c → Complex IV → O2

e) Two of the answers are correct

2.) Carbon monoxide is considered toxic because it acts on Complex IV. How would the addition of carbon monoxide to actively respiring mitochondria affect the relative oxidation-reduction states of all components of the electron-transport chain?

a) All four complexes would remain reduced because they function as a multisystem complex.
  
b) Complexes I, II, and III would be reduced and Complex IV would be oxidized.

c) All four complexes would remain oxidized because they function as a multisystem complex.

d) Complexes I, II, and III would be oxidized but Complex IV would remain reduced.

Answer 1

1) The correct path taken by a pair of electrons as they travel down the electron-transport chain are

correct option a) NADH → Complex I → CoQ → Complex III → Cyt c → Complex IV → O₂

(another correct path is avaliable in the form of pair of electron in the electron chain (c)

FADH2 → Complex II → CoQ → Complex III → Cyt c → Complex IV → O₂)

2) The addition of carbon monoxide to actively respiring mitochondria affect the relative oxidation-reduction states of all components of the electron-transport chain as carbon monoxide Blocks electron transport and proton pumping at complex IV

therefore option d) is correct.i.e.Complexes I, II, and III would be oxidized but Complex IV would remain reduced.