QUESTION 4 [25 total marks] (a) In cells, Adenosine Triphosphate (ATP) is primarily synthesised from Adenosine Diphosphate (ADP) by using the proton-motive force generated across the inner membrane of mitochondria. Briefly explain the general role of electrons (e-) and protons (H+) in generating this proton-motive force. (General principles only; a diagram may be useful. The mechanism by which the proton-motive force drives the ATP synthase is not needed) (4 marks) (b) Shown below are the fully oxidised forms of three major transporters of electrons (e-) and protons (H+) to, or from, Complex 1 of the electron transport chain on the mitochondrial inner membrane. NAD+ is Nicotinamide Adenine Dinucleotide; FAD is Flavin Adenine Dinucleotide; R indicates the non-redox reactive part of the molecule. (i) Draw the fully reduced form for each. (3 marks) (ii) Explain briefly the role each plays in the transport of electrons through Complex 1. (6 marks)