Please answer question 11 II. According to the chemiosmotic theory, an electroch

Question

Please answer question 11

II. According to the chemiosmotic theory, an electrochemical proton gradient is used to synthesize ATP in mitochondria. The oxidation ofcarbohydrates and fats is used to pump protons outside the mitochondrial membrane until the steady state membrane potential is -140 mV and the pH gradient is pH-1.5. Inside the mitochondrion, pHe7.0, [ATP] = 1 mM[P] _ 2.5 mM, [ADP)-1 mM, and T-298 K. ADP + Pi =-ATP + H2O AG. = 31.0 kJ/mol How much chemical potential is required to synthesize ATP inside the mitochondria? a) b) How much free energy is made available by moving 1 mole of H from the outside to the inside mitochondrion. Is the energy released during this transfer enough to drive ATP synthesis? c) How many protons must be translocated per ATP synthesized?

Explanation / Answer

Solution :- give that ,

membranepotential = -140 mv

a) G for the ATP hydrolysis is -30.5 kJ/mol. So, G for its synthesis would be +30.5 kJ/mol

Hence, G' for different concentrations of reactants and products would be

G' = G + RT ln ([ATP]/[ADP] [Pi])

= 30.5 + (8.314) (298) ln ([1x10-3]/[1x10-3] [2.5x10-3])

= 30.5 + (2.48) ln (4x102)

= 30.5 + 14.9

= 45.4 kJ/mol

Thus, 45.4 kJ are required to synthesize ATP.

b) = RT ln [H+]in/[H+]out + ZF

= (8.314) (298) ln [1x10-7]/[3.16x10-6] + (1) (96500) (-0.14)

= (2.48) ln (0.00316)-13.5

= -8.56-13.5

= -22.1 kJ/mol

Since G' = n, -22.1 kJ/mol is required for the movement of 1 mol of proton. This is not enough to drive ATP synthesis as ATP synthesis requires 45.4 kJ/mol.

c) 3 protons must be translocated per ATP synthesized.

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