Question

Complete combustion of ethanol has a AG of 1,300 kJ/mole. What percentage of this energy is captured in the ATP produced? Assume that ATP synthesis requires 50 kJ/mole. 3. Based on the following reduction potentials which includes the reduction potential for enzyme-bound FAD, calculate the AG for complex Il using FADH2 as the electron source. Using your knowledge of proton pumping by mitochondrial electron transport complexes, explain why there are no protons pumped by complex II. COQ + 2 e + 2HCOQH2 E = 0.045 V FAD + 2 e + 2H+ - FADH2 E = 0.031 V - 4. The following figure shows the intermediate of the transketolase mechanism. Use arrow pushing to form the resonance stabilized enzyme intermediate Show the mechanism for If thin intermediate with the given aldose, using the protonated acid/base residue supplied

Answer 1

Step-by-step explanation:

I'd be happy to help! Let's tackle each question one at a time.

1. To calculate the percentage of energy captured in ATP production, we need to first calculate the total energy released from the combustion of ethanol, and then subtract the energy required for ATP synthesis. The energy released from the combustion of ethanol is given by the change in Gibbs free energy (∆G) of the reaction. For the complete combustion of ethanol, the balanced chemical equation is:

C2H5OH + 3O2 -> 2CO2 + 3H2O

The standard ∆G for this reaction is -1,300 kJ/mol. To calculate the energy captured in ATP production, we need to know the efficiency of ATP synthesis. ATP synthesis requires energy, so the actual energy captured will be less than the total energy released. The efficiency of ATP synthesis is the ratio of the energy captured in ATP production to the total energy released. The energy required for ATP synthesis is 50 kJ/mol. Therefore, the energy captured in ATP production is:

Energy captured = -∆G - Energy required for ATP synthesis

Energy captured = -1,300 - 50 = -1,350 kJ/mol

The efficiency of ATP synthesis is:

Efficiency = Energy captured / Total energy released x 100%

Efficiency = (-1,350 / -1,300) x 100% = 103.8%

Therefore, the energy captured in ATP production is 103.8% of the total energy released from the combustion of ethanol. However, this is not physically possible, as the maximum efficiency of ATP synthesis is 100%. Therefore, we can conclude that there is an error in the given values.

2. To calculate the ∆G for complex II using FADH2 as the electron source, we need to use the half-reactions for the reduction of COQ and FAD:

COQ + 2 e- + 2 H+ -> COQH2 E° = 0.045 V

FAD + 2 e- + 2 H+ -> FADH2 E° = 0.031 V

The overall reaction for complex II is:

FADH2 + COQ -> FAD + COQH2

The ∆G for this reaction is:

∆G = -nF∆E°

∆G = -2 x 96.485 x (0.045 - 0.031)

∆G = -2.146 kJ/mol

Therefore, the ∆G for complex II using FADH2 as the electron source is -2.146 kJ/mol.

Complex II does not pump protons because it does not transport electrons to a mobile carrier in the same way that complexes I and III do. Instead, it transfers electrons directly to COQ, which is part of the electron transport chain but does not participate in proton pumping. Therefore, the electrons transferred by complex II do not contribute to the proton gradient across the inner mitochondrial membrane.

3. I'm sorry, but I do not see the figure or any information about the intermediate of the transketolase. Can you please provide more information or context so that I can better assist you with this question?