Question

14. How many ATP's would be formed from 5.5 NADH and 3.5 FADH2 during electron transport and oxidative phosphorylation? Show your work. (8 points)

Answer 1

So, if i explained shortly, during respiration the photosynthetic products are broken down for energy. If you go through glycolysis and citric acid cycle or TCA cycle you already find that there ATP , NADH and FADH2 are made by braking hexose. Here ATP is directly made through substrate level phosphorylation method, and others are energy reserves like FADH2 and NADH.

Those NADH and FADH2 are further go through mitochondrial ETS ( electron transport system ) and used their energy to pump H+ ion in the mitochondrial inter membrane space while going through Complex 1, complex 2, complete 3 and complex 4 simaltinuously and finally gave electron to oxygen and produce water.

So , through pumping H+ out and creating a voltage gradient they make the perfect environment for oxydative phosphorylation event by H+ ATPase or F° - F1 molecules which directed towards matrix in mitochondria. To fix the voltage gradient , H+ ions pass thought the ATPase and come to the mitochondrial matrix again and the energy is use to produce ATP, the energy currency of the cell. This is the story.

Now, who reserves how much energy among NADH and FADH2 is found out by their amount of H+ export from matrix to inter membrane space during transport through ETS and this directly indicate their ATP production efficiency.

It is found that ATP synthase probably require three H+ ion to synthesise one ATP molecule. And , through ETS , when NADH transports its 2 electron to oxygen , 10 H+ ions are exported while for FADH2 the number is only six. So, each NADH and FADH2 produces 2.5 and 1.5 ATP respectively through oxidation.

Then, 5.5 molecules of NADH can produce 13.75 molecules of ATP and 3.5 molecules of FADH2 can produce 5.25 molecules of ATP respectively.