What is the fate of NADH after it donates its electrons to the electron transport system? A) NAD⁺ is excreted from the cell and sent to the liver for final degradation. B) NADH is used for cellular biosynthesis. C) NAD⁺ is re-reduced by the TCA cycle or glycolysis and returns to electron transport system, where the process is repeated. D) NAD⁺ is fed into the TCA cycle for oxidation of CO₂.

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Quizplus · Accepted Answer

After donating its electrons to the electron transport system, NADH is re-reduced by the TCA cycle (also known as the Krebs cycle or citric acid cycle) or glycolysis and returns to the electron transport system to donate more electrons. This process allows for the continuous production of ATP through oxidative phosphorylation. Option A is incorrect because there is no molecule called NAD⁺. Option B is incorrect because NADH is not directly used for biosynthesis. Option D is incorrect because NADH is not fed into the TCA cycle for oxidation of CO₂, rather it is a byproduct of TCA cycle and glycolysis.

What Is the Fate of NADH After It Donates Its