Electron Transport Chain

Correct Answer: A. NADH and FADH2 are oxidized, hydrogen ions move into the intermembrane space, ATP is generated.

In animal cells the electron transport chain (commonly referred to as the ETC) is instrumental in cellular respiration. During the ETC, the two energy carriers, NADH and FADH2, are oxidized. Their electrons are transferred to the cytochromes embedded in the intermembrane of the mitochondria. As the electrons “jump” along the ETC, hydrogen ions are pumped out of the matrix into the intermembrane space. As a result of the hydrogen ion gradient (an electrochemical gradient), the hydrogen ions move through the ATP synthase out of the intermembrane space back into the matrix, thereby making ATP for the cell. The only answer option that details this process accurately is [A]. Note: NADPH, is an energy carrier in photosynthesis. You can think that the “P” is for plants to help remember, but it is really for phosphorus.

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