How many ATP molecules can be produced from one molecule of FADH2?

One molecule of FADH2 can produce approximately 1.5 ATP molecules during oxidative phosphorylation within the electron transport chain. This process occurs after the citric acid cycle and involves the transfer of electrons from FADH2 to the electron transport chain, which ultimately contributes to the generation of ATP through chemiosmosis.

FADH2 donates electrons to complex II of the electron transport chain, which is positioned lower in the series compared to NADH, which donates its electrons to complex I. As a result, the energy yield from FADH2 is slightly less than that from NADH. The amount of ATP produced from one FADH2 is based on the proton pumping that occurs as electrons are transferred through the electron transport chain. FADH2 leads to the pumping of fewer protons into the intermembrane space compared to NADH. Since approximately 2.5 ATP are produced per NADH, the yield from FADH2 is typically reported as about 1.5 ATP per molecule, reflecting this difference in proton pumping and ATP generation.