why does NADH produces more energy than FADH2 ?

I thought it was visa versa because FADH2 increases the H+ gradient witch produces more ATP.

I' v already lost the mark but it's good to know.thanks already!

1 Answer

  • Anonymous
    10 years ago
    Favorite Answer

    The proton gradient across the inner mitochondrial membrane maintained by action of electron transport chain

    Chain consists of 6 proteins associated with inner mitochondrial membrane:

    NADH dehydrogenase (complex I)

    Succinate coenzyme Q reductase (complex II)

    Coenzyme Q (CoQ) (also called ubiquinone)

    Cytochrome bc1 complex (complex III)

    Cytochrome c (Cyt c)

    Cytochrome oxidase (complex IV)

    NADh feeds into Complex I at the start of the chain whereas the lower energy FADH2 feeds into the chain at a lower energy level at Complex II.

    NADH and FADH2 are powerful reducing agents (negative redox potentials) and readilly donate electrons to molecules having a more positive redox potential . Oxygen as a positive redox potential and readilly accepts electrons.

    The redox difference between NADH and oxygen is +1.14 volts.

    From this it can be calculated that oxidation of NADH by oxygen releases 52.6kcal/mol.

    Phosphorylation of ADP to ATP requires 7.3kcal/mol. (see Hames, Hooper & Houghton page 267-298).

    Oxidation of 1 NADH releases enough energy to make several ATP.

    The 52.6kcal/mol is not released in one reaction but is released in small packets as each member of the electron transport chain reduces the next member. The bulk of the energy is released by 3 reactions involving coplexes I, III and IV. The energy is enough to transport 1 proton across the inner membrane at that point.

    By feeding in at Complex II FADH2 misses out Complex I.

    • Login to reply the answers
Still have questions? Get your answers by asking now.