How efficient is ATP synthesis. It was previously indicated that theoretically each pair of electrons transferred from NADH to O2 COULD provide suffiecient free energy to synthesize up to 7 ATP.... but that was also hedged by indicating that it would likley be far fewer.
In the simple case, there are three complexes that are involved in transporting H+ across the inner mitochondria membrane. In actuality each complex pumps enough H+ to synthesize one ATP for every pair of electron transferred.
Recalling the summary from page 4 of this module.....
Now we can convert each of those NADH to ~3 ATP and each reduced flavin to 2 ATP (remember that the the reduced flavin is from succinate dehydrogenase .... which IS complex II .... and that complex II does not pump H+ like complex I, III and IV and the others.
|2 ATP||2 NADH||none|
|Pyruvate Dehydrogenase||none||2 NADH||none|
|2 ATP (as GTP)||6 NADH||2 reduced flavin|
|OVERALL totals||4 ATP||10 NADH||2 reduced flavin|
|CONVERT to ATP |
|4 ATP||30 ATP||4 ATP|
This data ignores some energy lost on tranporting NADH into the mitochondria... but that is fine by me
Where as we obtained 2 ATP per glucose from the non-oxidative metabolism here including oxidative phosphorylation our total yield can be up to 38...... almost 20 times more energy yielded for the same glucose molecule through the anaerobic processes. All due to our use of O2 as a terminal electron acceptor.