Cellular Respiration and Oxygen Amounts

[shefv]

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So I know the equation: C6H12O6 + 6O2 -> 6CO2 + 6H2O
This means that 6 oxygen molecules are required for the metabolism of each glucose molecule.

Given that O2 is needed directly in ETC, I am wondering where exactly the 6O2 is being used?

I was thinking that 1/2O2 + H2 -> H2O during ETC and we know that H is coming from NADH and FADH2, so I was trying to add up the numbers like that but it's not quite making sense.

For each glucose molecule, we get

2 NADH from PDC = 2 H for ETC
6 NADH + 2 FADH2 = 8H for ETC

The number are not quite adding up. Can someone show me where exactly the 6O2 are being used up?

Thanks

 

[MrRed]

You have one O2 molecule used for every 4 electrons transported through the entire ETC.
1 glucose will net you
2NADH (glycolysis) + 2 NADH (PDC) + 6NADH + 2 FADH2(krebs cycle)

Each of these molecules transfers 2 electrons to the ETC.
So 2 + 2 + 6 + 2 = 12molecules x 2electrons per molecule = 24electrons/4electrons per O2 = 6O2


EDIT: I should have added, if you don't see where I'm getting the 4 electrons per 1O2 molecule its time for you to review the mechanism of the cytochrome c oxidase complex in the ETC (complex IV).