# What is oxygen's role in the electron transport chain?

Mar 14, 2018

See Below

#### Explanation:

There are a lot of parts and pieces involved in the electron transport chain, but with respect to Oxygen, the simple answer is Oxygen is the place where the electrons go, it i sthe thing that gets reduced.

I'm not going to link to all the membranes and chemical reactions, but rather just refer to something simple like a carbon in a typical fat.
$- C {H}_{2} -$ this is what a carbon in a fat looks like (in general).
As that carbon sits now, it has a ~ -2 oxidation state.

When you exhale that carbon as $C {O}_{2}$ (after cellular respiration and oxidative phosphorylation, etc), the C has a +4 oxidation state.

That means for the Carbon:
${C}^{-} 2 = {C}^{\text{+4}} + 6 {e}^{-}$
Those 6 electrons have to go somewhere. And they go onto Oxygen!
You breath in elemental ${O}_{2}$ with a zero oxidation number. That carbon above turns into a $C {O}_{2}$ and basically 1 water, ${H}_{2} O$
So that Carbon needs to get rid of 6 electrons...and in $C {O}_{2}$, each Oxygen has a -2 oxidation state (from zero to -2), and the water oxygen has a -2 oxidation state (from zero to -2). So when that Carbon in the fat gets oxidized and you breath it out as $C {O}_{2}$.
The place were those 6 electrons went is onto the ${O}_{2}$ that you breathed in (and breathed out as $C {O}_{2}$ and maybe some water (simplistically speaking)