Ok so I understand redox reactions in the context of chemistry, but in bio they seem to be doing something different.
First question:
the following reaction:
C[sub]6[/sub]H[sub]12[/sub]O[sub]6[/sub] + 6O[sub]2[/sub] -> 6CO[sub]2[/sub] + 6H[sub]2[/sub]O
THe book says “glucose is oxidized to carbon dioxide, while the oxygen is reduced to water”… I’m not following this at all. From the chemistry I’ve gone through so far, individual atoms or ions are oxidized and reduced and it’s fairly easy (though somewhat tedious) to figure out which was which. So by what definition of oxidation and reduction can you say some reactant was oxidized into a product which is part reactant A and part reactant B?
Second question (along the same lines probably):
Lecturer says:
“Glucose is oxidized to pyruvic acid. We should be able to figure this out easily because if NADH is produced, those hydrogen atoms had to come from somewhere.”
So um… is the definition of redox in this case the transfer of hydrogen atoms? The removal of hydrogen atoms from a reactant constitutes oxidation?
Ok so I can maybe wrestle through those… but this one is really confusing me:
After glycolysis…pyruvate, C[sub]3[/sub]H[sub]3[/sub]O[sub]3[/sub], enter the mitochondrion… CO[sub]2[/sub] is removed so now the molecule is C[sub]2[/sub]H[sub]3[/sub]O…Then it says “The remaining two-carbon fragment is oxidized to form a compound named acetate. An enzyme transfers the extracted electrons to NAD+, storing the energy in the form of NADH.” So what exactly is taken off the C[sub]2[/sub]H[sub]3[/sub]O to form NADH out of NAD+? The standard reduction of NAD+ requires two Hydrogen atoms, so I would assume it would have to take two H’s off the molecule. Perhaps because there are extra electrons left on the molecule, it can reduce NAD+ without 2 H’s…but in order to form NADH there must be at least one H added right? Only problem is after this oxidation, all 3 H’s are supposedly still on the molecule.
What am I missing?
please help…trying to study and hit a road block.