Pyruvate...reduced or oxidized?

[csx]

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Is pyruvate reduced or oxidized during aerobic resp? what about fermentation?

 

[Shirafune]

I think during the pyruvate dehydrogenase complex pyruvate is being oxidized because NAD+ is being reduced to NADH along with the release of CO2 and attachment to CoA-SH. Maybe somebody can clarify on this.

During fermentation, the goal is to regenerate NAD+ from NADH. Since you're going from NADH to NAD+ (oxidation), pyruvate should be reduced to lactate or ethanol.

 

[sillyjoe]

I think during the pyruvate dehydrogenase complex pyruvate is being oxidized because NAD+ is being reduced to NADH along with the release of CO2 and attachment to CoA-SH. Maybe somebody can clarify on this.

During fermentation, the goal is to regenerate NAD+ from NADH. Since you're going from NADH to NAD+ (oxidation), pyruvate should be reduced to lactate or ethanol.

Pyruvate is eventually oxidized during aerobic respiration in the mitochondria. This makes sense since you are using the energy from the electrons of pyruvate via the electron transport and electromotive force created by the [H+] gradient to generate ATP.

During anaerobic respiration you MUST regenerate NAD+ used during the oxidation of glyceraldehyde-3-phosphate otherwise glycolysis will cease to function due to the lack of NAD+. Therefore, during glycolysis pyruvate is reduced using NADH as the reducing agent and depending on what organism you are it will be reduced to either lactate or ethanol to regenerate NAD+.

 

[NextStepTutor_1]

Is pyruvate reduced or oxidized during aerobic resp? what about fermentation?

@sillyjoe is correct. During aerobic respiration, pyruvate is eventually oxidized.
To remember this, think about oxidation as the breakdown of some compound or material. Using a complete glucose molecule before glycolysis as an example, you can see that it is chalk full of potential energy by regarding the amount of ATP produced during aerobic respiration (2 ATP via glycolysis, 2 ATP via Krebs Cycle, and 32 via the Electron Transport Chain). In order to get to that energy, we must break down glucose and that's oxidation.

Contrarily, reduction can be thought of building up a compound (simply put and in a basic chemistry sense, adding hydrogens to a compound).



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[pepocho]

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[NextStepTutor_1]

For Kreb Cycle, is it 2 ATP for each pyruvate or for each glucose molecule. Since glucose is converted into 2 pyruvates, I just wanted some clarifications. Thanks

The Krebs Cycle produces 2 ATP molecules per glucose molecule. You are right in that one glucose molecule produces 2 molecules of pyruvate, and each molecule of pyruvate is able to produce 1 ATP after becoming Acetyl CoA and entering the Krebs Cycle. So, to condense, 1 glucose oxidizes into 2 pyruvate that turns into 2 Acetyl CoA that gives 2 ATP.


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