what prevents pyruvate from entering the mitochondria with the lack of oxygen?

[MedGrl@2022]

I just learned that fermentation occurs in the cytoplasm of the cell. I know that fermentation occurs in the lack of oxygen. However, what prevents the pyruvate from entering the mitrochondria and going through the Kreb's Cycle. Isn't oxygen just necessary during the Electron Transport Chain?

Thank you for all your help.

Sincerely,

Verónica

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[Redpancreas]

I just learned that fermentation occurs in the cytoplasm of the cell. I know that fermentation occurs in the lack of oxygen. However, what prevents the pyruvate from entering the mitrochondria and going through the Kreb's Cycle. Isn't oxygen just necessary during the Electron Transport Chain?

Thank you for all your help.

Sincerely,

Verónica

Hey. It's not that there's actually one signaling molecule that goes and intercepts pyruvates path into the mitochondria. Rather it's the idea that if there's no oxygen then there's nothing to accept electrons at the end so then the electrons stop flowing and thus there is less of a need for FADH2 and NAD to do their jobs so intermediates in the TCA cycle back log and the TCA no longer works longer works.


This is more of a big picture question.

Think:

A-> B -> C -> D etc.


If D accumulates then based off of equilibrium it'll start doing reverse reaction. (All these reactions catalyzed by enzymes are reversible but usually favor one direction)

 

[cheesier]

Pryuvate is transported into the mitochondria via a symport with H+ ion. No oxygen = no electron transport = no H+ to cotransport along with the pyruvate, so it can't get into the mitochondria.