Cellular Respiration location

[El Curandero]

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Hi all,

I know that glycolysis occurs in the cytosol and TCA occurs in the matrix but when does the cross over occur, which molecule is shuttled through the outer and inner mitochondrial membrane, and how is it carried out?

El Curandero

 

[mcatjelly]

Hey, I recommend you post these questions instead in the MCAT Study Question forum at the top of the page. 🙂

 

[El Curandero]

Hey, I recommend you post these questions instead in the MCAT Study Question forum at the top of the page. 🙂

Ah, I didn't see that. Thanks for the heads up.

 

[takeurmeds02]

I'll just answer it here. But essentially, Pyruvate is made into Oxaloacetate in the cytosol. Since the outer mitochondrial membrane is almost freely permeable to most things in the cytosol, Oxaloacetate is also present in the inner membrane space of the mitochondria. The cell then oxidizes an NADH and couples this to the reduction of Oxaloacetate to Malate. Malate is then transported across the inner mitochondrial membrane. Once malate is across, it oxidizes back to oxaloacetate coupled to the reduction of NAD+. There are also other processes that could take place but this is probably the preferred mechanism.

Look up "Malate-Aspartate shuttle"

Concurrently, another Pyruvate is made into acetyl-coA which is shuttled across the membrane during production.

While in the Mitochondria, oxaloacetate and acetyl-coA are combined to make citrate and continue on in the TCA pathway.