Stupid Question

[osimsDDS]

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quick stupid question:

does pyruvate decarboxylation account for the krebs cycle? because it forms 2 CO2 molecules and usually i know that krebs usually forms 4 CO2 molecules but in cliffs ap bio it says krebs forms 2 CO2 molecules so im wondering if they just join pyruvate decarboxylation with the krebs cycle...thanks

 

[PooyaH]

quick stupid question:

does pyruvate decarboxylation account for the krebs cycle? because it forms 2 CO2 molecules and usually i know that krebs usually forms 4 CO2 molecules but in cliffs ap bio it says krebs forms 2 CO2 molecules so im wondering if they just join pyruvate decarboxylation with the krebs cycle...thanks

hmm pyruvate decarboxylation happens in the mitochondrial matrix and glycolysis takes place in the cytoplasm, so I'd say it would account for the krebs cycle more than glycolysis, but I'm not 100% sure!

 

[Predentole]

From what I know, it doesn't account for pyruvate decarboxylation. Pyruvate decarbox starts when acetyle-CoA kicks in. Cliff's bio does say the Kreb's cycle forms 2 carbon dioxides, but it undergoes two turns so it forms 4 total.

 

[osimsDDS]

From what I know, it doesn't account for pyruvate decarboxylation. Pyruvate decarbox starts when acetyle-CoA kicks in. Cliff's bio does say the Kreb's cycle forms 2 carbon dioxides, but it undergoes two turns so it forms 4 total.

No cliffs says 1CO2 per pyruvate so thats 2 for 1 glucose molecule...

 

[Predentole]

Yeh it's 1 CO2 per pyruvate during pyruvate decarbox. But in the Kreb's cycle it says 2 CO2, and theres 2 turns so the Kreb's cycle makes a total of 4 CO2 and the 2 CO2 from pyruvate decarbox doesn't do anything with the kreb's cycle.

 

[hdu]

Let's count the Carbons and CO2 molecules...

Pyruvate decarboxylation

Pyruvate (3 carbons) is decarboxylated to Acetyl Co A (2 carbons in the acetyl group) + CO2

The acetyl group of Acetyl Co A (two carbons) is oxidized completely in the Krebs cycle to 2 CO2 +H2O


So:
Glucose (6 Carbons) to 2 pyruvate (3 Carbons each)

2 Pyruvate (2 x 3 carbons) to 2 acetyl coA (2 x 2 C) + 2 CO2

2 Acetyl CoA to 2 CO2 each (2 x 2 CO2 = 4 CO2) in the Krebs cycle


At the end, the 6 carbons of glucose have been oxidized to 6 CO2 (two of them produced in the decarboxylation of the 2 piruvate, and 4 produced in the oxidation of the 2 acetyl groups of Acetyl CoA).

I hope it helps

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