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Krebs Cycle Question

Hi, I just have a quick question for anyone. I have been reading my physiology textbook and am confused. For anyone who can help me out:

Are the acetyl groups in the krebs cycle derived from fatty acids? i know they are derived from pyruvic acids, but am unclear about fatty acids?

Yes…they are derived from fatty acids…

In the mitochondria, pyruvate and fatty acids are used to construct Acetyl CoA…


I thought pyruvate and pyruvic acids were the end products from metabolizing glucose in the first stage of ATP production (Glycolysis I think). I could be totally wrong though, it’s been a couple years since I took a biology course.

Thanks Mufasa.

The acetyl groups used for acetyl CoA can come from both glucose and triglycerides.

Very simply:

Glycolysis produces pyruvic acid from gulcose, and pyruvic acid becomes acetyl CoA after it is decarboxylized (loses CO2) and oxidized (loses H ions).


Glycerol from triglycerides is converted to glyceraldehyde 3-phosphate, which, if ATP supply is high in a cell, becomes glucose. If ATP supply is low, glyceraldehyde 3-phosphate is catabolized to pyruvic acid. Pyruvic acid can then be converted to acetyl CoA.


Fatty acids from triglycerides undergo beta-oxidation, which is simply the removal of two carbon atoms at a time from a fatty acid chain. The two carbons link with coenzyme A, forming acetyl CoA.

…hope this helps

Gotta love Biochemistry.

Jeez, I did this last year (junior year of high school) and dont remember shit. The names are familiar, but thats about it.

How do you guys remember/know this?

I read about it in my Anatomy/Physiology textbook about a week ago :slight_smile: