Krebs Cycle Question

Nutrition
1

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?

2

Yes…they are derived from fatty acids…

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

Mufasa

3

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.

4

Thanks Mufasa.

5

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).

or

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.

and

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

6

Gotta love Biochemistry.

7

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?

8

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