AP BIOLOGY

Detailed explanation-1: -Fuel for the Krebs cycle comes from lipids (fats) and carbohydrates, which both produce the molecule acetyl coenzyme-A (acetyl-CoA). This acetyl-CoA reacts in the first step of the eight step sequence of reactions that comprise the Krebs cycle, all of which occur inside mitochondria of eukaryotic cells.

Detailed explanation-2: -The two-carbon acetyl-CoA that is the “fuel” for the TCA cycle can be generated by several metabolic pathways including glucose metabolism, fatty acid oxidation, and the metabolism of amino acids.

Detailed explanation-3: -Before these rather large molecules can enter the TCA cycle they must be degraded into a two-carbon compound called acetyl coenzyme A (acetyl CoA). Once fed into the TCA cycle, acetyl CoA is converted into carbon dioxide and energy.