AP BIOLOGY

Detailed explanation-1: -The cycle harnesses the available chemical energy of acetyl coenzyme A (acetyl CoA) into the reducing power of nicotinamide adenine dinucleotide (NADH). The TCA cycle is part of the larger glucose metabolism whereby glucose is oxidized to form pyruvate, which is then oxidized and enters the TCA cycle as acetyl-CoA.

Detailed explanation-2: -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-3: -The final step of the Krebs cycle regenerates OAA, the molecule that began the Krebs cycle. This molecule is needed for the next turn through the cycle. Two turns are needed because glycolysis produces two pyruvic acid molecules when it splits glucose.

Detailed explanation-4: -As stated above, this cycle results in the final oxidative steps of acetyl groups, resulting in the release of two molecules of carbon dioxide gas. The citric acid cycle further yields reduced coenzymes with each oxidative step; these coenzymes include NADH, GTP, and FADH2.