AP BIOLOGY

Detailed explanation-1: -A 6-carbon glucose molecule is split into two 3-carbon molecules called pyruvates. Pyruvate is needed in order to create acetyl CoA. This is a very short step in between glycolysis and the citric acid cycle.

Detailed explanation-2: -The first is glycolysis, the pathway responsible for breaking down glucose into pyruvate. The two pyruvate molecules from each glucose then enter the citric acid cycle, which releases the energy within the pyruvates by breaking them down into inorganic molecules.

Detailed explanation-3: -In the presence of oxygen, the next stage after glycolysis is oxidative phosphorylation, which feeds pyruvate to the Krebs Cycle and feeds the hydrogen released from glycolysis to the electron transport chain to produce more ATP (up to 38 molecules of ATP are produced in this process).

Detailed explanation-4: -However, before the citric acid cycle can begin, acetyl CoA must be produced. Acetyl CoA is created from pyruvate (the end product of glycolysis) during pyruvate oxidation. Pyruvate oxidation results in one molecule of acetyl CoA, one molecule of carbon dioxide, and one molecule of NADH.

Detailed explanation-5: -Summary. In the presence of oxygen, pyruvate is transformed into an acetyl group attached to a carrier molecule of coenzyme A. The resulting acetyl CoA can enter several pathways, but most often, the acetyl group is delivered to the citric acid cycle for further catabolism.