AP BIOLOGY

Detailed explanation-1: -The Krebs cycle itself actually begins when acetyl-CoA combines with a four-carbon molecule called OAA (oxaloacetate) (see Figure above). This produces citric acid, which has six carbonatoms.

Detailed explanation-2: -Acetyl-CoA is a metabolite derived from glucose, fatty acid, and amino acid catabolism.

Detailed explanation-3: -Products and Functions of the Krebs Cycle For one cycle, two molecules of carbon, three molecules of NADH, one molecule of FADH2 and one molecule of ATP or GTP are produced. Each glucose molecule produces two molecules of acetyl CoA, enough for two cycles.