Follow a glucose molecule through aerobic respiration until all the energy that can be extracted is ...

Respiration starts with glycolysis. During this process, the 6carbon glucose is phosphorylated and oxidized into two 3carbon sugar phosphates and eventually to two 3carbon acids (pyruvates). Two ATPs are used in this process and four are produced for a net yield of two ATPs per glucose. The oxidations are coupled with the reductions of NAD+ to NADH. Each pyruvate is further oxidized to CO2 and acetylCoA, which can enter the Krebs cycle. This oxidation is also coupled with the reduction of NAD+ to NADH. In the Krebs cycle, acetylCoA donates its 2carbon fragment to the 4carbon acid, oxaloacetate to form the 6carbon acid, citrate. Citrate is oxidized to a 5carbon acid with the release of CO2 and the 5carbon acid is oxidized to a 4carbon acid with the release of another CO2 . The oxidations are coupled with the reductions of cofactors (NAD+ or FAD). One ATP is produced for each acetylCoA that enters the cycle. The 4carbon acid is converted to oxaloacetate, and the cycle can start again. At this point, all the carbons in the original glucose have been converted to CO2 . The reduced cofactors from glycolysis and the Krebs cycle are sent to electron transfer chains where they are oxidized. The energy released by these oxidations is used to produce more ATP.