ATP is produced in each stage of cellular respiration, but the majority is generated during the electron transport chain and chemiosmosis, which together are known as oxidative phosphorylation. The ATP production in this final phase depends on NADH and FADH₂, with three ATP molecules typically generated for every oxidized NADH molecule and two ATP molecules for every oxidized FADH₂ molecule. Overall, the complete oxidation of one glucose molecule can yield up to 38 ATP molecules.
In cellular respiration, the production of ATP occurs in each stage of the process. However, the majority of ATP is produced during the electron transport chain and chemiosmosis, which are collectively known as oxidative phosphorylation. During this final phase, the electron transport chain uses the energy from NADH and FADH₂ to create a proton gradient across a membrane. This gradient is then used to synthesize ATP through a process called ATP synthesis or ATP synthase.
The ATP production during the electron transport chain varies depending on the source of electrons. For every oxidized NADH molecule, approximately three ATP molecules are produced. However, for every oxidized FADH₂ molecule, only about two ATP molecules are produced. The difference in ATP production is due to the starting points of the electrons in the electron transport chain.
Overall, when considering all three stages of cellular respiration, the complete oxidation of one glucose molecule can result in the production of up to 38 ATP molecules, with the majority of ATP being produced during the electron transport chain and chemiosmosis.