Final answer:
ATP from oxidative phosphorylation is synthesized in the mitochondrial inner membrane, where the electron transport chain and ATP synthase are located.
Step-by-step explanation:
ATP from oxidative phosphorylation is synthesized in the mitochondrial inner membrane. This is because oxidative phosphorylation involves the electron transport chain and chemiosmosis, processes that occur specifically in the inner membrane of the mitochondria in eukaryotic cells. Electrons are passed through a series of electron carriers embedded in the inner membrane, creating a proton gradient across this membrane. The energy from this gradient is harnessed by ATP synthase, also located in the inner membrane, to convert ADP into ATP in the presence of oxygen. The inner membrane's extensive folds, known as cristae, increase its surface area, facilitating more ATP synthesis.