Final answer:
Most ATP in eukaryotic cells is produced by oxidative phosphorylation, a process that occurs in the mitochondria and is responsible for the majority of ATP synthesis during glucose catabolism.
Step-by-step explanation:
In an eukaryotic cell, most of the ATP derived from glucose during cellular respiration is produced by a process known as oxidative phosphorylation. This process occurs in the mitochondria, often referred to as the cell's "powerhouses" or "energy factories," because they make adenosine triphosphate (ATP), the cell's main energy-carrying molecule.
Oxidative phosphorylation involves the transfer of electrons through a series of protein complexes and associated mobile electron carriers known as the electron transport system (ETS). As electrons move down the ETS, they create a proton gradient across the mitochondrial membrane that drives the synthesis of ATP through chemiosmosis, which is responsible for producing about 90 percent of the ATP during glucose catabolism. This process requires oxygen, hence the term oxidative, and it adds a phosphate group to ADP to form ATP, hence phosphorylation.