Most of the free energy released during the oxidation of glucose to CO₂ is retained in the reduced co-enzyme NADH and FADH₂, generated during the kreb's cycle.
Electron are released from these co-enzymes and are eventually transferred to an oxygen molecule to form water.
These transfer of electron from co-enzymes to oxygen molecule occurs through a series of protein complexes in the mitochondrial membrane. And the process is termed as Electron Transport Chain.
The large amount of free energy is released during the oxidation of NADH and FADH₂ is used in the production of ATP
