Electron Transport Chain _ETC

Electron Transport Chain _ETC
Energy-rich molecules, such as glucose, are metabolized by a series of
oxidation reactions ultimately yielding Co2and water. The
metabolic intermediates of these reactions donate electrons to specific
coenzymes ( NAD+,FAD) and The reduced form of these coenzymes ( NADH,FADH2) can, in turn, each donate a pair of electrons to a specialized set of electron carriers, collectively called the electron transport chain, as electrons are passed down the electron transport chain, they lose much of their free energy. Part of this energy can be captured and stored by the production of ATP from ADP and inorganic phosphate (Pi). This process is called oxidative phosphorylation. The remainder of the free energy that not trapped as ATP is released as heat. It (ETC) all happens in or at the inner mitochondrial membrane.
Organization of the chain
The inner mitochondrial membrane can be divided into five separate enzyme complexes, called complexes I, II, III, IV, and V.
Complexes I to IV each contain part of the electron transport chain, whereas complex V catalyzes ATP synthesis as figure below reveals.

Each complex accepts or donates electrons to relatively mobile electron carriers, such as coenzyme Q and cytochrome c. Each carrier in the electron transport chain can receive electrons from an electron donor, and can subsequently donate electrons to the next carrier in the chain. The electrons ultimately combine with oxygen and protons to form water. These complexes are:
Complex I; NADH-CoQ reductase (NADH dehydrogenase complex)