OXIDATIVE PHOSPHORYLATION, ELECTRON TRANSPORT CHAIN

• It is the main source of energy of our cell.
• Takes place in Mitochondria.
• Movement of protons through inner mitochondrial membrane leads to ATP production

Oxidative phosphorylation includes the coupling of the oxidation of NADH or FADH2 by the respiratory chain with the synthesis of ATP via gradient of protons across the inner mitochondrial membrane.

An electron transport chain consists of a properly arranged & oriented set of electron carriers transporting electrons in a specific sequence from a reduced nicotinamide coenzyme (NADH) or a reduced flavin prosthetic group (FADH2) to molecular O2.

The inner mitochondrial membrane carries an electron transport chain called the mitochondrial respiratory chain, which forms the final path for electron flow from tissue substrates to molecular O2.

At each step, electrons flow from the reluctant of a redox couple, having a lower redox potential to the oxidant of another redox couple possessing a higher redox potential.

The free energy, liberated during the transmitting of electrons along the chain, is used in forming high-energy bonds of ATP.

The sequence of reactions whereby the reduced forms of the coenzymes are reoxidized by molecular O2 known as electron transport chain

The chain has principle electron carriers

Each of them functions as a redox system with its prosthetic group or metal ions changing alternatively to reductant and oxidant – forms during electron transport.

To administrate electron transport chain in mitochondria inner membrane four complex presents separately.

It transfers reducing equivalents (I.e. H+ and e) from NADH to CoQ through its FMN and iron-sulfur clusters, oxidizing NADH and reducing CoQ.

It transports clusters directly to CoQ from succinate through its FAD, cytochrome v560 and iron-sulfur clusters