Oxidative Phosphorylation | Definition , Steps & Examples

By | November 12, 2019

Oxidative Phosphorylation

Oxidative Phosphorylation Definition

What is Oxidative phosphorylation: It is basically the synthesis of ATP by phosphorylation of ADP due to which energy is gained by electron transport chain and which takes place in the mitochondria in the process of Aerobic respiration.

Where does Oxidative Phosphorylation occur:

Oxidative phosphorylation occurs in the mitochondria. It is basically the synthesis of ATP by phosphorylation of ADP due to which energy is gained by an electron transport chain and which takes place in the mitochondria in the process of Aerobic respiration.

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Electron Transport Chain and Oxidative Phosphorylation:

The electron transport chain is a series of proteins that transfer electrons in the inner membrane of mitochondria. The electrons pass from one membrane to another in a series of redox reactions. In these reactions, the released energy is captured as gradient proton that is used in the making of ATP in a process called Chemiosmosis. The electron transport chain and chemiosmosis together make Oxidative Phosphorylation. The majority of ATP synthesis occurs in mitochondria in the process of Oxidative Phosphorylation. Even plants generate ATP in chloroplasts by phosphorylation.

Steps of Oxidative Phosphorylation:

The steps used for the process of Oxidative Phosphorylation are:

  • Delivery of electrons by NADH and FADH2:

From other steps of cellular respiration, reduced electrons carriers (NADH and FADH2) transfer their electrons to molecules near the beginning of the electron transport chain. They turn back into NAD+ and FAD that can be reduced in other steps of cellular respiration.

  • Electrons transfer and proton pumping:

The electrons then move from a higher to lower energy level by releasing energy. Some of the energy used to pump H+ ion, move out from the matrix and transfer into intermembrane space. This pumping process establishes an electrochemical gradient.

  • Splitting of oxygen to form water:

Then electrons transfer to molecular oxygen which split in half and takes H+ to form water.

  • Gradient-driven synthesis of ATP:

H+ ions flow down their gradient and turn back to the matrix and pass through an enzyme known as ATP synthesis, which harnesses the flow of protons to ATP synthesis.

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The Electron Chain Transport Within Oxidative Phosphorylation:

The oxidative transport chain is linked with electron transport. The electron transport system lies in the inner membrane of mitochondria which transfers electrons by reduced electron carriers NADH and FADH2 through a series of electron acceptors. Movement of electrons through electron system “charges” a battery that is used to make ATP in Oxidative Phosphorylation. The oxidation of fatty acid and sugar form couple to ATP synthesize and extract energy from food.

Oxidative Phosphorylation Within Cellular Respiration:

It produces the basic energy currency of the cell that needs the function of ATP. It is the fourth step of cellular respiration which produces the most energy. It fit into cellular respiration here:

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