Oxidative Phosphorylation

Oxidative Phosphorylation is the last step during cellular respiration, and it is a process of ATP formation that occurs in mitochondria. It occurs when electron carriers transfer the electrons from FADH₂ or NADH to oxygen. Oxidative phosphorylation is linked to the process of the electron transport chain which is in the inner mitochondrial membrane. In this article, we will read about Oxidative Phosphorylation, its steps, stages, diseases, and disorders related to Oxidative Phosphorylation, and much more.

Oxidative Phosphorylation Definition

Oxidative phosphorylation is a type of metabolic process that produces adenosine triphosphate (ATP). It’s also known as the electron transport chain (ETC).

What is Oxidative Phosphorylation?

The process by which electron carriers transfer electrons from NADH and FADH₂ to oxygen is known as oxidative phosphorylation. The goal is to create ATP. Electrons go through several redox reactions during this process. An essential phase in the synthesis of energy is oxidative phosphorylation. It takes place in the mitochondria. It includes processes including oxygen splitting, proton pumping, electron delivery, electron transport, and ATP synthesis. Certain inhibitors, including rotenone, can impede oxidative phosphorylation. Oxidative phosphorylation is an issue that can lead to illnesses like cancer.

Steps of Oxidative Phosphorylation

Oxidative Phosphorylation steps are:

1. Electron Delivery: NADH and FADH₂ are reduced and they transfer their electrons to the molecules that are at the beginning of the transfer chain.
2. Electron Transport and Proton Pumping: Electrons move from a high energy level to a low energy level and release energy. Some of that energy will be used to generate an electric charge when electrons are pushed from one end of the membrane to the other. An electrochemical gradient is created due to pumping.
3. Oxygen Splitting: Electron reacts with a half-split oxygen molecule at the end of ETC. H⁺ is taken up to form water.
4. ATP Synthesis: Through an ATP synthase enzyme, H⁺ ions are sent back up to the mitochondria. It helps in ATP synthesis by controlling the flow of protons.

Stages of Oxidative Phosphorylation

Oxidative Phosphorylation has two stages: chemiosmosis and electron transport chain (ETC).

Chemiosmosis

ATP synthesis is an endergonic process whereas the flow of electrons through the electron transport chain is an exergonic process. These processes happen within the membrane. By the movement of proteins, the energy will be transmitted from the electron transport chain to ATP synthase.

Electron Transport Chain

A sequence of events that take place within the walls of mitochondria make up the electron transport chain. By releasing energy gradually as opposed to all at once, it helps keep the cells from becoming unstable. This is how the process of oxidative phosphorylation in cells produces energy effectively and under control. An enormous quantity of energy is unleashed.

Factors Affecting Oxidative Phosphorylation

There are several factors that affects oxidative phosphorylation.

Inhibitors: There are certain chemicals, which have an effect on the oxidation phosphorylation process.

Type	Mechanism	Inhibitor
Respiratory Chain Inhibitor	Inhibit electron transfer from NADH to CoQ Prevent electron transport between Cytb and Cytc1 Inhibit cytochrome oxidase	Barbital Dimercaptopropanol
Oxidative Phosphorylation Inhibitor	Prevent hydrogen ions from returning when combined with F0 unit of ATP synthase and lead to incomplete phosphorylation and prevention of Oxidative Phosphorylation	Oligomycin Dicyclohexylcarbodiimide

• Uncoupling Agent: The electron transfer and ATP synthesis process is separated by agents such as 2,4-dinitrophenol (DNP). It prevents ATP formation and doesn’t change electron transport which causes the energy to be converted into heat
• ADP Control: ADP controls the rate at which Oxidative Phosphorylation occurs. When additional ATP is needed and the ADP level is not sufficient, there is a slowing of the rate.
• Thyroid Hormone: The thyroid hormone speeds up the breakdown of ATP by initiating a process. It produces more heat by speeding up the process of oxidative phosphorylation.
• Mitochondrial DNA Mutation: Mutations in mitochondrial DNA can affect Oxidative Phosphorylation. It reduces ATP levels and causes a variety of diseases.
• Environmental Factors: An Oxidative Phosphorylation can be influenced by toxins, pollutants, drugs and changes in the availability of nutrients. In cellular metabolism, environmental factors play a role.

Diseases and Disorders Related to Oxidative Phosphorylation

Sometimes Oxidative Phosphorylation may result in disease , few of which are discussed below:

• Hypotonia : Impaired oxidative phosphorylation may result to insufficient energy generation in muscles, causing to muscular weakness and hypotonia.
• Ophthalmoplegia : Ophthalmoplegia is a common result of mitochondrial illnesses that damage the muscles that govern eye movement.
• Cancer : Mitochondrial malfunction may contribute to the development of cancer by altering cellular energy metabolism and encouraging genomic instability.
• Muscle weakness : Generalised muscular weakness can be caused by oxidative phosphorylation abnormalities leading to inadequate ATP generation.
• Severe Constipation : Impaired motility brought on by mitochondrial dysfunction in the gastrointestinal muscles can result in extremely severe constipation.
• Cardiomyopathy : Cardiomyopathy is a condition where the heart’s ability to pump blood is compromised by inadequate energy production in the heart muscle as a result of oxidative phosphorylation abnormalities.

Conclusion – Oxidative Phosphorylation

Oxidative phosphorylation is the method by which ATP is synthesised from NADH and FADH₂.

• It is a crucial process that takes place in mitochondria and involves a number of processes including oxygen splitting, transport, proton pumping, electron delivery, and ATP production.
• Inhibitors like rotenone, uncoupling agents like 2,4-dinitrophenol, thyroid hormone, ADP control, mitochondrial DNA mutations, and environmental factors including dietary availability and pollutants can all have an impact on oxidative phosphorylation.
• Gene mutations affecting oxidative phosphorylation can have detrimental implications, especially in cases of mitochondrial diseases.

FAQs – Oxidative Phosphorylation

What is Oxidative Phosphorylation?

Oxidative Phosphorylation is a process of cell respiration in which electrons from NADH or FADH₂ come into contact with O₂ to synthesize ATP from ADP.

What is the Function of Oxidative Phosphorylation?

Oxidative Phosphorylation is essential in synthesis of ATP which are used by high animal and plant species to support life and function as a regulator of metabolism homeostasis.

What are the Steps of Oxidative Phosphorylation?

The Oxidative Phosphorylation involves the following steps: electron delivery, electron transport and proton pumping, oxygen splitting, and ATP synthesis.

What is the End product of Oxidative Phosphorylation?

ATP and H₂0 are the end products of the oxidative phosphorylation.

What are the two Stages of Oxidative Phosphorylation?

The Oxidative Phosphorylation has two stages: Electron transport chain (ETC) and Chemiosmosis.

What is the difference between Oxidative and Non Oxidative Phosphorylation?

Oxidative phosphorylation is a biological activity which takes place on the inner mitochondrial membrane. Non-cyclic photophosphorylation occurs in chloroplasts on the thylakoid membrane.

What is the difference between the Electron Transport Chain and Oxidative Phosphorylation?

The ETC is a collection of proteins that move electrons from donors to acceptors. The mechanism that creates ATP with the energy produced by these electrons is called oxidative phosphorylation.

Why is ETS called Oxidative Phosphorylation?

Electron transport system (ETS) is known as oxidative phosphorylation because it employs the electrochemical gradient formed by the electron transport chain to convert ADP to ATP.

How many ATP are Produced in Oxidative Phosphorylation?

Electrons from NADH and FADH2 are subsequently transported to molecular oxygen, where they are connected to the synthesis of an extra 32 to 34 ATP molecules via oxidative phosphorylation.