Oxidative Phosphorylation

Oxidative Phosphorylation

For students who have asked for the definition of Oxidative phosphorylation:

Oxidative phosphorylation (or OXPHOS in short) is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing energy which is used to reform ATP. In most eukaryotes, this takes place inside mitochondria. Almost all aerobic organisms carry out oxidative phosphorylation. This pathway is probably so pervasive because it is a highly efficient way of releasing energy, compared to alternative fermentation processes such as anaerobic glycolysis.

Watch this video to know more about Oxidative Phosphorylation and the Electron Transport Chain:

Oxidative Stress

Oxidative Stress

Oxidative stress is an imbalance between the production of free radicals and the ability of the body to counteract or detoxify their harmful effects through neutralization by antioxidants.

What are free radicals?

A free radicals is an oxygen containing molecule that has one or more unpaired electrons, making it highly reactive with other molecules.

Oxygen by-products are relatively unreactive but some of these can undergo metabolism within the biological system to give rise to these highly reactive oxidants. Not all reactive oxygen species are harmful to the body. Some of them are useful in killing off invading pathogens or microbes.

Free radicals can chemically interact with cell components such as DNA, protein or lipid and steal their electrons in order to become stabilized. This, in turn, destabilizes the cell component molecules which then seek and steal an electron from another molecule, therefore triggering a large chain of free radical reactions and oxidative stress.

What are antioxidants?

Every cell that utilizes enzymes and oxygen to perform functions is exposed to oxygen free radical reactions that have the potential to cause serious damage to the cell. Antioxidants are molecules present in cells that prevent these reactions by donating an electron to the free radicals without becoming destabilized themselves. An imbalance between oxidants and antioxidants is the underlying basis of oxidative stress.

Damaged caused by oxidative stress

Much of the damage caused by oxidative stress arises from its modification of the DNA inside a cell’s nucleus which gives rise to mutations.

Examples of the conditions caused by free radical damage include:

  • Neurodegenerative disorders such as Parkinson’s disease, multiple sclerosis and Alzheimer’s disease
  • Mutagenesis and cancer
  • Heart and blood vessel disorders such as heart failure, heart attacks, atherosclerosis and cardiac ischemia
  • Lung conditions such as emphysema and lung cancer
  • Chronic fatigue syndrome
  • Cataracts and vision disorders such as retrolental fibroplasia
  • Arthritis and inflammatory disease
  • Diabetes
  • Kidney disease
  • Pancreatitis
  • Gut disorders such as inflammatory bowel disease
  • Skin lesions such as those caused by sun damage
  • Lipoprotein oxidation in new-borns
  • Failure of organ transplant
  • Frostbite
  • Haemolytic anaemia, protoporphyrin, photo oxidation
  • Autoimmune diseases