Explain the concept of 'chemiosmosis' in oxidative phosphorylation

The process of chemiosmosis essentially addresses the issue of storing chemical energy into a specific bond. The conversion from chemical energy in the coenzymes, such as NADH and FADHto ATP cannot occur directly. Therefore energy from, NADH -> NAD+ + H+ + 2e- to phosphorylate ADP + Pi -> ATP, must be transferred through chemiosmosis.  What is chemiosmosis? Chemiosmosis is very similar to osmosis which takes place with water moving through semipermeable membranes down its concentration gradient. The difference, of course, explaining the reason for 'chemi-' is that it involves ions moving down an electrochemical gradient.  Inside the electron transport chain, referring to the initial equation, the electrons 'unloaded' undergo reduction-oxidation reactions to actively transport H+ ions to the intermembrane space. This creates an electrochemical gradient. Electro- denoting the difference in charge, and chemical signifying the differences in concentration. This gradient means that H+ diffuses down through selective channels which contain ATP synthase into the matrix, this movement of ions produces kinetic energy that is required to drive the formation of ATP (which is energetically unfavourable). Oxygen acts as the final electron acceptor - reacting with H+ to form water, this maintains the H+ electrochemical gradient required for chemiosmosis. 

Answered by Narut P. Biology tutor


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