TCA Anaplerotic Reactions and Electron Transport Chain

Oxidative Phosphorylation

The energy released from glucose oxidation is captured in the form of NADH and FADH2. They can then be oxidized by the electron transport chain through a series of redox reactions ending with O2 as the final acceptor of their electrons. This results in release of large quantities of energy that is harnessed for the synthesis of ATP in the process mentioned above.

Electron Transport Chain

Series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously). There is coupling of this electron transfer with the transfer of protons (H+ ions) across a membrane. The electrons that transferred from NADH and FADH2. Many of the enzymes are membrane bound.

Complexes of ETC

Are arranged in order of decreasing electronegativity of standard redox potential.

1. When NADH is the electron donor, there are three points in the ETC where there is large enough change in standard redox potential and sufficient energy to drive the synthesis of an ATP molecule. NADH- CoQ, - cytc, - O2.

2. When FADH2 is the donor, there is only 2 points. Coq- cytc, - O2.

Chemiosmosis. The energy coupling mechanism

The energy released when electrons are passed down the electron transport chain, is used to pump H+ from the mitochondrial matrix to the inter-membrane space. H+ then moves down its concentration gradient back across the membrane, passing through the protein complex ATP synthase.