Electron Transport Chain

Electron Transport Chain

Remember from earlier the products produced

·         Reduced NAD

·         Reduced FAD

Both of these are co-enzymes.                

The electron transport chain is the mechanism by which the energy from electrons within the  hydrogen atoms is converted into a form that the cells can us, namely ATP

The Electron Transport Chain and Mitochondria

Attached to the inner folds of the mitochondria membrane or cristae are the enzymes and other proteins involved in the electron transport chain and hence is the site of ATP synthesis.  

The Electron Transport Chain and Mitochondria

1.       The Hydrogen atoms produced during Glycolysis and the kerbs cycle combine with the coenzymes NAD and FAD to form reduced versions of themselves

2.       The Reduced NAD and FAD donate the electrons of the hydrogen molecules that they are carrying to the first molecule of the electron transport chain.

3.       This releases the protons from the hydrogen atoms which are then actively transported across the inner mitochondrial membrane

4.       The electron meanwhile is passed along a chain of electron transport carrier molecule in a series of oxidation-reduction reactions. As the electrons are passed down they release energy which is used to combine ADP and Pi to make ATP  

5.       The protons accumulate in the space between the mitochondrial membranes before they diffuse back into the mitochondrial matrix through specific protein channels.

6.       At the end of the chain the electrons combine with these protons and oxygen to form water.

This means that oxygen is therefore the final acceptor of electrons in the electron transport chains.

Remember that there are 3 different molecules that carry the electrons in the electron transport chain before oxygen finally accepts it electrons.

Oxygen is Important !

Without it the final hydrogen carrier cannot be removed from the end of the electron transport chain. If this did not happen then the electrons would back up  along the chain and the process of aerobic respiration would stop.

Cyanide

Cyanide is a non-competitive inhibitor for the final enzyme in the electron transport chain. This is the enzyme that catalyses the addition of hydrogen ions and electrons to oxygen to from water

As a result respiration cannot occur.