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So this is where the big guns are taken out, this is were 32 of the 36 ATP molecules are produced. The electron transport chain also occurs in the mitochondria, however, it doesn't occur in the matrix it takes place in the inner mitochondrial membrane and cristae membranes.
These membranes have carriers within them, which have the property of being easily reduced and oxidized. So that's kind of neat. For the sake of simplicity all of these carriers are known as cytochromes, except for CoEnzyme Q. The electrons are passed along the electron chain from one carrier to another, due to an increasing electronegativity.
The electrons that are passed down this chain are donated by our electron carriers NADH and FADH2.
FADH2 enters the electron chain at a later stage, and the does not produce as much ATP.
Each NADH molecule will produce 3 ATP molecules
Each FADH2 molecule will produce only 2 ATP molecules
As the electrons are passed along the chain they lose energy. Oxygen is the last electron acceptor, this is due to it's relatively high electron negativity. Thai oxygen molecule then bonds with two hydrogen atoms to form water.
As the electrons are passed along they release energy. This energy is used to pump hydrogen ions out of the matrix into the intermembrane space. This results in a very concentrated area of hydrogen ions in this intermembrane space.
This process involving the movement of hydrogen ions is called chemiosmosis.
These hydrogen ions then want to move from this high concentration back to into the matrix, however they can only do so through ATP synthase. The hydrogen ions passively move through this channel (facilitated diffusion). As they move through the channel the enzyme uses this energy to phosphorylate ADP to ATP. This type if phosphorylation is called oxidative phosphorylation, because it utilizes the electron transport chain.
And thus ends our journey through cellular respiration. Up next. Photosynthesis. Yup. There's more.
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