Carbohydrate Metabolism: Electron Transport Chain & Oxidative Phosphorylation Flashcards
What are the products from glycolysis and citric acid cycle that are used in the ETC?
10 NADH (each converts to 3 ATP) 2 FADH2 (each converts to 2 ATP's, because their electrons are at a lower energy level than NADH)
Where does the ETC occur?
On the matrix-facing surface of the inner mitochondrial membrane
What is the big idea of the ETC?
NADH and FADH2 donate electrons to the chain via oxidation (OIL RIG) which are passed down from one complex to the next. Reduction potentials increase down the chain, until the electrons end up on the oxygen, which has the higher reduction potential. The movement to lower energy states release energy and pumps protons across the membrane.
What does Complex I do in the ETC?
responsible for the transfer of electrons from NADH to coenzyme Q to form CoQH2 (4 protons are moved across)
What does Complex II do?
transfers electrons from succinate to CoQ
No protons are pumped across here
What does complex III do?
facilitates the transfer of electrons from CoQ to cytochrome C through the oxidation and reduction of cytochromes (proteins where iron is reduced to Fe2+ and reoxidizes to Fe3+). The Q-cycle shuttles 4 electrons across the membrane.
What does complex IV do?
transfers electrons from cytochrome C to oxygen
Why are different amounts of ATP produced for different cells?
Because NADH cannot cross the inner-mitochondrial membrane, so it must use one of two shuttle mechanisms to transfer it’s electrons to energy carriers in the mitochondrial matrix. The different shuttles result in different amounts of ATP production.
The shuttles are:
glycerol 3-phosphate shuttle
malate-aspartate shuttle
What is oxidative phosphorylation?
After the ETC pumps across many protons, there is an electrochemical gradient generate (proton-motive force). This gradient stores energy and can be used to form ATP via chemiosmotic coupling.
