Oxidative Phosphorylation (AQA A Level Biology): Revision Note
Exam code: 7402
Aerobic respiration: oxidative phosphorylation
Oxidative phosphorylation is the final stage of aerobic respiration
It takes place on the cristae of the inner mitochondrial membrane
It relies on proteins embedded in the membrane, e.g. ATP synthase enzymes
The large surface area of the folded cristae provides many locations for oxidative phosphorylation to occur

During oxidative phosphorylation:
hydrogen atoms are donated by reduced NAD and reduced FAD from the Krebs cycle
hydrogen atoms split into protons (H+ ions) and electrons
the electrons enter the electron transport chain; energy is released as they pass between electron carriers
The electron transport chain is made up of electron carrier proteins that are embedded in the inner mitochondrial membrane
the released energy is used to actively transport protons across the inner mitochondrial membrane from the matrix into the intermembrane space
the protons move down their concentration gradient back to the matrix by facilitated diffusion; they move via proton channels that are associated with ATP synthase
This movement of protons is known as chemiosmosis
ATP synthase catalyses the formation of ATP from ADP and Pi
At the end of the electron transport chain the electrons pass to oxygen, which acts as the final electron acceptor
Oxygen combine with protons and electrons at the end of the electron transport chain to form water as a waste product

Examiner Tips and Tricks
Remember that oxidative phosphorylation produces ATP; you should never say that energy is produced.
Make sure that you understand the role of oxygen in oxidative phosphorylation; it acts as a final electron acceptor, allowing the electron transport chain to continue functioning normally.
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