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Electrons are released when chemical bonds are broken - Chemiosmosis?! [PLEASE HELP]

I have the Oxford A-level Year 2 book.
It says

Electrons are raised to higher energy levels / or excited in two ways :

- High energy electrons are released when chemical bonds are broken in respiratory substrates (e.g. glucose)

This doesn't make chemical sense. You can't release electrons by breaking down compounds.


Can someone explain this?
Reply 1
Original post by mphysical
That is how batteries work.


Please expand.
Original post by nwmyname
I have the Oxford A-level Year 2 book.
It says

Electrons are raised to higher energy levels / or excited in two ways :

- High energy electrons are released when chemical bonds are broken in respiratory substrates (e.g. glucose)

This doesn't make chemical sense. You can't release electrons by breaking down compounds.


Can someone explain this?


Have you ever studied respiration? It's quite a long process :P The basic premise of it is glucose undergoes a load of enzyme-driven reactions to form NADH and FADH2. These are reducing agents, which means they donate electrons. Now, I can't really remember much from chemistry, but as you know, covalent bonds are made up of shared electrons, so if you break a bond and reform it on another molecule then the electrons are going to be transferred with it. So what happens is that these reducing-agents donate a hydrogen and 2 electrons to the protein complexes in the mitochondrial membrane. These protein complexes then undergo similar redox reactions, with each subsequent complex at a lower energy than the one before it, so as a result the excess energy can be used to pump protons into the intermembranous space. I hope that helps. Just remember that it's all down to redox!

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