Kreb Cycle Help

[lunamoth]

OK, so there's no getting around the fact that the ETC is composed of a series of reduction-oxidation reactions.

Each purple oval in the last diagram represents a molecule that undergoes a 'redox reaction' as the electron is passed to it, and then passed on to the next member (electron carrier) in the chain. The last electron acceptor is oxygen (O2), which is why we need oxygen to live.

Some of the electron carriers need to pick up a proton (H+) when they accept the electron. The protons are picked up from one side of the membrane when the carrier is 'reduced' and released to the other side of the membrane with it is oxidized.

So, there is a net build-up of protons on one side of the membrane (in the intermembrane space).

 

[lunamoth]

This diagram just focuses on the last step of the Electron Transport System, oxidative phosphorylation by ATP Synthase.

It's the same as the blue knob-looking thing at the end of the chain in the figure in post 19.

The protons have now been concentrated in the intermembranse space. This is a form of stored energy, like water up in a water tower that wants to flow downhill. Except the protons want to flow down the 'proton gradient.' (There is also a difference in electrical charge across the membrane, so the combined effect of proton gradient and charge difference is called the 'proton motive force.') To do this the protons have to get through the membrane, and they way they get across the membrane is by going through a channel in the ATP Synthase. Like a paddle wheel, the ATP Synthase can harness the energy released as the protons move through the channel, down the proton gradient. This captured energy is then used to phosphorylate ADP to ATP, the energy molecule.

The more NADH and FADH2 produced by the Krebs Cycle, the more protons pumped and the more ATP produced.

 

[lunamoth]

I'm sure all the figures are in your text, but I hope by putting short explanations with each you can at least start to focus on the big picture before you have to memorize all the details.

I'm sure that at the end there is also a figure like this:

So, yeah, the most famous chemical reaction in cell bio:

C6H12O6 (glucose) + 6 O2 -----> 6 CO2 + 6 H2O + 36 ATP (energy)

 

[Ringer]

I hope you're one smart 4 year old!

 

[painted wolf]

Here is a little animation of the Krebs cycle
krebstca

Here is a self testing application
Citric Acid Cycle - Self Quiz

I'll see what else I can find.

wa:do