Learning the Krebs Cycle: Step One

How in the world are you supposed to memorize the steps of the Krebs Cycle?

There are just eight steps, but many nearly all of these are reactions with two or more reactants and two or more products. It adds up fast.
For the exam, you are responsible for knowing six of the eight steps. Maybe you might as well just learn the whole thing.

I don't recall how I memorized the Krebs cycle, back in college.
As I try to learn it again, I am coming up with some tricks to break up the information into bite-size chunks, and spice them with tasty significance.



There are really two tasks here. We can do them one at a time.

The first task is to learn the names of the reactants, and where they go in the pathway.

The second task is to learn which of these reactions HARVEST ENERGY
(by reduction of NAD+ to NADH, or reduction of FAD to FADH2, or production of ATP) ...

…and/or RELEASE WASTE
(by splitting off a molecule of carbon dioxide).



The first task is relatively straightforward. Stare at the Krebs cycle diagram and utter the names of the metabolites, in order of appearance. Start with Citrate.

Citrate, Isocitrate, Alpha-Ketoglutarate, Succinyl-CoA, Succinate, Fumarate, Malate, Oxaloacetate.

Do it again, until these words are familiar to you.

Now make up a mnemonic to remind you of the order. I like to make up a sentence consisting of words that begin with the first letter (or better, the first two or three letters) of the corresponding word series.

Cities, isolated, actually suck successfully, fuming malodorous oxaloacetate.

You may be able to do better. (A dictionary helps.) Once you have a mnemonic you like, recite it till memorized. Then you can practice reciting the real thing.

I'll add a note on pronunciation. (You learn better if you can read out loud.)
Citrate, Iso-citrate, Alpha-Keto-glutarate, Succinyl-CoA, Succinate, Fumarate, Malate, Oxalo-acetate.


Later (posting this evening, I hope) I'll show you how I've tackled the second task. I've figured out a couple tricks for graphically conceptualizing the reaction cycle and remembering how and where you get energy harvest and waste production.

cheers,
Morgan G.