Krebs Cycle/TCA Cycle/Citric Acid Cycle

Krebs Cycle/TCA Cycle/Citric Acid Cycle

Takes place inside the mitochondrial matrix HOWEVER succinate dehydrogenase is bound to the membrane and so this step occurs there. It is the only enzyme that participates in both the krebs cycle and the electron transport chain.

Two molecules of carbon dioxide are given off

One molecule of ATP is formed (it’s not, it’s GTP which is considered an ATP equivalent - your examiner may or may not like this)

Three molecules of NAD+ are combined with hydrogen (NAD+ → NADH)

One molecule of FAD+ combines with hydrogen (FAD+ → FADH)

Because two acetyl-CoA molecules are produced from each glucose molecule, two cycles are required per glucose molecule. Therefore, at the end of two cycles, the products are: two ATP(GTP), six NADH2, two FADH2 and four CO2.

How to learn it!!!

Can———-Citrate

Adam———-(cis)-Aconitate

Intrigue———-Isocitrate

A———-alpha-ketoglutarate

Super———-Succinyl-CoA

Sexy———-Succinate

Foxy———-Fumarate

Mama———-Malate

Ok!———-Oxaloacetate

(i stole this mnemonic from here)

Here’s a gap-fill game for practise

note: Citrate= Citric Acid, Fumarate= Fumaric Acid, etc…

Enzymes

For MOST of the enzymes, the name of the enzyme consist of the molecules it modifies(the molecule directly before it, and the function the molecule carries out)

If you’ve learnt the above order then you can use this to apply that

So———-citrate Synthetase

At———-Aconitase

Another———-Aconitase

Dance———-isocitrate Dehydrogenase

Devon———-alpha-ketoglutarate Dehydrogenase

Sipped———-Succinyl-CoA Synthetase

Down———-Succinate Dehydrogenase

Five———-Fumarase

Drinks———-malate Dehydrogenase

3 out of the 4 dehydrogenase enzymes will remove 2H (and an electron)  from the molecule an put it onto a NAD;

remove a CO2;

and NAD –> NADH2. 

The only exception is Succinate Dehydrogenase which places 2H atoms on an FAD molecule instead of an NAD