Gluconeogenesis Evangelion.

Why does half of Biochemistry sound like Russian swearwords? Seriously, with stuff like Pyruvate, Succinate and Fumarate, one has got to wonder just what the flying Arceus were they thinking.

Also we have to remember far too many enzymes.

The Mitochondrial Matrix has you.

Poor, poor Glucose. All it wanted was to be left alone. Instead, it is subjected to a long, torturous process so intricate that it should probably be banned by the Geneva convention.

Shortly after entering the cell, it's randomly attacked by Hexokinase which shackles a Phosphate group of ATP origin to its sixth carbon - so it can't escape. From there, it either gets welded to many others of its kind to form Glycogen, which is shoved into the dark corners of the cell to be sliced later when needed, or it is beaten into submission by a Phosphohexose Isomerase enzyme which leaves it with a psychological trauma and a completely rearranged infrastructure.

The former Glucose 6-Phosphate has little time to come to terms with its new identity as Fructose-6-Phosphate before having to come to terms with not being a Fructose 6-Phosphate anymore - as it is immediately taken up by a complex with a long, toothbreaking name which shall be known as PFK1 1to save your minds. There, it has ANOTHER Phosphate group of ATP origin welded to it, this time on carbon #1, and is released as Fructose 1-6-Biphosphate. (Glucose didn't even know it was biphosphate-curious before this stage, too). As if that's not enough, it is then cruelly sliced in half by Aldolase, and its top half is rearranged to be a copy of its bottom half by Triose-Phosphate-Isomerase - which results in two molecules of Glyceraldehyde 3-Phosphate.

So, after being chained, drawn and quartered, Glyceraldehyde 3-Phosphate, merely half of its former self chained to an unsightly phosphate group, is slapped in the head with another phosphate group, this time inorganic by a Dehydrogenase enzyme - in a process which tears a hydrogen from its head while it's forced to watch some sassy NAD+ molecule use it to become NADH and run off giggling. Before it has the time to get used to being Phosphorylized TWICE, a Kinase enzyme comes along, cuts off the newly attached phosphate group and sticks it onto an ADP molecule, turning it into ATP. Without giving it its hydrogen back. Now 3-Phosphoglycerate (as if it didn't have enough of an identity crisis!), it gets taken in by an enzyme called Phosphoglycerate Mutase - which takes away the phosphate group, giving it the illusion of freedom for one sweet moment... before SLAPPING IT WITH A PHOSPHATE ON ANOTHER CARBON!

2-Phosphoglycerate is, at this point, practically crying its nonexistent eyes out - but the cell wouldn't even give it that pleasure. No, It then slaps it with the enzyme Enolate, which sucks the moisture out of it, dehydrates it, and leaves it as Phosphoenol Pyruvate - the first Russian Curseword of many in this long, horribly painful story. Pyruvate Kinase, the last enzyme in the process, rips the phosphate off and welds it to ATP, leaving our poor, miserable half glucose as Pyruvate.

Upon being released, Pyruvate attempts to find his other half, but among the other molecules of Pyruvate, it cannot find the lost part of its past existence. Sad and broken, it wanders off to find a new meaning for its life.

Sometimes, it's unlucky enough to be recycled into Glucose with some other Pyruvate molecule that would never understand it the way its other half did. Other times, it finds its death within the walls of the mighty Pyruvate Dehydrogenase Complex - which subjects it to nine levels of hell - its Carboxyl head is cut off by a Vitamin B derivative, it is hung out to dry on a sprig of Lipoic acid and has some weird side-group full of Sulfur welded to its face, from which it gets hurled into the depths of an organelle with a silly name and tossed into an eternal swirl in which The Enzyme (A Lie of Some Kind) catalyzes the reaction that turns (Chemical That Sounds Like A Russian Curseword Of Some Kind) into (Another Chemical That Sounds Like A Russian Curseword Of Some Kind), rinse and repeat.

This is the Krebs Cycle - the grindery - what churns out the ATP for the cell.

It all starts with a condensation reaction in which Pyruvate is welded, still dazed from its experiences in the Glycolysis path - to Oxaloacetate, releasing it from the sulfurous grip of Coenzyme-A but sticking a four-carbon tail on it which leaves a sour taste in its mouth. And everyone else's considering that now, it's Citrate.

At this point it realizes that life is a lemon and it wants its money back.

after being released from Citrate Synthase, the newly formed Citrate is then scrambled by Aconitase into Cis-Aconitate for a few brief moments before being scrambled again by the very same enzyme into Isocitrate - which is then has a Carboxyl group chopped off its head and gets oxidized along the way into Alpha-Ketoglutarate. Alpha-Ketoglutarate is yoinked into a massive complex which once again slices off its Carboxyl group, oxidizes it and reintroduces it to Coenzyme-A, leaving it a Succinyl-CoA - which proceeds to have CoA removed from it by a synthetase in a contrived process that somehow welds a phosphate to GDP to create GTP. It's Succinate now.

Yes these names get even worse.

Succinate gets yoinked into a complex which sucks hydrogens off of it and turns it into Fumarate (where do these hydrogens go? stay tuned!). Fumarate is attacked by another enzyme, named Fumarase, which turns it into L-Malate, which then proceeds to get oxydized into Oxaloacetate, and BACK TO THE BEGINNING OF THE CIRCLE IT GOES, FOR ALL ETERNITY.

All it wanted was to be left alone. It never asked to be the father of two molecules of ATP, 2 molecules of GTP, 10 molecules of NADH and 2 molecules of FADH2. It never asked for all this stupid oxidation to happen. And no one weeps for it. They just keep on eating it.

It can be then taken as a small bit of comfort that all these hydrogens and electrons lopped off of it undergo their own torture by passing through a series of complexes that transfer them from NADH and FADH2 to a substance known only as Q, then into Cytochrome-C, then into Oxygen, all the while sucking protons from the Mitochondrial Matrix and shoving them into the intermembranal space between the Mitochondria's external membrane and its internal membrane, that these protons are dying to get back into the Matrix, and that their only way to do so is to go into a great bloody revolving door which squeezes ADP and inorganic phosphate into each other and churns out ATP. Which means that basically it is suffering an eternal cycle of destruction and recreation for the greater good of the organism.

Unless someone shoves in some uncoupling agent like DNP or FCCP which move protons in and out of the membrane freely and thus rapes the proton gradient that the complexes mentioned above worked so hard to create.

And you think YOUR life sucks?