Zombie Metabolism: Citric Acid Cycle

Sorry to have been quiet for so long, I'm sure you must have thought that I had been eaten, or perhaps that I had taken eating (others) as a full-time occupation.

Well, you'll be glad to know that I am alive and well... ish. I am also completely alone. My group has abandoned me, they think I'm obsessed with zombie metabolism and that I have completely lost the plot. Well, I'll show them! Ah-hah-hah-haha-HA!

I don't need them! I broke into the biochem labs at Imperial all by myself, and guess what? Their back-up generators have been running this whole time! Partly reliant on solar power - yay for green enthusiasts, though they are sort of brownish-green by now...

Anyway... all the lab zombies were in pretty bad shape, probably the lack of vitamin D, so it wasn't too hard to get myself up and running in one of the labs.

I used to have so much respect for those professor-types, I used to be a PhD student, but it sort of takes the shine off when they dribble from their eyes... They just don't seem to have that same, I dunno, air of authority. Much more an air of rubbish. Eau de crap, if you will.

I digress.

I caught one of the lab zombies, and measured its RER (respiratory quotient, that is, the ratio of oxygen used, vs carbon dioxide produced), and that zombie was respiring veeeeerrrrrryyyyyy sssssllllloooowwwwllllyyyyy. The O2/CO2 was about 0.9, which implies that it is probably using a mixture of carbs and fat, and probably protein too. Would this be different if it had just eaten? There are limits to what I will do in the name of science, so unless I go on a serious revenge kick, I guess we'll never know...

So, what does this have to do with the citric acid cycle? Well, in previous posts, I was debating the importance to zombies of glycolysis (anaerobic) vs fatty acid oxidation (aerobic). Now that I have confirmed that they do use a fair amount of oxygen, it seems highly likely that they will be carrying out citric acid cycle reactions.

For those biochem enthusiasts out there who, despite the daily struggle for survival, despite the lack of edible food, and the numerous walking dead that lie in wait around every corner, never sleeping, never tiring, never feeling satiated in their desire for human flesh, still find a few moments to revise basic biochemistry (metabolism is life!), it is easy to remember why the citric acid cycle is so important.

But for those who have been distracted by the zombiepocalypse, a refresher:

The citric acid cycle takes in acetyl CoA, and via addition of oxaloacetate, oxidises it gradually to carbon dioxide, in a series of reactions that produce, in a roundabout way, energy for the cell. In order to make use of this energy (most of it anyway), the products of the citric acid cycle need to feed into the electron transport chain, which relies on oxygen.

I intend to do more studies on the zombie tissue, in particular the muscle and the nervous system. So guess what is so exciting about zombie research? The tissues continue to work after they have been removed from the body!!!

How cool is that? No more cell cultures for me. (I'm dancing around the lab right now.)

And they thought I was crazy...