Glycolysis
As a pathway, you don't get much more fundamental than glycolysis.Glycolysis, used to break down sugar to produce ATP, is probably used by all living cells - but what about 'unliving' cells? Yes, I am talking about the cells of the living dead, do they carry out glycolysis too?
Let's think about why glycolysis is such an important pathway...
1) The products can be used for synthesis.
2) It doesn't require mitochondria.
3) It doesn't require oxygen.
Point number three, my friends, is probably the important one. I believe that glycolysis is most likely an essential pathway for zombies, and here's why:
NO CIRCULATORY SYSTEM!!!
Zombie bodies show an amazing ability to function despite an incredible level of degradation. The other day, I saw this guy, I kid you not, stabbing a zombie with a sword - wait for it - in the heart! Any idiot knows that zombies don't need their hearts to beat! Even a decapitated zombie head will continue to move its mouth!
But this got me thinking... no blood, no pulse, no circulation. The tissue in these things must be seriously anaerobic! They have to be using glycolysis.
You could argue that the tissue is so badly decomposed that oxygen just diffuses in from the air, and I think that is quite likely, but there is a limit to how far diffusion will go. At the very least, the tissues further in, in particular, the skeletal muscle, must be using glycolysis.
'But wait', I hear you cry (quietly, so the zombies aren't alerted to your presence), 'zombies move slowly, and they never get tired. That sounds like aerobic exercise, which relies mainly on fatty acid oxidation!'
In answer to that, I would like to make three main points:
1) Fatty acid oxidation IS useless for anaerobic exercise, but glycolysis is good for everything!
2) I wasn't saying they only use glycolysis, just that it would play an important role.
3) If you can get a zombie to sign the consent form, maybe we could measure his oxygen uptake and carbon dioxide production, calculate his respiratory quotient, and settle this argument once and for all?
Obviously I am being sarcastic - I didn't claim to have all the answers - I'm just theorising! While on the run. Sheesh!
