My advanced biochem class is interesting. It's like any other biochem class I've ever taken, with all the fun of memorizing metabolic pathways, except with the need to know the reaction mechanisms thrown in (curse you, Silverman!).
But one of the portions there started me thinking. Yes, yes, a rare event, I know.
When you exercise, your body needs to get energy quickly, and it can't wait for the normal breakdown of sugars and whatnot to get it. So, your body uses lactate dehydrogenase, an enzyme, to break down some of the normal metabolites to get fast energy. The reaction takes place partly due to the shortage of oxygen during exercise.
In yeast, a similar reaction takes place in the absence of oxygen, except the same metabolite is transformed into ethanol by a similar enzyme, alcohol dehydrogenase. It's how brewer's yeast works to make beer.
We actually have alcohol dehydrogenase in our livers. It's why our livers can change alcohol back into usable molecules.
But I was thinking to myself . . . what if, instead of lactate dehydrogenase, our muscle cells had alcohol dehydrogenase?
My first thought was that exercise would cause the body to produce ethanol. Consequently, exercise would make you intoxicated. I suppose this would instantly cure the obesity epidemic in the US. Especially at colleges. "Hey, what are you doing tonight?" "Oh, everyone's going for a jog around the frat house. I heard they're going to have stationary bikes, and even a couple of treadmills. It's gonna be awesome!"
After thinking about it for a while, though, I realize that that would never happen. In truth, you could probably never get drunk if this were the case. Maybe for a while after you exercised, while your body was breaking the alcohol back down. But the reason we get drunk is because our liver can't break down the ethanol faster than it interacts with our brain. On the other hand, if you had alcohol dehydrogenase in all of your muscle cells, the ethanol from drinking would be broken down so fast that you'd probably have to drink everclear like it was water to even feel anything, much less get drunk.
So, if any of you were hoping for better living through genetic engineering, I guess I just inflated and then burst your bubble in one fell swoop. Better luck next time.