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Seriously. Stick with me here; glycolysis is cool.
In a ten-step process, our cells break up a glucose -- one of the simplest sugars, a six-carbon ring -- into two three-carbon strings ("pyruvate") to feed to our mitochondria. From this we get some energy, plus the promise of a big pile more once the mitochondria get going.
The first step of this process is to dump a phosphate group onto the glucose. This achieves three things: 1) put the molecule in a higher-energy state so the rest of the reaction will want to run downhill, 2) trap the glucose where it is because apparently phosphorylated glucose can't get through cell membranes any more, 3) suck more glucose in to the cell from the bloodstream, because hey wow, now there's a concentration gradient of glucose, because the phosphorylated stuff in here doesn't count any more, so new stuff flows in to balance the concentrations again.
I think that's elegant to begin with. All three things get done with one operation. Power up, grab the stuff you need, and make sure more stuff you need is coming. But the thing that makes my inner engineer go "yay!" is this:
Glycolysis, like many chemical processes in our cells, is inhibited by the presence of enough of its end products. Reactions don't run away forever. In this case, it's that very first step that gets inhibited. We don't phosphorylate -- and trap, and collect more of -- the sugar if we can't finish the process of using it. We don't waste the energy on it and we don't bogart the glucose fuel.
Speaking of not wasting, lactate is just as cool. Our bodies have thought of stuff, man. They've got it handled.
(But I still want a word with the designer on the subject of knees.)
In a ten-step process, our cells break up a glucose -- one of the simplest sugars, a six-carbon ring -- into two three-carbon strings ("pyruvate") to feed to our mitochondria. From this we get some energy, plus the promise of a big pile more once the mitochondria get going.
The first step of this process is to dump a phosphate group onto the glucose. This achieves three things: 1) put the molecule in a higher-energy state so the rest of the reaction will want to run downhill, 2) trap the glucose where it is because apparently phosphorylated glucose can't get through cell membranes any more, 3) suck more glucose in to the cell from the bloodstream, because hey wow, now there's a concentration gradient of glucose, because the phosphorylated stuff in here doesn't count any more, so new stuff flows in to balance the concentrations again.
I think that's elegant to begin with. All three things get done with one operation. Power up, grab the stuff you need, and make sure more stuff you need is coming. But the thing that makes my inner engineer go "yay!" is this:
Glycolysis, like many chemical processes in our cells, is inhibited by the presence of enough of its end products. Reactions don't run away forever. In this case, it's that very first step that gets inhibited. We don't phosphorylate -- and trap, and collect more of -- the sugar if we can't finish the process of using it. We don't waste the energy on it and we don't bogart the glucose fuel.
Speaking of not wasting, lactate is just as cool. Our bodies have thought of stuff, man. They've got it handled.
(But I still want a word with the designer on the subject of knees.)
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