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Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway


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as we move through the Glick allergic reactions The things that I want you to pay attention. Thio are the name of the enzyme at each step, which is gonna be the first thing you see the delta g of that reaction, which is gonna tell you whether or not this is a readily reversible reaction. And the more negative the reaction theme, the deal less able to be reversed it is, or Thio put it in a less confusing way. If you have a Delta G that's close to zero, you have a readily reversible reaction. But the reactions, you have a very negative value. Those are going to be what I'm gonna call commitment steps because we're going to expend energy and commit to the pathway. So you also lastly, you gonna pay attention to your reactant or substrates, I should say, your substrates and your products. So looking here, uh, the first step of Glen Collis iss is performed by Hex, a communist. That's our enzyme. We have a pretty negative value for Delta G, meaning this is not gonna be readily reversible. That's why we have a one way arrow here and we're gonna take glucose or hex or kindness is gonna take glucose, I should say, And it's going to turn it into glucose six phosphate. It's gonna add a phosphate group onto glucose. And this actually happens as soon as glucose enters the cell. As soon as glucose enters the cell, hex ickiness performs this regardless of whether or not glucose is actually going Thio be broken down through black colossus. But if it is broken down through black Allah, assists while this is still going to be the first thing that happens to it and you can see that we have to expend an ATP Andi, that 80 p expenditure is going to allow us to attach that phosphate group under glucose. And we're going thio end up with a D. P and a proton because we are breaking that phosphate, um, that phosphate bond in ATP and that gives off proton and is going to leave a deep behind. All right, moving on to the second reaction the GLA clinic pathway. We have Basta, Hyksos, isom race and you can see here that the delta G of this reaction is pretty close to zero. And that's why we have these, um, both ways arrows, right? This means it's readily reversible reaction. And that makes sense. Because this is nice summaries, right? We're not really doing a whole lot here. We're just rearranging the molecules little bit. We're taking glucose six phosphate, and we're turning it into fructose six phosphate. And you can see, basically, we're just changing the ring structure a little bit so that carbon one is no longer part of the ring. Now the ring starts with carbon too, right? We've moved from a, uh, a six member drink to a five member dring. Now, step number three carried out by phosphate fuck geekiness. That's an enzyme name that you want to remember because it's gonna come up, Uh, many, many times, even beyond this course, probably. And foster for kindness. You can see has a pretty negative Delta G. And we have a one way arrow here, right? This is gonna be our second commitment step. And we have to burn another ATP or expend another ATP. And we're gonna do that. And we're going to foster for late fructose six phosphate. So we're gonna take fructose six phosphate from previous reaction, and we're gonna add another phosphate group onto it. You can see, right? They're making it a biss phosphate to phosphates. So this is our second commitment Step? This is going to be the last step of, um, directly investing energy. But we're not quite at the energy payoff phase yet. So remember, in terms of looking at Glen Collis Issa's, the whole we expend to 80 p per glucose. So this is the 2nd 80 p we're expending no fourth step of the reaction is performed by Al Delays. Let me just hop out of the image here so you can see the whole thing. So notice notice. Hear Al glace has a pretty high delta G. Right? So this is probably making you wonder how this reaction occurs. It all. We'll notice that this is the Delta G prime. Not there, Right? Meaning this is Delta G at, you know, standard biochemical, uh, conditions, but actually in in the cell at cellular conditions, the delta G of this reaction is actually somewhere between negative six and zero. That's why this is this is actually going to be a readily reversible reaction. So don't be fooled by this Delta G of 23.8, because it's cellular conditions. This is actually going to be more like negative six or zero and what we're gonna be doing, we're gonna be taking that fructose 16 bits phosphate. I've abbreviated it there to fit it all in one line. Great. So that's this molecule right here, and we're going to actually, um, we're going Thio split it up. Right. All Dallas, we're going to break up that alcohol, and we're going to break it up into two molecules, one of which is glycerol to hide three phosphate, which I'm going to abbreviate G three p. You may have seen this molecule before. Some other. It's sometimes called P gal, which stands for phosphate blister. Aldo hide. Um, I personally prefer G three p glycerol died three phosphate, um or rather prefer G three p is my abbreviation because I think it's closer to the name glycerol High three phosphate than P gal. It doesn't really matter. We're gonna call it G three p and a story. Now, the other molecule that it gets broken up at into is di hydroxy acetone phosphate or D H a P. So here we have G three p and this is D H. A P now G three p is ready. Thio basically continue on in Glen Collis is that's going to be the substrate of the next step. D. J P can't just jump into the next step. The D. H AP actually has to be converted into G three p, which I'm sure you can tell by looking at the structure not going to be the hardest chemical reaction to pull off as they're fairly similar. Similar molecules. So let's turn the page and take a look at what happens to D H. A P.