MAKE CONNECTIONS Step 3 in Figure 9.9 is a major point of regulation of glycolysis. The enzyme phosphofructokinase is allosterically regulated by ATP and related molecules (see Concept 8.5). Considering the overall result of glycolysis, would you expect ATP to inhibit or stimulate activity of this enzyme? Explain. (Hint: Make sure you consider the role of ATP as an allosteric regulator, not as a substrate of the enzyme.)

Video transcript

Welcome back. Our next problem says during the investment phase of the glycol Asus process. The enzyme hex achiness converts glucose to And were given a diagram here with five steps. So let's look at our problem here. We know we're talking about glycol icis and we might recall from earlier concept videos that like A'Lexus consists of a total of 10 reactions divided into two phases. The first one being this investment phase and then the second five steps being the energy harvest phase. In the investment phase we have to invest energy from a T. P molecules to drive these reactions forward. In the second part we harvest the energy at the end of this process. So our diagram here is this first investment phase. Now we're looking at specifically at the step catalyzed by the enzyme xo keenness and it converts glucose. So let's look at our diagram, we see glucose right here in step one. When we look at the enzyme hex akin's a penis, we might recall from earlier videos is an enzyme that adds a phosphate group that it gets from a molecule of a T. P to another molecule. Then we have the first part of this Name, Heck. So we might recall that means six. So when we look back at our diagram, we have glucose, we have a kindness which would add a phosphate from the safety P two carbon six and that is going to generate, we can see right on the diagram glucose six phosphate. So let's look down at our answer choices and we see that choice B is indeed glucose six phosphate. So that was really straightforward. We had the answer right here on our diagram but let's just briefly look at our other choices just to confirm that and see why they aren't correct. Answer choice A says fructose, six phosphate. Um We see that right here, fructose is an ice um er of glucose. So we're not adding a phosphate. We're changing it from one to the other. And you might recall those kinds of enzymes are called Aissami races. So a kindness would not be doing that reaction. So we can eliminate a Choice C. says Fructose 1 6 by phosphate. We can see that in this step here We are adding a phosphate. 2nd phosphate to this but we're adding it to the molecule fructose. Whereas we know from our problem that we started with glucose not fructose. So let's eliminate choice c. Finally, Choice D. Says the glycerol to hide three phosphate. Well that is not even on here. That's part of that energy harvest process. So we're only looking at the investment phase D. Is not even a part of that and we can eliminate it. So our correct choices be glucose six phosphate. See you in the next video