The enzyme urease functions in the body to catalyze the formation of ammonia and carbon dioxide from urea as shown:
Describe what effect the following changes would have on the rate of this reaction assuming a steady state has been reached:
a. adding excess urea

Question

The enzyme urease functions in the body to catalyze the formation of ammonia and carbon dioxide from urea as shown:

Chemical reaction showing urease catalyzing urea and water into ammonia and carbon dioxide.

Describe what effect the following changes would have on the rate of this reaction assuming a steady state has been reached:

a. adding excess urea

Accepted Answer

All right. Hello everyone. So this question says that lipase is an enzyme that catalyzes the formation of fats into fatty acids. And glycerol assuming the reaction has reached a steady state, describe the effect of adding excess triglycerides on the rate of the reaction catalyzed by lipase. So here on the screen, we have four different statements which will go through individually later on as well as four different answer options labeled A through D proposing which of these statements are correct. So in this particular case, right, lipase is the enzyme, right? And the substrate happens to be triglycerides or TGS for short. This is because lipase is acting on triglycerides. So triglycerides are the substrate here. Now, generally speaking, if I was to graph the activity of this enzyme of any enzyme, really lets say the X axis is the concentration of the substrate and the y axis is the activity of said enzyme. In other words, the rate of the reaction that it's catalyzing. So up to a certain point, right, as the concentration of the substrate is increasing, so too will the activity of the enzyme. But eventually this graph is going to reach a plateau. This plateau is described as the saturation of the enzyme. So the reason the graph is plateauing. The reason why there is no further increase in activity is because the enzyme is saturated. So if all available active sites are filled, then increasing the concentration of substrate isn't going to change anything because the molecules of enzyme that are present are already occupied. So with this context in mind, let me scroll up here. So we can read the first statement here. The first statement says that the reaction rate will increase, then decrease as excess triglycerides cause a competitive inhibition of the enzyme. So this first statement is not going to be true, right? This is because competitive inhibition is not caused by an excess in substrate. The main point here is that the amount of substrate that's present in solution has reached a point where all molecules of enzyme available are occupied already. That's why the reaction rate plateaus. So it's not really a question of competitive inhibition. It's just that there isn't enough molecules of the enzyme to act on the amount of triglycerides that are present. So statement one is not true statement two, on the other hand says that the reaction rate will remain constant once all active sites are saturated with triglycerides, regardless of further increases in substrate concentration. This is true, right? Because as we were talking about earlier, trying to understand the graph that I was drawing unless you're adding more enzymes to the solution, increasing the concentration of triglycerides isn't going to change the fact that the enzyme is saturated or all molecules of the enzyme are saturated. Moving on from that statement three says that the reaction rate will decrease as excess triglycerides may inhibit the enzymes activity. This is not correct, right, because an excess in triglycerides isn't going to inhibit lipase rather, it's going to lead to the saturation of the enzyme itself. So the rate won't decrease, but it won't increase much either last but not least though we have statement number four, which reads that the reaction rate will increase to a maximum level and then plateau as the enzyme becomes saturated with triglycerides. This is correct, right? Because up until all molecules of the enzyme are occupied with triglycerides, the activity of the enzyme will increase as you increase the concentration of the substrate. So going back to our answer choices now to kind of tie everything together of the four statements provided only statements two and four were correct, which means that option B is our correct answer and there you have it. So with that being said, thank you so very much for watching. And I hope you found this helpful.

The enzyme urease functions in the body to catalyze the formation of ammonia and carbon dioxide from urea as shown:

Describe what effect the following changes would have on the rate of this reaction assuming a steady state has been reached:
a. adding excess urea

Verified video answer for a similar problem:

Key Concepts

Enzyme Catalysis

Substrate Concentration

Steady State Kinetics