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7. Energy and Metabolism

Enzyme Activation Energy

7. Energy and Metabolism

Enzyme Activation Energy

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concept

Enzyme Activation Energy

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in this video, we're going to begin our lesson on the enzyme activation energy. And so the activation energy is sometimes called the energy of activation, and it's commonly abbreviated as just e. A. And so the activation energy or energy of activation, or E A is really defined as the difference and energy between the reactant of a reaction and the transition state of a reaction now will define the transition state here very, very shortly. But first, focusing in on the activation energy or the E A, the EA or the activation energy represents the minimum amount of energy that's required to start a chemical reaction. Now all reactions have an activation energy, and that includes both X organic and undergone IQ reactions. And so the higher the energy of activation is, the slower the reaction will be. And so the energy of activation is really just going to dictate the speed that the reaction will occur. The higher the reaction energy of activation is, the slower the reaction will take place. And so the lower the energy of activation is, the faster the reaction will take place. Now, the transition state is defined as a temporary state of maximum energy within a reaction. And so let's take a look at our image down below to start to clear some of this stuff up. And so notice that we're showing you this graph down below where on the Y axis we have the free energy and on the X axis we have the reaction progress or the time as the reaction proceeds. And so notice that we're starting off with some reactant. And the reactant is have higher free energy than the products which are down below, which have lower free energy. And so that makes this an ex organic reaction. And so we can label. The reactant is having higher energy than the products which have low energy. And so notice that the transition state again is going to be a temporary state of maximum energy in a reaction. And so where there is maximum energy is at the peak of this curve here, and so at the very, very peak is where we will find the transition state and so weaken label this as the transition state. And so the activation energy recall is defined as the difference in energy between the reactant and the transition state. And so if we find the reacting to notice, the reactant are right here, and the transition state is right here. And so the difference in energy between the two is gonna be represented by this region. That is right here, the activation energy. And so we can label the activation energy, which is shown by this yellow bar here. The activation energy is abbreviated as E. A. And it's going to represent the minimum amount of energy required to start the chemical reaction. And so, even in an X organic reaction like this, there is a minimum amount of energy that needs to be overcome in order for the reaction to proceed. And so this here, eyes showing how the activation energy is represented by this difference in energy between the transition state and the reactant and the activation energy is going to determine the speed of the reaction. The higher the activation energy is, the slower the reaction will be. And so now that we better we under we've introduced the activation energy or e A. And our next video, we'll talk about how enzymes affect the activation energy. So I'll see you all in that video

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concept

Enzymes Lower Activation Energy

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So now that we've introduced the activation energy in our last lesson video in this video, we're going to talk about how enzymes affect the activation energy of chemical reactions and, more specifically, how enzymes will lower the activation energy. And so, once again, enzymes catalyze chemical reactions by lowering their activation energy barrier or essentially lowering the transition state energy. Now reactions are going to occur much, much faster in the presence of an enzyme because the activation energy has been lowered. And remember the lower the activation energy. The faster the reaction, the higher the activation energy, the slower the reaction. And so let's take a look at our example down below to clear some of this up, looking at the reaction coordinate for enzymatic catalysis. And so, once again, we've got this graph where we got the free energy on the Y axis and the reaction progress on the X axis or the time as the reaction progresses. And so notice that we're showing an ex organic reaction because the reactions have higher energy than the products which have lower energy. And so notice that the activation energy eyes being represented in two different ways here in this image, and that's because we have two different curves. We have this blue curve that you can see right here and then we also have this red curve that you can see right here. And so the blue curve corresponds with the enzymatic reaction without an enzyme, and so you can see that the energy of activation without the enzyme is quite large. You can see that it's gonna be the difference in the energy between the reactant and the transition state for the blue curve, which is this large blue era that you see right here. This is again without an enzyme, so notice that the activation energy is large and that makes the reaction slow. But then notice that with the red curve right here, this represents the same exact chemical reaction except in the presence of an enzyme with an enzyme being present. And so notice that the red curve here has a much smaller activation energy. You can see it's shorter in comparison to the activation energy without an enzyme, and so because the activation energy is smaller, with an enzyme that makes the reaction occur much, much faster, and so you can see that the transition state here. For, uh, the reaction in the presence of an enzyme with an enzyme is much, much lower, and so that makes the activation energy lower. And that ends up making the reaction proceed faster in the presence of an enzyme. So, really, the main take away here of this video is that enzyme speed up chemical reactions by lowering the energy of activation. And so this here concludes our video, and we'll be able to get some practice applying these concepts as we move forward in our course, so I'll see you all in our next video.

3

Problem

Problem

Which of the following statements is TRUE regarding an enzyme's function?
a) It is generally increased if the structure or conformation of an enzyme is altered.
b) It is independent of factors such as pH and temperature.
c) It increases the rate of chemical reactions by lowering activation energy barriers.

A

It is generally increased if the structure or conformation of an enzyme is altered.

B

It is independent of factors such as pH and temperature.

C

It increases the rate of chemical reactions by lowering activation energy barriers.

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PRACTICE PROBLEMS AND ACTIVITIES (7)