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So this is the side of the mother. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
This is the side of the fetus. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
So what happens is carbon dioxide moves down its concentration gradient from this side from the fetus's side to the mother's side. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
Now, as it moves this way, what happens is the concentration of the carbon, the oxide, begins to increase within the side of the mother. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
And by increasing the CO2 concentration, that makes the hemoglobin much more likely to actually release the oxygen. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
And once oxygen is released, we have the bore effect. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
So that is the bore effect. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
So as a result of the release of carbon dioxide onto the mother's side we have the bore effect take place on the mother's side. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
The carbon dioxide affects the affinity of hemoglobin, decreases its affinity for hemoglobin, decreases hemoglobin's affinity for oxygen. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
Oxygen is released, and then it moves into the side of our fetus. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
Now, at the same time that carbon dioxide concentration on the mother's side is increasing the carbon dioxide on the fetus side is decreasing in concentration because this is moving this way. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
Now, when we decrease the concentration of carbon dioxide that means less of the CO2 can actually affect that hemoglobin on the side of the fetus. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
And so we also see a bore effect taking place on this side. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
So less CO2 means more of that hemoglobin will be able to buy to more of that oxygen that is coming in. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
And so this is the double bore effect that takes place not only on the mother's side but also on the side of the fetus. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
So these three factors actually facilitate the exchange of gases inside our placenta. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
So we have the the ability of that fetal hemoglobin to actually bind to oxygen much more readily than the adult hemoglobin. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
That is factor number one. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
Factor number two is the fact that inside the mother we have a higher amount of oxygen than inside the fetus. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
And so it moves down its concentration and pressure gradient from the mother's side to the fetus side. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
And finally, we also have the double bore effect. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
So the fact that carbon dioxide is being pumped is being expelled into the blood of that mother causes the hemoglobin inside this mother's area to basically decrease its affinity for oxygen. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
And because of that, more oxygen is expelled, is released, and then the oxygen moves into the capillaries of the Corianic villi. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
And as the concentration of carbon dioxide decreases within the capillaries of that fetus we have less CO2 that can affect hemoglobin's ability to bind to oxygen. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
And so because we have less CO2 we have more of that fetal hemoglobin that will be able to bind to oxygen. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
And this is called the double bore effect. | Gas Exchange in Placenta, Fetal Hemoglobin and Double Bohr Effect .txt |
In the cells of our body. | Effect of Enzymes on Rate Law and Rate Constant .txt |
We have many different types of biological processes that are catalyzed by enzymes. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And what these enzymes do is they speed up the rates of these biological reactions. | Effect of Enzymes on Rate Law and Rate Constant .txt |
Now, because enzymes affect the rates, to actually understand how enzymes work, we have to understand the rates of these enzymecatalyzed reactions. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And in fact, enzyme kinetics is the study of the rates of these enzyme catalyzed reactions that take place inside our body. | Effect of Enzymes on Rate Law and Rate Constant .txt |
Now, in the next lecture we're going to begin our study of enzyme kinetics. | Effect of Enzymes on Rate Law and Rate Constant .txt |
But in this lecture we're going to remember some basic information about how to actually represent and express the rates of chemical reactions. | Effect of Enzymes on Rate Law and Rate Constant .txt |
We're going to remember what the rate law is and what the rate constant is and how enzymes affect these two quantities. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And we're also going to remember what the order of reaction is. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So let's begin with the following hypothetical chemical reaction. | Effect of Enzymes on Rate Law and Rate Constant .txt |
We have reactants A and B that are being consumed and C and D, the products are being formed. | Effect of Enzymes on Rate Law and Rate Constant .txt |
Now because we have a one to one to one to 1 mol ratio, because the coefficients are one to one to one to one and because these are being consumed and these are being produced at the same time these are being consumed. | Effect of Enzymes on Rate Law and Rate Constant .txt |
These four equations basically describe the rates of these individual reactants. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So as the reaction is progressing from the reactant side to the product side, a is being consumed. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And that's why the rate of A is negative and the rate of A is simply given by the change in the concentration of A with respect to some time interval and likewise B is also being consumed. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So the rate of B is negative and it's given by delta the change in concentration of B with respect to the time and likewise over the same time interval. | Effect of Enzymes on Rate Law and Rate Constant .txt |
These are the rates of C and D. So the rate of C is the change in C with respect to T and the rate of D is change in D with respect to T. Now, these equations aren't very useful. | Effect of Enzymes on Rate Law and Rate Constant .txt |
What we actually want to be able to express is the entire rate of that entire equation as a whole. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And this is where the rate law and the rate constant comes into play. | Effect of Enzymes on Rate Law and Rate Constant .txt |
The rate law basically uses the rate constant as well as the concentrations of reactants to basically express mathematically what the rate of that chemical reaction is as a whole. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So let's suppose we have the following elementary reaction. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So what do we mean by an elementary reaction? | Effect of Enzymes on Rate Law and Rate Constant .txt |
Well, recall from general chemistry, an elementary reaction is a reaction that takes place in a single step. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And the important thing about elementary reactions that you have to remember is in any elementary reaction we can use the coefficient of that reactant to basically determine what the order of that reactant is within that rate law. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So we can use the coefficient in front of the reactant to basically tell us what the exponent value is of that particular reactant in that rate law. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So the rate law of the above elementary chemical reaction is usually described by using the rate law and the rate will depends on the rate constant k and usually depends on the concentration of the reactants. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So in this lecture we're only going to look at elementary reactions. | Effect of Enzymes on Rate Law and Rate Constant .txt |
But you have to remember that if we're dealing with a multistep complicated reaction, then we cannot simply use the coefficients. | Effect of Enzymes on Rate Law and Rate Constant .txt |
In that case, we have to determine the rate law experimentally. | Effect of Enzymes on Rate Law and Rate Constant .txt |
But if we have a single step reaction, then we can use the coefficients to calculate the rate law. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So in this particular case, going from A to B, a is the reactant and B is the product. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And let's suppose the rate constant is k one and that means the rate law for this reaction is given by so the rate of the four reaction v forward is equal to k one multiplied by the concentration of A to the power of one, because the coefficient here is one. | Effect of Enzymes on Rate Law and Rate Constant .txt |
If this coefficient was two, then this exponent here would be two and so forth. | Effect of Enzymes on Rate Law and Rate Constant .txt |
Now, if we go in reverse, then the only thing that changes is this becomes the reactor, this becomes the product. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And so we replace the concentration A with concentration B and we replace k one with K minus one. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And remember that if this reaction achieves equilibrium, then the rate of the forward will be equal to the rate of the reverse and these two quantities will be equal. | Effect of Enzymes on Rate Law and Rate Constant .txt |
Now notice, k one is not necessarily equal to K minus one. | Effect of Enzymes on Rate Law and Rate Constant .txt |
K one is only equal to K minus one if the concentration of A is equal to the concentration of b when equilibrium is actually achieved. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So normally k one is not the same as k minus one. | Effect of Enzymes on Rate Law and Rate Constant .txt |
Now, what exactly is the meaning of k? | Effect of Enzymes on Rate Law and Rate Constant .txt |
What exactly is the meaning of the rate constant? | Effect of Enzymes on Rate Law and Rate Constant .txt |
Well, the rate constant is given by the following equation known as the radius equation. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And this Iranius equation describes what the rate constant actually symbolizes. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So the rate constant K is equal to the product of the frequency factor a and e to the power of negative EA divided by RT where r is the gas constant, t is the absolute temperature, EA is our activation energy. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So right away, because the activation energy appears in this arrangeous equation, that means changing the activation energy changes the value of K. And so when an enzyme acts on a chemical reaction, it affects the k value. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And that makes sense because we know that enzymes do not affect the concentrations of reactants or products. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And so if enzymes increase the rate of the reaction and they cannot increase the a value or b, that means they have to increase the k value, the rate constant. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So if we look at the radius equation, we see that if we decrease the value of EA. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So remember enzymes, they stabilize the energy of the transition state, decreasing the energy of the transition state and that decreases the free energy of activation. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And so when enzymes decrease the activation energy, EA, they essentially decrease this entire exponent. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And since the exponent is negative, what that means is this entire quantity will increase. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And so by decreasing the activation energy our enzyme increases the rate constant and that's precisely what increases the rate of that reaction. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So remember, inside our body the temperature remains constant. | Effect of Enzymes on Rate Law and Rate Constant .txt |
The core temperature is about 37 degrees Celsius. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And that means all the reactions taking place inside our body take place at a constant temperature. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So the temperature remains constant. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And what that means is the enzymes have to affect the EA to actually change the K to increase the rate of that particular reaction. | Effect of Enzymes on Rate Law and Rate Constant .txt |
Now? | Effect of Enzymes on Rate Law and Rate Constant .txt |
What about a Well, A is known as the frequency factor and this basically describes the frequency of collision between the reactants. | Effect of Enzymes on Rate Law and Rate Constant .txt |
Remember, according to the collision theory, for a reaction to actually take place those reactants have to collide with a great enough energy. | Effect of Enzymes on Rate Law and Rate Constant .txt |
Now this collision frequency is described by A. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And we know if the collisions are more frequent then it's more likely that we're going to produce the products. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And so if the frequency of collision increases, the A value increases and the K will also increase. | Effect of Enzymes on Rate Law and Rate Constant .txt |
Now, does the enzyme affect A? | Effect of Enzymes on Rate Law and Rate Constant .txt |
Well, remember, the enzyme places the substrate inside the active side and what that does is it creates a microenvironment and it basically decreases the space in which the reactants are colliding. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And if the space is smaller, the collision between the reactants will be much more likely. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And so enzymes can also actually increase A because they decrease the space in which the reactants are actually allowed to move. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And so if the reactants basically collide more, the A value increases. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So we see that enzymes predominantly affect the EA, but they can also affect A, they can decrease EA and increase A. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And in both cases we basically increase the value of K. So enzymes affect the rate constant, they increase the rate constant. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And so that in turn increases the rate of that reaction inside the rate law. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So enzymes affect the rate constant and in turn affect the rate law. | Effect of Enzymes on Rate Law and Rate Constant .txt |
So if we take a look at the following elementary reaction in which we take A and produce B, where K is the rate constant, we see that this is our rate law. | Effect of Enzymes on Rate Law and Rate Constant .txt |
And when an enzyme is added into the mixture, the enzyme will increase K. It will not affect the concentration of A. | Effect of Enzymes on Rate Law and Rate Constant .txt |
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