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And because of their lighter nature they're going to be less dense and so they're going to appear farther to the left along that x axis. Now, what do they see after a second cycle of division? So following a second division, a second replication, once we extract the DNA molecules from those cells, this is what we saw. Now we saw two individual bands and noticed that these two bands are separated. What that means is one band describes a lighter DNA molecule and the other one describes a heavier DNA molecule. Also notice that this second band is along the same, I guess, y direction, y axis as this band here. | Meselson and Stahl Experiment .txt |
Now we saw two individual bands and noticed that these two bands are separated. What that means is one band describes a lighter DNA molecule and the other one describes a heavier DNA molecule. Also notice that this second band is along the same, I guess, y direction, y axis as this band here. And that means these two bands here have the same exact heaviness have the same exact density while this band, the second band, is found farther to the left along the x axis and so it is slightly lighter. Now, what exactly does that actually describe? Well, once again, it confirms the semiconservative replication process. | Meselson and Stahl Experiment .txt |
And that means these two bands here have the same exact heaviness have the same exact density while this band, the second band, is found farther to the left along the x axis and so it is slightly lighter. Now, what exactly does that actually describe? Well, once again, it confirms the semiconservative replication process. What that means is each one of these strands here separated. Now, when the N 15 strand is separated, the purple one, we use the N 14 isotopes. And so we basically form this molecule right over here. | Meselson and Stahl Experiment .txt |
What that means is each one of these strands here separated. Now, when the N 15 strand is separated, the purple one, we use the N 14 isotopes. And so we basically form this molecule right over here. And likewise, when these two separate and when we use this purple N 15 band, what happens is we essentially form this molecule here. But when these two separate and instead we use the brown strand here and the brown strand here because we have the N 14 in our mixture and the N 14 will be used to synthesize that. Dodostran these are the DNA molecules that we're going to form and they're going to consist purely of these N 14 atoms. | Meselson and Stahl Experiment .txt |
And likewise, when these two separate and when we use this purple N 15 band, what happens is we essentially form this molecule here. But when these two separate and instead we use the brown strand here and the brown strand here because we have the N 14 in our mixture and the N 14 will be used to synthesize that. Dodostran these are the DNA molecules that we're going to form and they're going to consist purely of these N 14 atoms. And because N 14 is lighter and less dense than the N 15 this will be this band right here. So this is purely N 14 while this band here is the N 14 N 15 because it consists of a combination. And likewise this band describes the N 14 and 15 DNA molecule in which half of it is that original parent strand and the other half is that newly synthesized N 14 lida strand. | Meselson and Stahl Experiment .txt |
And what that means is there's a very important step that is missing in glycolysis. And actually, because this step is missing, glycolysis all by itself will not be able to continue for a very long time. So what step is missing from glycolysis? Well, let's run that. Remember step six of glycolysis. So what happened in step six? | Ethanol and Lactic Acid Fermentation .txt |
Well, let's run that. Remember step six of glycolysis. So what happened in step six? Well, in step six of glycolys, that's the beginning of stage three. We essentially take a molecule we call gap. So glyceroaldehyde three phosphate and we oxidize it into a molecule we call 13 BPG one three bisphosphoglyceride. | Ethanol and Lactic Acid Fermentation .txt |
Well, in step six of glycolys, that's the beginning of stage three. We essentially take a molecule we call gap. So glyceroaldehyde three phosphate and we oxidize it into a molecule we call 13 BPG one three bisphosphoglyceride. And the enzyme that catalyzes this reaction is known as gap dehydrogenase. Now, for gap dehydrogenase to actually function, it must be able to use a coenzyme we call nicotine amide adenine Dinucleotide in its oxidized form, namely NAD plus. And if it can't use NAD plus, if for some reason the NAD plus is not available in a cell, this process will essentially stop. | Ethanol and Lactic Acid Fermentation .txt |
And the enzyme that catalyzes this reaction is known as gap dehydrogenase. Now, for gap dehydrogenase to actually function, it must be able to use a coenzyme we call nicotine amide adenine Dinucleotide in its oxidized form, namely NAD plus. And if it can't use NAD plus, if for some reason the NAD plus is not available in a cell, this process will essentially stop. An entire process of glycolysis will come to stop. Now, the problem with step six and the remaining steps of glycolysis is once the cell uses up NAD plus and transforms it into NADH, that NAD plus is not actually regenerated. So in the process of glycolysis, we use up NAD plus molecules to form the nadhs. | Ethanol and Lactic Acid Fermentation .txt |
An entire process of glycolysis will come to stop. Now, the problem with step six and the remaining steps of glycolysis is once the cell uses up NAD plus and transforms it into NADH, that NAD plus is not actually regenerated. So in the process of glycolysis, we use up NAD plus molecules to form the nadhs. And those NAD pluses are not actually regenerated at the end of glycolysis. And because our cells have a limited supply of the NAD plus molecules, and by the way, the NAD plus molecules actually are derivatives of niacin, which is vitamin B three. And so because our cells have a limited supply of the NAD plus, this process of glycolysis will eventually come to a stop when that cell runs out of that limited supply of nicotine amyde adenine Dinucleotide. | Ethanol and Lactic Acid Fermentation .txt |
And those NAD pluses are not actually regenerated at the end of glycolysis. And because our cells have a limited supply of the NAD plus molecules, and by the way, the NAD plus molecules actually are derivatives of niacin, which is vitamin B three. And so because our cells have a limited supply of the NAD plus, this process of glycolysis will eventually come to a stop when that cell runs out of that limited supply of nicotine amyde adenine Dinucleotide. And so for this not to actually take place, something else must be done after glycolysis takes place. So something must be done to regenerate that coenzyme the NAD plus that is necessary for the activity of gap dehydrogenase that basically catalyzes step six of glycolysis. So once again, in step six of glycolysis, NAD plus nicotine amide adenine dinucleotide in the oxidized form, this is the molecule that comes from niacin, vitamin B three. | Ethanol and Lactic Acid Fermentation .txt |
And so for this not to actually take place, something else must be done after glycolysis takes place. So something must be done to regenerate that coenzyme the NAD plus that is necessary for the activity of gap dehydrogenase that basically catalyzes step six of glycolysis. So once again, in step six of glycolysis, NAD plus nicotine amide adenine dinucleotide in the oxidized form, this is the molecule that comes from niacin, vitamin B three. Basically, this molecule acts as a coenzyme and helps gap dehydrogenates to transform the gap molecule glyceroaldehyde three phosphate into one three bisphospho bisphosphoglycerate. And in this process, we see that NAD plus was used up and it was never actually regenerated in the remaining steps of glycolysis. And so this means that glycolysis basically depends on NAD plus. | Ethanol and Lactic Acid Fermentation .txt |
Basically, this molecule acts as a coenzyme and helps gap dehydrogenates to transform the gap molecule glyceroaldehyde three phosphate into one three bisphospho bisphosphoglycerate. And in this process, we see that NAD plus was used up and it was never actually regenerated in the remaining steps of glycolysis. And so this means that glycolysis basically depends on NAD plus. And when the concentration of NAD plus basically runs out, the process of glycolysis will come to a stop and the cell will no longer be able to actually produce those ATP molecules. And the way that our cells fix the problem is by taking the Peruvate molecule and actually using that Peruvate molecule, metabolizing it to regenerate those NAD plus molecules so in order for Glycolysis to proceed over and over and over, the NAD plus must be regenerated. And so the cell regenerates the NAD plus by breaking down, metabolizing those pyruvate molecules produced at the end of Glycolysis. | Ethanol and Lactic Acid Fermentation .txt |
And when the concentration of NAD plus basically runs out, the process of glycolysis will come to a stop and the cell will no longer be able to actually produce those ATP molecules. And the way that our cells fix the problem is by taking the Peruvate molecule and actually using that Peruvate molecule, metabolizing it to regenerate those NAD plus molecules so in order for Glycolysis to proceed over and over and over, the NAD plus must be regenerated. And so the cell regenerates the NAD plus by breaking down, metabolizing those pyruvate molecules produced at the end of Glycolysis. Now, there are two major pathways. We have an aerobic pathway and an anaerobic pathway. Now, in aerobic, that simply means we're going to use oxygen. | Ethanol and Lactic Acid Fermentation .txt |
Now, there are two major pathways. We have an aerobic pathway and an anaerobic pathway. Now, in aerobic, that simply means we're going to use oxygen. And in this particular case, the pyruvate molecules travel into the mitochondria and there they're broken down into acetylcoenzyme A. And that molecule goes into the citric acid cycle and that uses the electron transport chain to basically regenerate those NAD plus molecules. But we'll focus on that process in a future lecture. | Ethanol and Lactic Acid Fermentation .txt |
And in this particular case, the pyruvate molecules travel into the mitochondria and there they're broken down into acetylcoenzyme A. And that molecule goes into the citric acid cycle and that uses the electron transport chain to basically regenerate those NAD plus molecules. But we'll focus on that process in a future lecture. In this lecture, I'd like to focus on the anaerobic process. The anaerobic process takes place in the absence of oxygen. And our own cells and many other cells in nature use this specific type of process that we call fermentation. | Ethanol and Lactic Acid Fermentation .txt |
In this lecture, I'd like to focus on the anaerobic process. The anaerobic process takes place in the absence of oxygen. And our own cells and many other cells in nature use this specific type of process that we call fermentation. Now, there are many different examples of fermentation processes. But the most common fermentation processes are those that produce lactate or ethanol from the pyruvate molecules. So these are known as ethanol fermentation or alcoholic fermentation or in the case of producing lactate which is actually the conjugate base of lactic acid. | Ethanol and Lactic Acid Fermentation .txt |
Now, there are many different examples of fermentation processes. But the most common fermentation processes are those that produce lactate or ethanol from the pyruvate molecules. So these are known as ethanol fermentation or alcoholic fermentation or in the case of producing lactate which is actually the conjugate base of lactic acid. This is known as lactic acid fermentation. So let's focus on ethanol fermentation. So basically, yeast cells and several other bacterial cells utilize this process of fermentation. | Ethanol and Lactic Acid Fermentation .txt |
This is known as lactic acid fermentation. So let's focus on ethanol fermentation. So basically, yeast cells and several other bacterial cells utilize this process of fermentation. So alcoholic fermentation to basically reform those NAD plus coenzyme molecules. And what happens is the pyruvate molecules ultimately are transformed into the ethanol molecule of this process actually takes place in two steps. The first step is a decarboxylation process and the enzyme that catalyzes this process is known as pyruvate decarboxylase. | Ethanol and Lactic Acid Fermentation .txt |
So alcoholic fermentation to basically reform those NAD plus coenzyme molecules. And what happens is the pyruvate molecules ultimately are transformed into the ethanol molecule of this process actually takes place in two steps. The first step is a decarboxylation process and the enzyme that catalyzes this process is known as pyruvate decarboxylase. And so we begin with our pyruvate molecule and in the presence of an H plus ion as well as an important coenzyme known as thymine pyrophosphate, which actually is a thymine vitamin derivative. So thiamine is vitamin B one. So in the presence of this coenzyme, what will happen is this bond will be broken. | Ethanol and Lactic Acid Fermentation .txt |
And so we begin with our pyruvate molecule and in the presence of an H plus ion as well as an important coenzyme known as thymine pyrophosphate, which actually is a thymine vitamin derivative. So thiamine is vitamin B one. So in the presence of this coenzyme, what will happen is this bond will be broken. This H plus will basically create a bond here while this carbon dioxide molecule shown in blue will be released into the environment in the gas form. So we have this CO2 molecule in the gas form and we have this molecule basically this entire structure plus this H. And this is known as acetyl aldehyde. Now, this is the first step. | Ethanol and Lactic Acid Fermentation .txt |
This H plus will basically create a bond here while this carbon dioxide molecule shown in blue will be released into the environment in the gas form. So we have this CO2 molecule in the gas form and we have this molecule basically this entire structure plus this H. And this is known as acetyl aldehyde. Now, this is the first step. And in the second step, this is when we actually produce that ethanol. So in the first step, we have the decarboxylation reaction catalyzed by pyruvate decarboxylase the coenzyme Thiamine pyrophosphate, which is a Thiamine derivative. So Thiamine vitamin is the vitamin B one. | Ethanol and Lactic Acid Fermentation .txt |
And in the second step, this is when we actually produce that ethanol. So in the first step, we have the decarboxylation reaction catalyzed by pyruvate decarboxylase the coenzyme Thiamine pyrophosphate, which is a Thiamine derivative. So Thiamine vitamin is the vitamin B one. It assists in this process which transforms the pyruvate into acetal aldehyde as well as releasing this CO2 molecule shown here. Now, what about step two? Well, in step two we have a different enzyme and this enzyme is known as alcohol dehydrogenase. | Ethanol and Lactic Acid Fermentation .txt |
It assists in this process which transforms the pyruvate into acetal aldehyde as well as releasing this CO2 molecule shown here. Now, what about step two? Well, in step two we have a different enzyme and this enzyme is known as alcohol dehydrogenase. Now, like any dehydrogenase, alcohol dehydrogenase will essentially catalyze the transfer of a Hydride group from that NADH onto this acetolaldehyde. Now, if we examine the active side of the alcohol dehydrogenase we're going to see a zinc ion. And what that zinc ion does? | Ethanol and Lactic Acid Fermentation .txt |
Now, like any dehydrogenase, alcohol dehydrogenase will essentially catalyze the transfer of a Hydride group from that NADH onto this acetolaldehyde. Now, if we examine the active side of the alcohol dehydrogenase we're going to see a zinc ion. And what that zinc ion does? Well, first of all, it interacts with the active side of that enzyme. So it actually binds with residues on that active side. To be more specific, it binds with with 216 residues and one histidine residue. | Ethanol and Lactic Acid Fermentation .txt |
Well, first of all, it interacts with the active side of that enzyme. So it actually binds with residues on that active side. To be more specific, it binds with with 216 residues and one histidine residue. And once it binds it's able to actually interact with this substrate molecule. It polarizes this bond, weakens the bond and that's exactly what allows the Hydride to actually attack this carbon here and then allowing the H to go into this oxygen. And so ultimately we form ethanol and we regenerate that NAD plus. | Ethanol and Lactic Acid Fermentation .txt |
And once it binds it's able to actually interact with this substrate molecule. It polarizes this bond, weakens the bond and that's exactly what allows the Hydride to actually attack this carbon here and then allowing the H to go into this oxygen. And so ultimately we form ethanol and we regenerate that NAD plus. Now of course, because we form two Pyruvate molecules that means we have to multiply these two steps by two. And once we multiply these two steps by two and then we sum up all the processes, the ten processes of glycolysis and we sum these as well, this is the net equation that we get. And because we essentially regenerate that NAD plus, the NAD plus will cancel from both sides of the equation. | Ethanol and Lactic Acid Fermentation .txt |
Now of course, because we form two Pyruvate molecules that means we have to multiply these two steps by two. And once we multiply these two steps by two and then we sum up all the processes, the ten processes of glycolysis and we sum these as well, this is the net equation that we get. And because we essentially regenerate that NAD plus, the NAD plus will cancel from both sides of the equation. So that does not appear in this equation. And so the net equation of glycolysis following fermentation, specifically ethanol fermentation, this is our net equation. So a glucose goes in. | Ethanol and Lactic Acid Fermentation .txt |
So that does not appear in this equation. And so the net equation of glycolysis following fermentation, specifically ethanol fermentation, this is our net equation. So a glucose goes in. We use two ATP, two orthophosphates two H plus ions and that produces two ethanol molecules, two ATP molecules, two H so molecules and two carbon dioxide molecules that came from this process. So we multiply that by two and that's where that actually comes from. And notice the NAD pluses and Nadhs are canceled out because they are regenerated in this step. | Ethanol and Lactic Acid Fermentation .txt |
We use two ATP, two orthophosphates two H plus ions and that produces two ethanol molecules, two ATP molecules, two H so molecules and two carbon dioxide molecules that came from this process. So we multiply that by two and that's where that actually comes from. And notice the NAD pluses and Nadhs are canceled out because they are regenerated in this step. Now what about lactic acid fermentation? So lactic acid fermentation is used by many prokaryotic cells so bacterial cells that we're going to discuss in just a moment as well as many eukaryotic cells. In fact, the cells of our body also use under some circumstances, lactic acid fermentation. | Ethanol and Lactic Acid Fermentation .txt |
Now what about lactic acid fermentation? So lactic acid fermentation is used by many prokaryotic cells so bacterial cells that we're going to discuss in just a moment as well as many eukaryotic cells. In fact, the cells of our body also use under some circumstances, lactic acid fermentation. For instance, when we're exercising strenuously the skeletal muscles at some point will not be able to get enough oxygen and at that moment in time they have to switch to the process of lactic acid fermentation because that allows them to continually generate those ATP molecules. And so that's exactly what allows the buildup of lactate. So lactic acid in our body and that eventually causes fatigue. | Ethanol and Lactic Acid Fermentation .txt |
For instance, when we're exercising strenuously the skeletal muscles at some point will not be able to get enough oxygen and at that moment in time they have to switch to the process of lactic acid fermentation because that allows them to continually generate those ATP molecules. And so that's exactly what allows the buildup of lactate. So lactic acid in our body and that eventually causes fatigue. So many prokaryotic and eukaryotic organisms undergo lactic acid fermentation. In fact, when the two supply runs low in our cells they use this process to regenerate the NAD plus. And this process is a single step process that essentially consists of a well, not a single step process but it's more complicated than that. | Ethanol and Lactic Acid Fermentation .txt |
So many prokaryotic and eukaryotic organisms undergo lactic acid fermentation. In fact, when the two supply runs low in our cells they use this process to regenerate the NAD plus. And this process is a single step process that essentially consists of a well, not a single step process but it's more complicated than that. But we can think of it as being one step in the sense that here we have two steps but here we have one step. So essentially this process is catalyzed by an enzyme known as lactate dehydrogenase. And again, just like this dehydrogenase and the dehydrogenase that was used in step six of glycolysis. | Ethanol and Lactic Acid Fermentation .txt |
But we can think of it as being one step in the sense that here we have two steps but here we have one step. So essentially this process is catalyzed by an enzyme known as lactate dehydrogenase. And again, just like this dehydrogenase and the dehydrogenase that was used in step six of glycolysis. This dehydrogenase, like any dehydrogenase, will essentially catalyze the movement, the transfer of a Hydride group from one molecule to another. In this case it's from this NADH onto this pyruvate molecule. And so ultimately what happens is the Hydride from this essentially goes on, attacks this carbon and then the H is picked up by the oxygen and so we form this lactate. | Ethanol and Lactic Acid Fermentation .txt |
This dehydrogenase, like any dehydrogenase, will essentially catalyze the movement, the transfer of a Hydride group from one molecule to another. In this case it's from this NADH onto this pyruvate molecule. And so ultimately what happens is the Hydride from this essentially goes on, attacks this carbon and then the H is picked up by the oxygen and so we form this lactate. Now if an H is picked up by this, that is what we call lactic acid. So lactate is the conjugate base of lactic acid. So we see that the lactate dehydrogenase catalyze the transfer of the hydrad group and so ultimately we regenerate that NAD plus. | Ethanol and Lactic Acid Fermentation .txt |
Now if an H is picked up by this, that is what we call lactic acid. So lactate is the conjugate base of lactic acid. So we see that the lactate dehydrogenase catalyze the transfer of the hydrad group and so ultimately we regenerate that NAD plus. And again we have to multiply this by two because we have two pyruvate molecules coming in from the process of glycolysis. And again, if we sum up all those reactions in glycolysis and this reaction, this is the net equation that we get. And notice it's slightly different than this equation here because here we produce carbon dioxide, but here we don't have carbon dioxide and we also don't have the two H plus. | Ethanol and Lactic Acid Fermentation .txt |
And again we have to multiply this by two because we have two pyruvate molecules coming in from the process of glycolysis. And again, if we sum up all those reactions in glycolysis and this reaction, this is the net equation that we get. And notice it's slightly different than this equation here because here we produce carbon dioxide, but here we don't have carbon dioxide and we also don't have the two H plus. So here it becomes glucose plus two ADP plus two ortho phosphates produces two lactate, two ATP and two water molecules. And as I mentioned just a moment ago, during strain use exercise, our skeletal muscle cells may not receive an adequate supply of oxygen and these cells will begin to undergo lactic acid fermentation to generate those ATP molecules quickly and effectively. And in that case, there's a build up of lactate so lactic acid and that causes fatigue. | Ethanol and Lactic Acid Fermentation .txt |
So here it becomes glucose plus two ADP plus two ortho phosphates produces two lactate, two ATP and two water molecules. And as I mentioned just a moment ago, during strain use exercise, our skeletal muscle cells may not receive an adequate supply of oxygen and these cells will begin to undergo lactic acid fermentation to generate those ATP molecules quickly and effectively. And in that case, there's a build up of lactate so lactic acid and that causes fatigue. Now, our own cells are not the only cells that utilize lactic acid lactic acid fermentation. Many bacterial cells that infect our body and many other organisms utilize lactic acid fermentation. For instance, three important bacterial cells that utilize lactic acid fermentation to basically generate ATP are the following. | Ethanol and Lactic Acid Fermentation .txt |
Now, our own cells are not the only cells that utilize lactic acid lactic acid fermentation. Many bacterial cells that infect our body and many other organisms utilize lactic acid fermentation. For instance, three important bacterial cells that utilize lactic acid fermentation to basically generate ATP are the following. So we have Closetridium tetani, closetium botulinum and Closetridium per fringes. So Closetridium tetani is that bacteriosat that causes tetanus in humans, also known as lockjaw. We have Clostridium botulinum, which is actually the most toxic bacteria in the world. | Ethanol and Lactic Acid Fermentation .txt |
So we have Closetridium tetani, closetium botulinum and Closetridium per fringes. So Closetridium tetani is that bacteriosat that causes tetanus in humans, also known as lockjaw. We have Clostridium botulinum, which is actually the most toxic bacteria in the world. And interestingly, this is the same bacteria that is used for the plastic surgery we call botox. So this is the same exact bacteria that is used to make us supposedly prettier. And then we have the Clostridium preferring. | Ethanol and Lactic Acid Fermentation .txt |
And interestingly, this is the same bacteria that is used for the plastic surgery we call botox. So this is the same exact bacteria that is used to make us supposedly prettier. And then we have the Clostridium preferring. And by the way, this also causes botulism in humans. And so Clostridium, so Clostridium, there should be an odd there. Clostridium so Clostridium preferrings is the disease, is that bacteria that causes gangrene when we have wounds or some types of cuts. | Ethanol and Lactic Acid Fermentation .txt |
And by the way, this also causes botulism in humans. And so Clostridium, so Clostridium, there should be an odd there. Clostridium so Clostridium preferrings is the disease, is that bacteria that causes gangrene when we have wounds or some types of cuts. So these can be very, very dangerous bacteria. And these three types of bacterial cells essentially are obligate anaerobes. And what that means is they cannot survive in the presence of oxygen and they only utilize fermentation to produce their ATP molecules. | Ethanol and Lactic Acid Fermentation .txt |
So these can be very, very dangerous bacteria. And these three types of bacterial cells essentially are obligate anaerobes. And what that means is they cannot survive in the presence of oxygen and they only utilize fermentation to produce their ATP molecules. So the takeaway lesson from this lecture is the fact that glycolysis by itself is not a perfect process. And if it's left alone, then it will eventually end because it will run out of that supply of the coenzyme NAD plus. And so to regenerate that NAD plus and to make sure that the NAD plus is continually used and glycolysis is continually taking place in producing ATP molecules in our cells, we have to metabolize the Pyruvate under aerobic conditions. | Ethanol and Lactic Acid Fermentation .txt |
So the takeaway lesson from this lecture is the fact that glycolysis by itself is not a perfect process. And if it's left alone, then it will eventually end because it will run out of that supply of the coenzyme NAD plus. And so to regenerate that NAD plus and to make sure that the NAD plus is continually used and glycolysis is continually taking place in producing ATP molecules in our cells, we have to metabolize the Pyruvate under aerobic conditions. That's when the citric acid takes a citric acid cycle takes place. Under anaerobic conditions, we have lactate fermentation or lactic acid fermentation, ethanol, fermentations, and also many other examples of fermentation processes that we're not going to discuss in this lecture. So in the next lecture, we're basically going to discuss how glucose molecules are not the only molecules that can undergo glycolysis. | Ethanol and Lactic Acid Fermentation .txt |
So we discussed allosteric regulation, we discussed covalent modification and proteolytic activation. Now, we're going to discuss yet another mechanism that our body uses. And this mechanism involves using different forms of the same type of enzyme to carry out a single specific type of reaction that basically takes place at different locations and different times in our body. And these different forms of the same type of enzyme are known as isozymes or ISO enzymes. So isozymes generally allow our body to regulate the same type of biochemical reaction that takes place at different locations and sometimes at different times. Now, before we actually look at a specific example of ISO enzymes, let's generalize what we know about isozymes or ISO enzymes. | Isozymes .txt |
And these different forms of the same type of enzyme are known as isozymes or ISO enzymes. So isozymes generally allow our body to regulate the same type of biochemical reaction that takes place at different locations and sometimes at different times. Now, before we actually look at a specific example of ISO enzymes, let's generalize what we know about isozymes or ISO enzymes. So once again, isozymes are these different forms of the same type of enzyme and these isozymes come from different genes. And what that means is they're going to have different amino acid sequences and different threedimensional structures, but they will catalyze the same type of biochemical reaction. So we see that ISMES arise from different genes, they have different sequences of amino acids and what that means is they will generally have different biochemical properties. | Isozymes .txt |
So once again, isozymes are these different forms of the same type of enzyme and these isozymes come from different genes. And what that means is they're going to have different amino acid sequences and different threedimensional structures, but they will catalyze the same type of biochemical reaction. So we see that ISMES arise from different genes, they have different sequences of amino acids and what that means is they will generally have different biochemical properties. And this is exactly what allows us to actually separate or purify mixtures of isozymes. Now, not only that, but Icimes also generally have different enzyme kinetics. So they differ in the Km value, the mechanism constant in a turnover number Kcat, and they also differ in things like the V max, the maximum velocity at which the enzyme operates. | Isozymes .txt |
And this is exactly what allows us to actually separate or purify mixtures of isozymes. Now, not only that, but Icimes also generally have different enzyme kinetics. So they differ in the Km value, the mechanism constant in a turnover number Kcat, and they also differ in things like the V max, the maximum velocity at which the enzyme operates. And isozymes are also typically regulated by different types of regulatory molecules, different types of allosteric effectors. So, inside our body we have many different types of cells. And these different types of cells basically exist under slightly different conditions. | Isozymes .txt |
And isozymes are also typically regulated by different types of regulatory molecules, different types of allosteric effectors. So, inside our body we have many different types of cells. And these different types of cells basically exist under slightly different conditions. Yet all these different types of cells have to carry out identical types of reactions. For instance, to see what we mean, let's imagine we have a cardiac muscle cell and a skeleton muscle cell. So we have two different types of cells that are found at two different types of locations. | Isozymes .txt |
Yet all these different types of cells have to carry out identical types of reactions. For instance, to see what we mean, let's imagine we have a cardiac muscle cell and a skeleton muscle cell. So we have two different types of cells that are found at two different types of locations. So cardiac muscle cells found in the heart and skeleton muscle cell is basically found around the bone. Now, cardiac muscle cells are found in a rich oxygen environment, but it's the skeleton muscle cell that is found usually in a lower oxygen environment. But both of these different types of cells found under different conditions must carry out the same type of biochemical process, namely let's say glycolysis. | Isozymes .txt |
So cardiac muscle cells found in the heart and skeleton muscle cell is basically found around the bone. Now, cardiac muscle cells are found in a rich oxygen environment, but it's the skeleton muscle cell that is found usually in a lower oxygen environment. But both of these different types of cells found under different conditions must carry out the same type of biochemical process, namely let's say glycolysis. So they both have to be able to metabolize glycolysis glucose in the process of glycolysis. And in fact, skeleton muscle cells and cardiac muscle cells actually use ISMES in the process of glycolysis. So remember a specific type of enzyme that we spoke of previously. | Isozymes .txt |
So they both have to be able to metabolize glycolysis glucose in the process of glycolysis. And in fact, skeleton muscle cells and cardiac muscle cells actually use ISMES in the process of glycolysis. So remember a specific type of enzyme that we spoke of previously. So we discussed lactate dehydrogenase and we said that lactate dehydrogenase is an enzyme that is basically involved in glucose metabolism. And more specifically, what it does is it transforms pyruvate into lactic acid, it reduces pyruvate into lactic acid and that at the same time oxidizes NADH into NAD plus. And what that allows us to do is it allows us to regenerate NAD plus. | Isozymes .txt |
So we discussed lactate dehydrogenase and we said that lactate dehydrogenase is an enzyme that is basically involved in glucose metabolism. And more specifically, what it does is it transforms pyruvate into lactic acid, it reduces pyruvate into lactic acid and that at the same time oxidizes NADH into NAD plus. And what that allows us to do is it allows us to regenerate NAD plus. And so that means we can basically restart another cycle of glycolysis. So we see that lactate dehydrogenase catalyzes the reduction of pyruvate into lactic acid at the same time and oxidizes NADH into NAD plus. Now, if we examine the quadrantary structure of lactate dehydrogenase LDH, we're going to see that it consists of four individual polypeptide chains. | Isozymes .txt |
And so that means we can basically restart another cycle of glycolysis. So we see that lactate dehydrogenase catalyzes the reduction of pyruvate into lactic acid at the same time and oxidizes NADH into NAD plus. Now, if we examine the quadrantary structure of lactate dehydrogenase LDH, we're going to see that it consists of four individual polypeptide chains. And inside our body, in the human body, we have two types of these polypeptide chains that can constitute lactate dehydrogenase. So humans have two isozymic chains for lactate dehydrogenase. We have the H ISome chain and we have the misozyme chain. | Isozymes .txt |
And inside our body, in the human body, we have two types of these polypeptide chains that can constitute lactate dehydrogenase. So humans have two isozymic chains for lactate dehydrogenase. We have the H ISome chain and we have the misozyme chain. And it's the H isime chain that is expressed predominantly in high concentration in the cardiac muscle cell. And it's the mike chain that is expressed in high concentration predominantly in the skeletal muscle cell. So if we examine the lactate dehydrogenase in skeletal muscle cells, we're basically going to find a quaternary structure that consists of these four individual chains, where these four individual chains are all the Mi design chains. | Isozymes .txt |
And it's the H isime chain that is expressed predominantly in high concentration in the cardiac muscle cell. And it's the mike chain that is expressed in high concentration predominantly in the skeletal muscle cell. So if we examine the lactate dehydrogenase in skeletal muscle cells, we're basically going to find a quaternary structure that consists of these four individual chains, where these four individual chains are all the Mi design chains. So each one of these red chains is basically that Mi design chain. On the other hand, if we study the cardiac muscle cells, we're going to see the coronary structure of the LDH basically consists of four individual H I design chains and these are shown in purple. So this lactate dehydrogenase, which is basically denoted with H four, where H means we have the H ISome and four means we have four of these individual A chains. | Isozymes .txt |
So each one of these red chains is basically that Mi design chain. On the other hand, if we study the cardiac muscle cells, we're going to see the coronary structure of the LDH basically consists of four individual H I design chains and these are shown in purple. So this lactate dehydrogenase, which is basically denoted with H four, where H means we have the H ISome and four means we have four of these individual A chains. So we have this lactate dehydrogenase is made up of four A chains and it's found in cardiac muscle cells, while the M four, which basically consists of these four individual M isotime chains, makes up the LDH that predominates in skeletal muscle cells. So we see that it's this molecule, the M four, that operates at a maximum efficiency inside skeleton muscle cells where we typically have a lower oxygen concentration. But it's this purple H four LDH molecule that predominates in cardiac muscle cell which operates at a maximum efficiency when there's a high concentration of oxygen, as we typically find in the heart, in the cardiac muscle cell. | Isozymes .txt |
So we have this lactate dehydrogenase is made up of four A chains and it's found in cardiac muscle cells, while the M four, which basically consists of these four individual M isotime chains, makes up the LDH that predominates in skeletal muscle cells. So we see that it's this molecule, the M four, that operates at a maximum efficiency inside skeleton muscle cells where we typically have a lower oxygen concentration. But it's this purple H four LDH molecule that predominates in cardiac muscle cell which operates at a maximum efficiency when there's a high concentration of oxygen, as we typically find in the heart, in the cardiac muscle cell. So these are what isoenzymes are. So isozymes or isoenzymes are these multiple different forms of the same type of enzyme that catalyzes the same type of biochemical reaction that takes place at different locations and ore at different times. Now let's see how we can apply this to our body, to the field of medicine. | Isozymes .txt |
So these are what isoenzymes are. So isozymes or isoenzymes are these multiple different forms of the same type of enzyme that catalyzes the same type of biochemical reaction that takes place at different locations and ore at different times. Now let's see how we can apply this to our body, to the field of medicine. So remember, that a heart attack, also known as a myocardial infraction is basically the condition by which we have a partial blockage of the blood flow to the heart of our body. For instance, previously we discussed that if we block if we create some type of embolism inside the coronary artery of our heart, that will lead to a heart attack. Now, if there's a partial blockage of blood flow to the heart, that will cause damage inside the cardiac muscle of the heart. | Isozymes .txt |
So remember, that a heart attack, also known as a myocardial infraction is basically the condition by which we have a partial blockage of the blood flow to the heart of our body. For instance, previously we discussed that if we block if we create some type of embolism inside the coronary artery of our heart, that will lead to a heart attack. Now, if there's a partial blockage of blood flow to the heart, that will cause damage inside the cardiac muscle of the heart. And if the cardiac muscle cell is damaged, it will begin releasing its internal components, and that includes releasing the H four LDH molecule. Now, as the cardiac muscle is damaged, releasing the H four LDH into the blood will increase the relative concentration of this molecule inside of the blood. And this molecule is typically not found in a specific high concentration inside our blood. | Isozymes .txt |
And if the cardiac muscle cell is damaged, it will begin releasing its internal components, and that includes releasing the H four LDH molecule. Now, as the cardiac muscle is damaged, releasing the H four LDH into the blood will increase the relative concentration of this molecule inside of the blood. And this molecule is typically not found in a specific high concentration inside our blood. So physicians can basically test for the presence of elevated H four concentration in the blood. And this can basically help them show or help them discover the fact that this individual has experienced a myocardial infraction or a heart attack. So we see that not only can our body control and regulate enzyme activity by using these three different types of mechanisms, it can also use is and isozymes. | Isozymes .txt |
So let's say this is the outside, this is the inside. And because we have a bilayer membrane, we have two layers. Let's call this the outer leaflet that points towards the outside. This the inner leaflet that point towards the side of plasma. Now, if we take take a line and we draw a line that separates the membrane in half, like so, we'll see that this side is not the same as this side. These two leaflets are not identical. | Asymmetry of Cell Membrane .txt |
This the inner leaflet that point towards the side of plasma. Now, if we take take a line and we draw a line that separates the membrane in half, like so, we'll see that this side is not the same as this side. These two leaflets are not identical. And that implies that the plasma membrane is asymmetric. So the two leaflets, the two sides of the membrane are structurally and functionally not the same. Now, what factors contribute to the asymmetry of the plasma membrane? | Asymmetry of Cell Membrane .txt |
And that implies that the plasma membrane is asymmetric. So the two leaflets, the two sides of the membrane are structurally and functionally not the same. Now, what factors contribute to the asymmetry of the plasma membrane? So we have to consider three things. Number one is there is a difference in the composition of the proteins and lipids and carbohydrates found on the two sides of the membrane. So for instance, in this particular case, we have glycolipids and glycoproteins on this side that we don't find on the other side. | Asymmetry of Cell Membrane .txt |
So we have to consider three things. Number one is there is a difference in the composition of the proteins and lipids and carbohydrates found on the two sides of the membrane. So for instance, in this particular case, we have glycolipids and glycoproteins on this side that we don't find on the other side. And likewise, we have the peripheral protein that we find on this side and don't find on the other side. Number two is we have asymmetry because of the difference in the positioning and the orientation of proteins. For instance, if we look at this transmembrane protein, this is oriented in such a way so that this side only contains the peripheral component protein and not this side. | Asymmetry of Cell Membrane .txt |
And likewise, we have the peripheral protein that we find on this side and don't find on the other side. Number two is we have asymmetry because of the difference in the positioning and the orientation of proteins. For instance, if we look at this transmembrane protein, this is oriented in such a way so that this side only contains the peripheral component protein and not this side. And number three is there is asymmetry as a result of a difference in the enzymatic activities of the two sides. Basically, those reactions that take place on this side of the membrane don't take place on this side and vice versa. For instance, if a protein needs to use ATP molecules, the ATP molecules are only found in the cytoplasm. | Asymmetry of Cell Membrane .txt |
And number three is there is asymmetry as a result of a difference in the enzymatic activities of the two sides. Basically, those reactions that take place on this side of the membrane don't take place on this side and vice versa. For instance, if a protein needs to use ATP molecules, the ATP molecules are only found in the cytoplasm. And so that protein component can only interact with the ATP from the cytoplasmic side of the membrane, as we'll discuss in more detail in just a moment. Now, why is asymmetry so prevalent? So every single plasma membrane basically is asymmetric. | Asymmetry of Cell Membrane .txt |
And so that protein component can only interact with the ATP from the cytoplasmic side of the membrane, as we'll discuss in more detail in just a moment. Now, why is asymmetry so prevalent? So every single plasma membrane basically is asymmetric. Why? Well, asymmetry is actually crucial for the proper functioning of that membrane. So to see what we mean to demonstrate, let's study the ATP or the sodium potassium ATP pump found in every single cell of our body. | Asymmetry of Cell Membrane .txt |
Why? Well, asymmetry is actually crucial for the proper functioning of that membrane. So to see what we mean to demonstrate, let's study the ATP or the sodium potassium ATP pump found in every single cell of our body. So this is what it basically looks like. And what it is is it's this pump that utilizes ATP molecules to create an electrochemical gradient and it pumps the sodium ions to the outside and the potassium ions to the inside. Now, because it uses ATP molecules, ATP molecules are only found in the cytoplasm. | Asymmetry of Cell Membrane .txt |
So this is what it basically looks like. And what it is is it's this pump that utilizes ATP molecules to create an electrochemical gradient and it pumps the sodium ions to the outside and the potassium ions to the inside. Now, because it uses ATP molecules, ATP molecules are only found in the cytoplasm. And what that means is this protein has to be positioned in the proper orientation so that the proper side can actually interact with the ATP molecule. And this has to be positioned in the proper orientation because we want to move the sodium this way and the potassium this way, and not in the opposite direction. And so we see that the proper positioning of this protein within the membrane determines its functionality. | Asymmetry of Cell Membrane .txt |
And what that means is this protein has to be positioned in the proper orientation so that the proper side can actually interact with the ATP molecule. And this has to be positioned in the proper orientation because we want to move the sodium this way and the potassium this way, and not in the opposite direction. And so we see that the proper positioning of this protein within the membrane determines its functionality. And this cell as a whole must be able to actually use the ATP and pump these in the proper directionality to basically establish that electrochemical gradient. And so we see that asymmetry is very important to the functionality of the cell membrane. Now, when we synthesize these proteins in the ribosomes of our cell, these proteins as well as lipids actually are placed into the membrane in an asymmetric fashion. | Asymmetry of Cell Membrane .txt |
And this cell as a whole must be able to actually use the ATP and pump these in the proper directionality to basically establish that electrochemical gradient. And so we see that asymmetry is very important to the functionality of the cell membrane. Now, when we synthesize these proteins in the ribosomes of our cell, these proteins as well as lipids actually are placed into the membrane in an asymmetric fashion. So we essentially place these proteins asymmetrically. And so we create this asymmetry in the membrane as a result of the difference in the composition and the positioning and orientation of the proteins. But the question is, how is this asymmetry? | Asymmetry of Cell Membrane .txt |
So we essentially place these proteins asymmetrically. And so we create this asymmetry in the membrane as a result of the difference in the composition and the positioning and orientation of the proteins. But the question is, how is this asymmetry? How is this asymmetric nature of the membrane actually retained? How is it preserved over time? So what exactly prevents, for instance, these two proteins from actually oring themselves and flipping to the other side? | Asymmetry of Cell Membrane .txt |
How is this asymmetric nature of the membrane actually retained? How is it preserved over time? So what exactly prevents, for instance, these two proteins from actually oring themselves and flipping to the other side? Well, basically, when we discussed flip flopping, or also known as transverse diffusion, we said that proteins cannot actually rotate from one leaflet to the other leaflet, and that's because when they rotate, that is energetically unfavorable, because the proteins contain extensive hydrophilic. So polar regions, when they rotate, that means the polar regions must interact with the hydrophobic core of the membrane. And that is too energetically unfavorable. | Asymmetry of Cell Membrane .txt |
Well, basically, when we discussed flip flopping, or also known as transverse diffusion, we said that proteins cannot actually rotate from one leaflet to the other leaflet, and that's because when they rotate, that is energetically unfavorable, because the proteins contain extensive hydrophilic. So polar regions, when they rotate, that means the polar regions must interact with the hydrophobic core of the membrane. And that is too energetically unfavorable. The energy is very high for that reaction and it doesn't actually take place. And so we see that proteins do not flip flop. They cannot rotate or move from one leaflet to the opposing leaflet. | Asymmetry of Cell Membrane .txt |
The energy is very high for that reaction and it doesn't actually take place. And so we see that proteins do not flip flop. They cannot rotate or move from one leaflet to the opposing leaflet. And so we see that this is precisely what prevents the asymmetry from being lost. So the membrane asymmetry is preserved over long periods of time, because membrane proteins do not actually rotate from one side of the membrane to the other side of the membrane, because this is too energetically unfavorable. Now, in addition, what also retains or preserves the asymmetry of the membrane is the fact that membranes are always constructed from preexisting membranes, and those preexisting membranes are always asymmetric. | Asymmetry of Cell Membrane .txt |
And so we see that this is precisely what prevents the asymmetry from being lost. So the membrane asymmetry is preserved over long periods of time, because membrane proteins do not actually rotate from one side of the membrane to the other side of the membrane, because this is too energetically unfavorable. Now, in addition, what also retains or preserves the asymmetry of the membrane is the fact that membranes are always constructed from preexisting membranes, and those preexisting membranes are always asymmetric. So, in the same way that to actually create a cell, we have to begin with a cell, to create a membrane, we have to begin with the membrane. So when we're building our cell membrane, we build it by essentially expanding the preexisting membrane. And that preexisting membrane basically was asymmetric to begin with. | Asymmetry of Cell Membrane .txt |
So, in the same way that to actually create a cell, we have to begin with a cell, to create a membrane, we have to begin with the membrane. So when we're building our cell membrane, we build it by essentially expanding the preexisting membrane. And that preexisting membrane basically was asymmetric to begin with. So we see that, in addition, asymmetry is also preserved because membranes always arise and grow and extend from preexisting membranes, which are asymmetric to begin with. Now, in our discussion here, we said that the difference in the composition of not only the proteins but also the lipids basically gives this membrane the property of asymmetry. So now let's move on from proteins to lipids. | Asymmetry of Cell Membrane .txt |
So we see that, in addition, asymmetry is also preserved because membranes always arise and grow and extend from preexisting membranes, which are asymmetric to begin with. Now, in our discussion here, we said that the difference in the composition of not only the proteins but also the lipids basically gives this membrane the property of asymmetry. So now let's move on from proteins to lipids. So we know that just like proteins are synthesized and eventually placed into the membrane in an asymmetric fashion, lipids are also synthesized and inserting to the membrane asymmetrically. However, the thing about lipids is, so fossil lipids is they can actually flip flop, they can actually rotate. And so what that implies is, unlike the absolute configuration, unlike the absolute asymmetry of the proteins in the membrane that basically do not change because they cannot flip flop, the asymmetry of the membrane due to the lipids does in fact change over time. | Asymmetry of Cell Membrane .txt |
So we know that just like proteins are synthesized and eventually placed into the membrane in an asymmetric fashion, lipids are also synthesized and inserting to the membrane asymmetrically. However, the thing about lipids is, so fossil lipids is they can actually flip flop, they can actually rotate. And so what that implies is, unlike the absolute configuration, unlike the absolute asymmetry of the proteins in the membrane that basically do not change because they cannot flip flop, the asymmetry of the membrane due to the lipids does in fact change over time. It is not absolute because these lipids can actually rotate, can actually flip flop from one leaflet to the other. So we see that however, lipids such as fossil lipids can actually flip flop and therefore the asymmetry of the fossil lipids in that membrane does not remain absolute, it changes over time. However, we know that flip flopping of fossil lipids actually takes place very, very slowly because it is also energetically unfavorable. | Asymmetry of Cell Membrane .txt |
It is not absolute because these lipids can actually rotate, can actually flip flop from one leaflet to the other. So we see that however, lipids such as fossil lipids can actually flip flop and therefore the asymmetry of the fossil lipids in that membrane does not remain absolute, it changes over time. However, we know that flip flopping of fossil lipids actually takes place very, very slowly because it is also energetically unfavorable. In fact, certain lipids, such as Glycolipids that contain very large components that are polar, cannot actually rotate because of those polar interactions, because these polar interactions will be unstabilized when they interact with that core hydrophobic region. And so, just like proteins, glycolipids cannot actually flip flop or rotate. Now, nevertheless, we see that lipids such as glycolipids and spingolipids can and do lead to asymmetry of the membrane. | Asymmetry of Cell Membrane .txt |
In fact, certain lipids, such as Glycolipids that contain very large components that are polar, cannot actually rotate because of those polar interactions, because these polar interactions will be unstabilized when they interact with that core hydrophobic region. And so, just like proteins, glycolipids cannot actually flip flop or rotate. Now, nevertheless, we see that lipids such as glycolipids and spingolipids can and do lead to asymmetry of the membrane. So basically, because the flip flopping process takes place so long, takes place not so long, but takes place so slow, and because certain lipids, like Glycolipids can have actually rotate, we see that lipids also, just like proteins, actually contribute to the asymmetric nature of membranes. In fact, if we study the membranes of red blood cells, we'll see that the outside layer of the red blood cell membrane consists of these two lipids. So, these two lipids are found in high proportion on the outside of the membrane, while the inside contains these two lipids in high proportion. | Asymmetry of Cell Membrane .txt |
So the cell, including eukaryotic and prokaryotic cells, can use the DNA molecules to synthesize proteins and enzymes that are necessary for the cell survival. And in fact, whenever our cell or organism reproduces, each individual cell must replicate the DNA molecule and pass it down to the offspring. Now, what exactly is the composition of DNA? So, in the same way that proteins consist of individual units known as amino acids, DNA molecules are also polymers, meaning they consist of individual subunits known as nucleotides. And any given nucleotide consists of three parts. So we have a deoxyribo sugar, which is a five member sugar. | Introduction to DNA.txt |
So, in the same way that proteins consist of individual units known as amino acids, DNA molecules are also polymers, meaning they consist of individual subunits known as nucleotides. And any given nucleotide consists of three parts. So we have a deoxyribo sugar, which is a five member sugar. We have a nitrogenous base and we also have our phosphate group. Now, what exactly is the structure or arrangement of these three different types of sections or groups within our nucleotide? So this is one example of a nucleotide. | Introduction to DNA.txt |
We have a nitrogenous base and we also have our phosphate group. Now, what exactly is the structure or arrangement of these three different types of sections or groups within our nucleotide? So this is one example of a nucleotide. We have our base, the nitrogenous base, attached to our center sugar, which is also attached to our phosphate group. Now, there are four different types of nitrogenous bases. We have adenine, guanine, cytosine and thymine. | Introduction to DNA.txt |
We have our base, the nitrogenous base, attached to our center sugar, which is also attached to our phosphate group. Now, there are four different types of nitrogenous bases. We have adenine, guanine, cytosine and thymine. Now, adenine and guanine, or simply A and g are two types of nitrogenous bases that consist of two rings. And these types of nitrogenous bases that consist of two rings are known as purines. And notice thymine and cytosine or TNC consist of only a single ring structure. | Introduction to DNA.txt |
Now, adenine and guanine, or simply A and g are two types of nitrogenous bases that consist of two rings. And these types of nitrogenous bases that consist of two rings are known as purines. And notice thymine and cytosine or TNC consist of only a single ring structure. And these types of nitrogenous bases are known as pyrimidines. So let's look at the arrangement of our nucleotide and how the nucleotides bond to one another. So remember, in a protein we have amino acids that bond to one another via covalent bonds known as dipeptide or peptide bonds. | Introduction to DNA.txt |
And these types of nitrogenous bases are known as pyrimidines. So let's look at the arrangement of our nucleotide and how the nucleotides bond to one another. So remember, in a protein we have amino acids that bond to one another via covalent bonds known as dipeptide or peptide bonds. In the case of DNA, the individual subunits known as nucleotides bond to one another via bond, known as a phosphol diaster bond. So let's take a look at the following molecules. So we have one nucleotide and a second nucleotide. | Introduction to DNA.txt |
In the case of DNA, the individual subunits known as nucleotides bond to one another via bond, known as a phosphol diaster bond. So let's take a look at the following molecules. So we have one nucleotide and a second nucleotide. And notice that these two nucleotides bond to one another via the phosphol diaster bond. So we have the phosphorus atom and we also have the two aster bonds shown here. And that's exactly why it's called a phosphodia ester bond. | Introduction to DNA.txt |
And notice that these two nucleotides bond to one another via the phosphol diaster bond. So we have the phosphorus atom and we also have the two aster bonds shown here. And that's exactly why it's called a phosphodia ester bond. Now, notice that the bonding takes place between the third carbon of one sugar and the fifth carbon of the second sugar. And that's exactly why this is called a three to five bond. So this is our phosphol diester bond. | Introduction to DNA.txt |
Now, notice that the bonding takes place between the third carbon of one sugar and the fifth carbon of the second sugar. And that's exactly why this is called a three to five bond. So this is our phosphol diester bond. So notice that because there are four different types of nitrogenous bases, that means there are four different types of nucleotides. And it is very common to call our nucleotide by the type of nitrogenous base that it contains. So for example, because this nucleotide contains the guanine nitrogenous base, we simply call the nucleotide the guanine. | Introduction to DNA.txt |
So notice that because there are four different types of nitrogenous bases, that means there are four different types of nucleotides. And it is very common to call our nucleotide by the type of nitrogenous base that it contains. So for example, because this nucleotide contains the guanine nitrogenous base, we simply call the nucleotide the guanine. And because this contains the adenine nitrogenous base, this nucleotide can be called simply the adenine nucleotide. So we have one nucleotide bonds to a second nucleotide via this phosphodia ester bond. Now, DNA in cells, specifically in human cells, doesn't actually exist as a single strand of DNA. | Introduction to DNA.txt |
And because this contains the adenine nitrogenous base, this nucleotide can be called simply the adenine nucleotide. So we have one nucleotide bonds to a second nucleotide via this phosphodia ester bond. Now, DNA in cells, specifically in human cells, doesn't actually exist as a single strand of DNA. In fact, two strands of DNA that are complementary to one another actually bind to form a double stranded DNA. And that double stranded DNA forms a coil that we call the double helix. And the two single stranded DNAs bond to one another via a special type of dipole dipole bond known as hydrogen bonds. | Introduction to DNA.txt |
In fact, two strands of DNA that are complementary to one another actually bind to form a double stranded DNA. And that double stranded DNA forms a coil that we call the double helix. And the two single stranded DNAs bond to one another via a special type of dipole dipole bond known as hydrogen bonds. So the thing that holds our two strands of DNA together to form our double helix are hydrogen bondings or hydrogen bonds between adjacent or opposite nucleotide, specifically our nitrogenous basis. So we have this nucleotide, which is right next to this nucleotide, and the bonding takes place between our adjacent or complementary nitrogenous bases. So guanine always forms hydrogen bonds with cytosine, while our Adamine always forms hydrogen bonds with arithymine. | Introduction to DNA.txt |
So the thing that holds our two strands of DNA together to form our double helix are hydrogen bondings or hydrogen bonds between adjacent or opposite nucleotide, specifically our nitrogenous basis. So we have this nucleotide, which is right next to this nucleotide, and the bonding takes place between our adjacent or complementary nitrogenous bases. So guanine always forms hydrogen bonds with cytosine, while our Adamine always forms hydrogen bonds with arithymine. And notice in the case of guanine and cytosine, we have three hydrogen bonds. And in the case of adenine and thymine, we only have two of these hydrogen bonds. So that means the guanine cytosine pair forms a more stable attraction than our adenine, thymine. | Introduction to DNA.txt |
And notice in the case of guanine and cytosine, we have three hydrogen bonds. And in the case of adenine and thymine, we only have two of these hydrogen bonds. So that means the guanine cytosine pair forms a more stable attraction than our adenine, thymine. So if a given DNA molecule contains more guanine cytosine pairs, that means the bonding between our two single stranded DNA molecules is stronger. Now, one other important thing that we have to mention about the double helix is the directionality of our single stranded DNA. So let's take a look at this single stranded DNA that only consists of two nucleotides. | Introduction to DNA.txt |
So if a given DNA molecule contains more guanine cytosine pairs, that means the bonding between our two single stranded DNA molecules is stronger. Now, one other important thing that we have to mention about the double helix is the directionality of our single stranded DNA. So let's take a look at this single stranded DNA that only consists of two nucleotides. So we have the guanine and the anine. Notice that the guanine begins on our five carbon and it goes down to our three carbon, while the second single stranded DNA begins with the third carbon and goes down to the fifth carbon. And this type of opposite or reverse arrangement is known as antiparallel. | Introduction to DNA.txt |
So we have the guanine and the anine. Notice that the guanine begins on our five carbon and it goes down to our three carbon, while the second single stranded DNA begins with the third carbon and goes down to the fifth carbon. And this type of opposite or reverse arrangement is known as antiparallel. That is, the two single stranded DNA, this one and this one run in the parallel direction, but they run in the opposite direction, meaning that this goes from the five to the three carbon and this runs from the three to the five carbon. So once again, we have our notice that if the first strand runs in the five three direction, then the complementary strand must run in the reverse three to five direction. And this type of arrangement is known as antiparallel. | Introduction to DNA.txt |
That is, the two single stranded DNA, this one and this one run in the parallel direction, but they run in the opposite direction, meaning that this goes from the five to the three carbon and this runs from the three to the five carbon. So once again, we have our notice that if the first strand runs in the five three direction, then the complementary strand must run in the reverse three to five direction. And this type of arrangement is known as antiparallel. And the reason the two DNA molecules run antiparallel is to ensure that the bonding between our nitrogenous bases is exactly right, so that we create strong bonds between our two DNA molecules and so that our double stranded DNA molecule basically doesn't unzip itself spontaneously. So this is a slightly better description of our DNA molecule because this shows our double helix structure. So we have the blue and our purple strand. | Introduction to DNA.txt |
And the reason the two DNA molecules run antiparallel is to ensure that the bonding between our nitrogenous bases is exactly right, so that we create strong bonds between our two DNA molecules and so that our double stranded DNA molecule basically doesn't unzip itself spontaneously. So this is a slightly better description of our DNA molecule because this shows our double helix structure. So we have the blue and our purple strand. So the blue one begins at the five end and goes all the way to the three N, while the pink begins at the three N and goes all the way to the five end. And this is what we mean by the antiparallel directionality, where one of our single stranded DNA runs from the five to three, while the other one runs from the three to five. Now, one other thing that we have to notice is that the sugar as well as the phosphate within our double stranded DNA points outside of that DNA while inside that double stranded DNA double helix structure, we have our nitrogenous basis. | Introduction to DNA.txt |