Transcript for:
Glycolysis

Alright Ninja Nerds, in this video we're going to talk about glycolysis. So in short, just a little definition about glycolysis, is they're going to oxidize a molecule called glucose. So you know glucose is a six carbon molecule, it's basically a monosaccharide which is just a fancy word for sugar. So glucose is a six carbon molecule and we're getting that from our diet. We'll talk about how exactly we're getting it from our diet in the digestive system. But for right now, we're just going to say that we're bringing glucose into our cells, which is again is a six carbon molecule. And we're going to oxidize him through various steps, about 10 steps to eventually convert that into pyruvate, at least two pyruvates, which is two, three carbon molecules. But the question is, How can we get this glucose, this six carbon molecule into this cell? How do we do that? Because you know glucose, so again what is this molecule right here guys? This molecule right here is specifically called glucose. Let's actually write it in red, make it nice and purry. Again this is called glucose. So glucose is our sixth carbon molecule. We're denoting that by these circles. That's one, two, three, four, five, six. Thing is though, glucose is actually going to be a water soluble solute. In other words, it can't actually move through the cell membrane by diffusion, by passively. It has to come through some type of transporter, a specialized transporter. These specialized transporters are called Glut Transporter. So again, what is this one called here? It's specifically called a Glut Transporter. But... Let's say that we're having this occur in different organs. You know glut transporters? You know glut is glucose transporter. They're the ones that are bringing this glucose into the cell, but they're not just one direction, they're bi-directional. So at the same time, they can bring glucose from actually, what? Inside of the cell to outside of the cell. But there's many different types of glut receptors. One way that I like to just easily, quickly remember all of them, it's a helpful mnemonic in my opinion, it's up to you guys whether you guys like it here, but it goes like this. See, right like this. B. be, be, okay, kids lips are, but this doesn't matter, okay, pink mother, father. Okay, so it's just a little quick way that it helps me to give you basically categorize my glut receptors and it's gonna go in a specific order. So this is actually gonna be for glut one, this is gonna be for glut two. The pink is going to be 4, glut 3. And mother and father is going to be 4, glut 4. Now what does each one of these things mean? So BBB, the first B I like to remember is blood. But specifically what type of blood? I mean the red blood cells. So on the red blood cells plasma membrane they have a glut 1 receptor. I also like to remember B for baby. We don't say baby, we say the fetus. So the fetus is actually going to have GLUT1 receptors. Okay? And then the last one is the blood-brain barrier. So blood, brain, Barrier. You know that's the actual separation between the actual vessels and the pia mater and the neural tissue with the astrocytes around them. We'll talk about that more in the neurophysiology. But again, these are the three easy ones to remember for glut 1. BBB. Blood, specifically red blood cells. Baby, but I like that we actually be technical and say fetus. And the third one is BBB. Blood-Brain Barrier. Alright, what about the second one? So I like to highlight. Here, KI, I like to highlight the LI, and I like to highlight the P and the S, right? So what does that give me? Well, the KI is going to give me kidney. So the kidney has GLUT2 receptors. The LI is for the liver, and the PS is for the pancreas. There is other tissues. These aren't all of them. Obviously, you can also find within the gastrointestinal tract, there is certain types of GLUT2 receptors also. But anyway, glut 3, pink. So I like to remember the P right there, the P for placenta, the N for neuron, and another K for kidney. So it's not that bad, right, when you think about it. So again, what is it going to be? It's going to be placenta. And then we're going to have neurons, are going to have these glut 3 receptors. Don't get that confused with the actual glut 1, which is for the blood brain barrier. Okay, that's different. Okay, because this is going to be where the astrocytes are, right? Between the blood vessels and the astrocytes. So don't get that confused with the actual neuron cell membrane. Okay, then K is going to be for, again, the kidney. And then the last one, mother-father. I like to remember M for muscle and F for adipose or fat. So again, what would this last one be here? Mother and father is going to be, specifically we'll just do these individually. Mother is for muscle. and father is for fat. But we should be technical and say adipose. Okay? So the whole purpose of this is just helping you guys to realize that there's many different glut transporters and what they're doing is they're bringing glucose from outside of the cell to the inside of the cell but they are bi-directional so they can move it out. One more thing I want to mention and I want to highlight this one. Glut 4. He's very very particular and the reason why I mentioned all these was particularly for this one. And why I want to say this is because GLUT4 is different from a lot of these other ones. These ones are generally insulin independent. In other words, they don't depend upon the concentration of insulin for their amount. This one though, GLUT4, is insulin. Dependent. What does that mean? That means when insulin is present, he can help to be able to increase the number of GLUT4 transporters or increase the efficiency of the GLUT4 transporters. Whereas GLUT1, GLUT2, GLUT3, they don't really depend upon the presence of insulin. They can function in bringing glucose into the cell, out of the cell, and they can regulate it based upon the presence of glucose, not by the presence of insulin. But again, that's a quick thing to remember. Okay, so now that we have all of our GLUT transporters and we know exactly how... This glucose is actually getting into the cell. Now we can move on. Okay, so we bring glucose into the cell through one of these glut transporters, depending upon the organ. Once we bring it in, we have to chain it. You know what I mean? Because remember what I told you, this is actually bidirectional. So at the same time, glucose could move out. To prevent this actual glucose from moving back out, we have to put something on it to prevent it from leaving. So what we do... is we put a special molecule on it. Look at this. So let's say that this is carbon number 1, 2, 3, 4, 5, 6. Okay? And on the 6 carbon I have a special thing coming off of it. Look at that. That right there is a phosphate. So what did I just put here? I put on here a PO4 3-group. Alright, that's our phosphate group. We put a phosphate on the 6th carbon of glucose. So what is it going to be called? This was glucose. There's a phosphate on the 6th carbon of glucose. This must be glucose 6, and I'm just going to put P, but you guys get the point. It's for phosphate. Okay, if I abbreviate some of these, I'll try to explain them. It's just easier to write them down in abbreviations sometimes. Okay. Now we got this glucose 6-phosphate. The question is, how the heck did that happen? How did I get this with no phosphate to a phosphate? There had to be some enzyme involved. Yes, there was. What is the name of that enzyme that's involved? This enzyme, it depends upon the tissue and we'll talk about it. There's two enzymes. One is going to be called hexokinase. One is specifically called hexokinase. The other one is going to be called... Glucokinase. Now we'll keep it the same color. The other one is going to be glucokinase. And what is the difference? Okay. Hexokinase is actually going to be present within the muscles or other different tissue cells. So many different tissue cells, but a lot of it is concentrated in the muscles. Technically they call this hexokinase type 2. Glucokinase is primarily in the liver. So let's actually put that here. So hexokinase can be in many different tissues like the muscle, it can be in a lot of different tissues, any different tissue in the body. But the liver is the only one that has glucokinase, but they also call it hexokinase 4. Just so that you guys know. Okay, so that was the first step, and this is what it's doing. It's involved in this step right here. These two enzymes, depending upon the tissue, are involved in the conversion of what? glucose into glucose 6-phosphate. Now the question is where did that phosphate come from? I'm glad you guys asked. It's coming from taking ATP and converting it into ADP. So what happened then? I had three phosphates, right? Because that's adenosine triphosphate. Then I went to adenosine diphosphate. That means I lost the phosphate. Where'd it go? Onto the 6-carbon glucose. Who is facilitating that? Hexokinase and glucokinase. Next step, we're going to go from this molecule now, right? We're going to go from glucose 6-phosphate to this guy right here. But now look at this. I'm still going to have the phosphate here, okay? That phosphate is still present. The only thing that's different is all I did is I switched a couple different molecules around a little bit. So I switched glucose and I switched its carbonyl form into different types. So all I did was I underwent isomerization. So in other words, glucose 6-phosphate and this other one right here, which is called fructose 6-phosphate, have the same number of carbons, same number of hydrogens, same number of octogens. Primarily, glucose is usually an aldehyde and fructose is usually the form of like a ketone. Okay, so these guys are just interconverting between like an aldehyde and a ketone. So they're just isomerizing. So this step right here, step number two, because this is step number one. Step number two is going to be catalyzed by a phosphohexose isomerase. Okay, so phosphohexose isomerase, because you know hexose just means six carbons, so it's a six carbon sugar right here. All of this enzyme is doing is converting glucose 6-phosphate into this other guy. What is this guy here called? This guy here is called fructose 6-phosphate. So again, what is he called? Glucose. 6, and I'm just going to put the P guys for phosphate. Okay, so that was the second step. Now we're going to go into the third step. We'll talk about this third step in great detail in the other video when we talk about regulation. But in this third step, it's a very important step. Just like this first step is a very, very important step. And you can tell the difference. Why can you tell the difference? This is a black arrow, this is a pink arrow. The pink arrows are reversible steps. So what does that mean? That means not only can I go from glucose 6-phosphate to fructose 6-phosphate, but I could go from fructose 6-phosphate to glucose 6-phosphate. But if I wanted to go from fructose 6-phosphate to this next molecule, that's possible. But I cannot go through that same pathway backwards. This step is not reversible by this enzyme that we're going to mention. They have to move through another enzyme. So this is an irreversible step, very regulated. Okay, so the enzyme involved in this step is going to be that of phospho- fructokinase 1. And like I said, I'm just going to abbreviate that PFK once, which stands for, again, phosphofructokinase type 1. It's involved in this step here. Okay, exactly how is it involved? What it's doing is, if you notice, I'm going to show you something here. This was the 6 carbon, this was the 1 carbon, right? And then you guys can do the math, 2, 3, 4, 5. On the 6 carbon, we still have that phosphate. Nothing has changed there. And now it's going to be on the 1 carbon. So now we have a phosphate on the 6 carbon, and we have a phosphate on the... Number one carbon. What must this molecule be called? Well, it has a phosphate on the sixth, it has a phosphate on the first. It should be called fructose 1,6-bisphosphate. Why do I call it bisphosphate? Because you've probably heard the term biphosphate and bisphosphate. Bisphosphate means that there's carbon spaces between it. Biphosphate means that they're right next to one another. Okay, so bisphospho means that the actual phosphate groups are actually separated. They're a couple of carbons away. Where biphospho means that they're right next to one another. Okay, but in this case it's bis. Okay, so what is this molecule called? Fructose 1,6- I'm going to put BP4, bisphosphate. Okay, what is the enzyme involved in that step? The PFK1, right? What happened? I had one phosphate originally on the six carbon. Then I added another one. Oh, I must have done the same thing that I did in this step here. Yep. So ATP gets involved in this step here and he loses a phosphate and gets converted into ADP. So I took ATP and converted into ADP. Okay, cool. So I lost and I actually used up an ATP in that step. Now look what happens here. I take this fructose 1,6-bisphosphate which is six carbons one, two, three, four, five, six and I split it in half to two three carbon fragments. Okay, but the phosphate on this Carbon right here should be on this carbon here. So now let's put a phosphate over here. Okay. And then that phosphate that's going to be over here, it should be right there. Alright, cool. And again, what is this guy right here? This is a phosphate. And again, what is this guy right here called? This is a phosphate. Okay, now that we've done that, what are these guys called? Now these ones are a little bit harder to name, okay? Unfortunately. I'm gonna give you guys a mnemonic at the end that will help you a little bit with that. But this guy right here is called dihydroxyacetonephosphate. Okay, so it's a three carbon molecule with a ketone in the middle and a phosphate on that carbon right there. Okay, we could technically call it the one carbon, but it wouldn't matter because on either side, you know, no matter how you name it nomenclature wise, it doesn't matter. So dihydroxyacetone phosphate. Okay, there's that guy. Now the thing is the hydroxyacetone phosphate isn't really utilized in this actual glycolysis pathway. He has to be converted into another molecule. What's this molecule here called? This one right here is different from this guy. This one is actually having an aldehyde on one end. So we call him glyceraldehyde. 3-phosphate. Okay? Sometimes you might even see it. Like, I'm actually going to denote this one as DHAP, dihydroxyacetone phosphate. And this one you're probably going to see in other videos as GA3P, glycerolide 3-phosphate. Okay? Now, here's the thing. What enzyme was involved in splitting this puppy? Okay. They called this enzyme involved in this step here. Right? Or we can even say if you want to involved in this step here. It's the same enzyme, it's just cleaving it. This enzyme is called aldolase. Here, let's actually do it like this instead. Let's just kind of encase it around this. So we'll circle this and this. He is involved in both of those steps. So he's actually doing what? He's cleaving fructose 1,6-bisphosphate into what? DHAP and GA3P. Now, like I told you, dihydroxyacetone phosphate doesn't really get in, it doesn't actually. should convert into this next glycolytic intermediate. He has to be converted into glycerolide 3-phosphate in order for him to be converted into this next intermediate. So we have to have an enzyme that is allowing for this interconversion between the two, or isomerization. That enzyme that is involved in this step is called a triose, because it's a 3-carbon molecule. Phosphate, I'm going to put P, isomerase. So it's called a triose phosphate isomerase enzyme and it's involved in the interconversion between GA3P and DHAP or DHAP to GA3P. Okay? Primarily with a little bit more of it going towards the GA3P depending upon the body's demands though. Alright, we'll talk about that in other videos. Now, glyceride high 3 phosphate, what happens to him? He is then gonna get converted into this next guy here. Okay, well this guy here has a phosphate on what carbon? So let's number this carbons here. One, two, three. Okay. Well that means that the phosphate is on the third carbon. That's why we named it that. Well then it should still have a phosphate here I would suppose, right? Let's see. Okay. It has a phosphate here. But oh would you look at that, there's another phosphate. Huh. So I added another phosphate. Okay. That's cool. Now what had to happen then? And what would we call this molecule here? We would actually call this molecule specifically. 1, 3. Now because the phosphates are actually having a space between them, this is bis. Bisphospho and then it's actually because it's a three carbon, glycerate. Okay, so it's called 1, 3-bisphosphoglycerate. That's this molecule here. Now there's a special enzyme involved in this step. It's a pretty cool enzyme. This enzyme is working right here in this step and I'm going to kind of abbreviate him also. He is called glyceraldehyde 3-phosphate, just like that. but dehydrogenase. Okay, this is an important step. Okay, a very important step here. What's going to happen is this enzyme, this glyceride 3-phosphate dehydrogenase, he's going to do two things. He's going to add two things into this reaction. One thing I'm going to do is I'm going to take NAD positives in this step. Okay, so I'm going to show it coming off of this reaction here. So look, I'm going to have NAD positive. He's going to react with that glyceride 3-phosphate in the presence of this enzyme. And what he's going to do is he's going to rip off hydrides off of the Ga3P. And when he does, he gets converted into NADH. What is hydrides? Hydride is just a fancy way of saying, here's my hydrogen, and then this hydrogen, it's going to have a proton, you know, within the center of it. And then what's going to be around it generally has just one electron. But in this case, a hydride has two electrons. So, what do we say a hydride is technically? We say a hydride is really a proton plus two electrons. That's what's going to be our hydride. And that's what this NAD molecule, this NAD plus is doing. It's picking up hydrides and using converted into NADH. Here's the tricky thing though. Look at this. You can really, really see this. This is fructose 1,6-bisphosphate. It gets converted into DHAP and GA3P. I told you most of this guy is getting shifted over here. So how many of him do I really actually have? I have two. Okay? I have two of him because I told you most of this is getting shunted over here. And then he's running through this reaction twice. So if that's happening twice then how many NADs am I actually producing? I'm actually producing two. I'm having two NADHs being made. Okay cool. That doesn't account for this phosphate. This enzyme is so tricky. He loves to just add in an inorganic phosphate. So you see here I'm gonna have an inorganic phosphate. I'm just gonna throw that into the reaction. So GA3P dehydrogenase is going to just throw a phosphate into the reaction and generate NADHs. Okay, cool. So we're good with that step. Now we're going to move on to the next step. Now look what happens here. You're going to notice something different. Oh. Did I draw a phosphate over here? No, I did not. What does that mean? That means that there's, I lost a phosphate somewhere. But again, what would we call this one? Okay, well, there's, it's going to have a similar name, but just get rid of the one. It's a three, but no biz, it's just a three phosphoglycerate. That's it. So what are we going to call this one? Three phosphoglycerate. Okay, that's the name of this substrate. So again, what is this one here called? Three phosphoglycerate. Now, in this step. There's a special enzyme involved here. This enzyme is really cool. And what he's doing is he's actually going to help to form, let's do this in a nice pink color here. I'm going to take ADP and convert it in this step to ATP. Okay? But because this reaction is happening twice, how many am I actually producing guys? Two. Okay? So I'm actually producing two ATP in this step right here. Okay. This enzyme is pretty cool. This enzyme right here that's working in this step is called phosphoglycerate kinase. Okay, so phosphoglycerate kinase is really, really special because what he's doing is, what is the definition of a kinase? We've talked about it when we talked about hexokinase and glucokinase, but kinase is by definition something that phosphorylates a substrate. Okay, well what is it phosphorylating? It's phosphorylating ADP. Where is it getting that phosphate from? The 1,3-BPG. It's ripping it off of the 1-carbon and giving it to ADP to make ATP. So that's what he is involved in. He is involved in this step here. Okay, good. We got our 2-ATP. Alright, that's cool. Okay, so now this 3-phosphoglycerate. Nothing crazy is going to happen in this next reaction. It's nothing us, not a really special... you know reaction nothing significant but look what happened to the phosphate all I did was I switched it I mutated it and I switched it from the third carbon to the second carbon because again we denote this one two three same thing here one two three so I switch it to the second carbon so what would you guys suppose this is gonna be this guy's name to phosphoglycerate nothing crazy on this one to phospho Okay, cool. Now the enzyme involved in this one is not really that important, but we'll mention it anyway just that you guys can have that. The enzyme involved in this step converting the 3-phosphoglycerate into the 2-phosphoglycerate is just called phosphoglycerate mutase. So phosphoglycerate mutase. Okay, that's that enzyme and he's stimulating this step. Okay, cool. Now the 2-phosphoglycerate is going to go to a kind of an interesting step. Okay, so what he's going to do is this phosphate is on the carbon here, right? So like let's say that here I have a 3-carbon structure, just for a second. I have a 3-carbon structure. And then what I have here is I have the phosphate coming off. What I'm going to do is I'm going to switch some structures around and I'm going to convert this into what's called an enol. And an enol is just when you have, according to organic chemistry, it's a double bond between these carbons with an alcohol coming off like that. That's an enol. But what I'm going to do is I'm going to put the phosphate on that now. Okay, so I'm going to have it kind of like switched off a little bit. So because I have this different kind of structure. What I'm now going to have is, is I'm going to have this phosphoenol, and it's a three carbon structure like this last one, pyruvate. So what is this last molecule here called? We call this molecule phosphoenolpyruvate. So this one here is called phosphoenolpyruvate. But I don't like that. I like PEP. Okay? It's easier to remember. Okay, but it's, you know, it's up to you. Alright, so PEP. And what am I doing? All I'm doing is I'm shifting it into a different kind of structure. So it's just making it a little bit more modified now. Okay, and then again, this is going to be my phosphate. So what do I call this? Phosphoenolpyruvate. The enzyme that's doing that is trying to convert it into an enol. So it's called an enolase. So what is the enzyme involved in this reaction here? The enzyme involved in this reaction is called an enolase. Okay. Nothing crazy. Really the more important steps in this process is the black lines one that I mentioned as well as this reaction here. Okay, last one. I'm taking the phosphoenolpyruvate and look what happens. No phosphates. That means that I must have formed ATP again. Yeah. So what did I do? That means I took two ADPs again, reacted them with this phosphoenolpyruvate and made two. ATPs. What does that mean guys? You should automatically your brain should start clicking kinase. It's got to be a kinase. That's what it is. It's a pyruvate kinase. So the enzyme involved in this step right here for glycolysis, this one here is called pyruvate kinase. And we're going to have a good discussion on him because he's highly regulated. Okay. And again, this step is not reversible. You can't go back through this enzyme. So pyruvate kinase is doing what? He is taking the phosphate from the phosphoenolpyruvate and converting it, right, into pyruvate by transferring that phosphate from the phosphoenolpyruvate onto the ADP to make ATP. But again, let's just quickly say something here. Why am I getting two? Because there's two glycerotohide 3 phosphates. There's two 1,3-bisphosphoglycerates. There's two 3-phosphoglycerates. There's two phosphoglycerates, there's two PEPs, or phosphoenolpyruvate, and there's going to be two of this last guy. What is this last guy here called? This last guy is called pyruvate, which is our three carbon molecule that we've been looking to get to by this endpoint, right? So now this is our two pyruvates. Okay, I'm liking it. Now, one other thing that we need to mention. What's the death, what's the actual fate of pyruvate? Because he can actually divert into two different pathways. One is he can actually come over here and he can get converted into this molecule. The other one is he can go over here and get converted into another molecule. Now since we're only talking about glycolysis, we're going to focus on what happens whenever we don't have oxygen and when we do have oxygen. So let's say that this pathway is occurring during anaerobic conditions. anaerobic conditions meaning no oxygen or very very little oxygen and over here this is going to be aerobic conditions meaning that you have oxygen there's plentiful amounts of it okay in a situation in which we don't have oxygen there's a sit there something bad happens I'm going to show you so you see these NADHs These NADHs are going to go and unload their hydrides onto specific molecules to take it to the electron transport chain and produce ATP. But whenever we don't have oxygen, these NADHs, they have no choice but to unload those hydrides onto somebody. Their last choice to unload the hydrides on is pyruvate. And what do they do? These NADHs, they come over here. And they say, I can't deliver this to the electron transport chain because I don't have anyone available to drop it off to. And what happens? He drops off those hydrides and gets converted into NAD positive. So he gets oxidized, but the pyruvate gets reduced and gains hydrides and gets converted into a molecule called lactic acid. And you know what's happening here? You know there's an enzyme, a really cool enzyme involved in this step here? Look at this guy here. Okay, it's got like six hairs on both sides. Soldiers are definitely retreating on this guy here. Okay, what is this guy doing here? This guy right here is involved in this reaction. What is this enzyme called? It's called lactate dehydrogenase. Why is this important? Okay, this one is important and the reason why is because lactate dehydrogenase is a reversible enzyme but it's basically converting pyruvate into lactic acid. What happens with this lactic acid? A couple different things can happen with it. It can actually go to the liver and be converted into glucose eventually. Or it can go to the liver and be used to make ATP. It all depends upon the body's demands. But what's the other dangerous thing about lactic acid? It's very acidic, so it's going to actually cause the pH to... Decrease. That was a heck of an arrow there. Sorry guys. This is actually going to cause the pH to decrease. It makes the blood more acidic. Now, one other thing is this has a lot of clinical correlation. What do I mean? So you see that lactate dehydrogenase enzyme? If you do a blood panel on somebody and you find that they have high lactate dehydrogenase levels, what does that mean? Okay. High lactate dehydrogenase, I know that he's converting a lot of pyruvate into a lot of lactic acid. Wait, doesn't that happen whenever there's no oxygen or it's very anaerobic? Yes. So what does that mean then? That means that this could be high in certain conditions in which you have maybe some type of MI, myocardial infarction. Maybe you have like a necrotic bowel. Maybe you have ischemia, whatever it might be. You could be having a lot of different situations where oxygen isn't being delivered to the tissues. And because of that, what's happening? You're not getting oxygen to the tissues and your LDH levels are rising because you have to convert a lot of that pyruvate to lactic acid. So you might have some metabolic acidosis also because lactic acid can actually decrease your pH and make it acidic. So you could actually might be seeing that in the anion gap. Okay, so now let's go ahead and like count up everything that we basically generated from glycolysis. So let's kind of tally up just a little bit of notes from this guys. So first off, we know that glycolysis is occurring where? I didn't really tell you where it's occurring in the cell. It's actually occurring in the cytoplasm. So all the fluid component of the cell. That's where it's occurring. Okay, so that's occurring in the cytoplasm of the cell. The next thing that we mentioned is what is our starting substrate? Our starting substrate is glucose. Okay, so we know that what? Glucose is our, I'm going to kind of abbreviate this here, it's our starting substrate. So I'm going to put SS, starting substrate. Then we know that this is occurring in the cytoplasm. What's our end product? So what's the end product? I'm going to put EP for end product. The end product is going to be two pyruvates. Okay, so I get two pyruvates out of this. That's an end product. What's some things that I produced which are byproducts of this whole glycolytic process? Well, I actually produced a total of a gross of 4 ATP. But, out of that, since I actually used... Two of the four of those ATP in the beginning step with the actual glucokinase and also again with the fossil fructokinase, I actually used two ATP, so really I only net how much? Two ATP net. Okay? Now the next thing. is with my NADHs. I actually generated a total of two NADHs in this process. So I generated two NADHs. And the last thing that I want to mention for this is that this is an anaerobic process, right? Generally, it's an anaerobic process. If we have no oxygen, it generates lactic acid. So generally, this process is usually anaerobic, meaning... Low or no oxygen. And then if that happens, then what can you generate? You generate lactic acid, okay, through fermentation processes. Okay, so in short, the skinny on it is that glycolysis is occurring where? It's occurring in the cytoplasm of the cell. Your starting substrate is glucose. Your end product is going to be two pyruvate molecules. What are you going to have? Grossing 4 ATP, but you used 2 out of the 4 ATP in this process, so you only really net 2 ATP. You generated 2 NADHs and it's an anaerobic process most of the time, meaning that there's very little oxygen and if there is very little oxygen, those NADHs unload onto the pyruvate and convert it into lactic acid. Okay guys, so in short, that's basically the glycolysis pathway. In the next video, you guys are going to see something because what we're going to do is, we didn't really talk about what happens when there's aerobic conditions. In aerobic situations, this pyruvate is going to get converted into another molecule, which we'll talk about, which is a two carbon molecule. And this two carbon molecule will have a special thing on it called a coag group. and this is called acetyl CoA and this is going to be called the transition step and that's what we will talk about in the next video when we go over the transition step reaction. Alright NGNerds I hope all this made sense I hope you guys enjoyed it I know it was a lot of information thanks for sticking in there with me if you guys liked it please hit the like button subscribe and put a comment down in the comment section. Alright NGNerds until next time.