Glycolysis Made Easy!

hi everyone Dr Mike here in this video we're taking a look at glycolysis [Music] now the analogy I like to use for glycolysis is taking a car stripping out of its parts to be utilized Elsewhere for something better that's pretty much what we do for glucose we ingest carbohydrates in our food we ultimately through our digestive system produce glucose and we strip the glucose of electrons so that we can give it to our mitochondria so that we can produce ATP this is the energy currency of the body so to begin we need to look first at glucose and exactly what it is remember glucose as a chemical is C6 h12o6 so there's six carbons 12 hydrogens and six oxygens the main thing we want to look at here are the carbons and I'll tell you when we start playing around with the other components so let's draw it up as a six carbon molecule one two three four five and six and let's label them so we're going to go from one to six one two three four five six so here are the six carbons now when we ingest this glucose we're obviously going to be ingesting it and it's going to be in our bloodstream now we need to get it from our bloodstream into the cells of our body now let's focus on the liver because the liver is going to be the primary site of glycolysis so they go from the bloodstream into the liver it needs to move through certain Transporters the thing is that the liver is obviously made up of liver cells hepatocytes that just like every other cell in the body has a phospholipid bilayer molecules that have a slight charge associated with them can't freely move through or molecules that are too big the thing with glucose is that actually has a slight charge associated with it and it's a little bit too big at the same time so it can't freely move into the liver cell it needs a transporter to do so and these Transporters are called glut now there's actually four major types of glucose Transporters and they're located in many different tissues of the body so what type of glucose transporter are we going to use for the liver let's take a quick look at these glucose Transporters because they are important for us to understand particularly when it comes to taking a look Clinic so the first thing you need to know is there's a mnemonic for you to remember for these glucose Transporters this mnemonic is big fat bullies kick small little pansies producing nervous kids and mad fathers how's that for a mnemonic it's a big one isn't it big fat bullies kick small little pansies producing nervous kids and mad fathers just like any good mnemonic you take the first letter of each of these words and that tells you where you're going to find it but first let's just separate it out like this one two three and four these are going to be our glut one glucose one Transporters these are going to be glut 2 glucose two glut 3 and glut 4. so where can you find each of these types of transport as well first here the b stands for blood F stands for fetus and the b stands for blood brain barrier so glucose one Transporters are located in these particular areas glucose two kidneys small intestines liver and pancreas glucose three receptors placenta neurons and kidneys again so why is kidneys what do the kidneys have do two different types of glucose Transporters because there's a multitude of cell types in the kidneys so they have different types of glucose Transporters and then finally glut4 is muscle and fat so when I say fat I'm obviously talking about adipose tissue in like really importantly you know that you need insulin for glucose to enter cells right we always say insulin is the key to open the doors to the cell to let glucose in so that we can strip glucose of those electrons to give to the cell to make ATP to make energy right so how do we do this well have a look insulin is not really needed for glucose one you don't need insulin in order for glucose to enter these cells you don't need insulin for glucose 2 transport is you don't actually need insulin for glucose three Transporters but you do need insulin full glut for now you might be thinking but we're always told that we need insulin very true but let's have a look many of these tissues are quite small volume lines taking up the percentage of the body small amount but muscle and fat takes up a significant percentage of our body mass and therefore they require insulin which means if you don't have insulin most of the glucose that's floating through your bloodstream will not be pulled into your muscle and pulled into your fat and will be locked in the bloodstream and can damage the tissues of your body so insulin is really important because huge amounts of glucose will be pulled into muscle and pulled into fat that's an important point right let's now take a look let's go back to glucose and have a look at what's going on in glycolysis and what is the whole purpose of us going through the process of glycolysis so at the end of the day the whole purpose of this glucose is for us to be able to rearrange it and strip electrons off so that we can hand it to the mitochondria so it can produce ATP and energy so what you're going to find is we're going to rearrange this molecule and this is the process of glycolysis so in order for this glucose to get out of the bloodstream and move into the liver cells it needs to move through a glut 2 transporter because we told you that right it's a glut to transporter and so this glucose moves through and now it's in the hepatocyte the liver cell now what we want to do is make sure that this glucose molecule does not leave the liver cell we want it to remain inside we don't want it to go back out so what we do is we phosphorylate it now remember ATP adenosine triphosphate here's a phosphate molecule and here's another phosphate molecule and here's a third phosphate molecule adenosine triphosphate these are phosphates what we want to do is snap off one of these phosphates from ATP leaving ADP and we're going to put it on so here's the thing let's count these one two three one two three four five six so what we've got here is we're going to snap on one of these phosphates onto the sixth carbon beautiful what do you think we're left with what is this thing called this is going to be called glucose six phosphate so that's unsurprising so let's name this glucose six phosphate so we've now undertaken the first step going from glucose to glucose 6-phosphate it's not reversible the whole reason of putting the phosphate on is so it doesn't escape the cell again that's the purpose of it okay wonderful now what do we need to do well we need to talk about the enzyme that did this so the enzyme that does this is actually called hexo kinase or gluco Karnes think about this hexamine six six carbon atoms beautiful kinase is telling you it's playing around with giving or taking a phosphate group and glucose is glucose now why is one or the other why they're two they're hexokinase is in the liver that's the enzyme that the liver uses in this first step glucokinase is elsewhere obviously we're in the liver here so we're going to talk about hexokinos in this first step in order to get this phosphate I told you we took it from ATP so we needed to take ATP we needed to strip it of one of its phosphates and now we've left with a DP this is really important to highlight your body does not like using ATP if it doesn't have to it wants to conserve it or make it the fact that it's deciding to waste energy in the process of glycolysis tells you how important glycolysis is to your well-being and survival so now we've gone through the first step we've created glucose 6-phosphate what we want to do is rearrange some of these carbons to produce another molecule so we're going to rearrange some of these carbons and this is a reversible step so we're still going to have once we rearrange them we've simply rearranged them in a different order but you've still got number one to number six it's just different carbons so we're still going to have the phosphate on the sixth carbon but we'll simply rearranged glucose 6-phosphate into something now called fructose six phosphate so the point I'm trying to get across with this step is that glucose 6-phosphate fructose-6-phosphate are identical except the carbons have been swapped around a little bit what that's telling you is that glucose as a molecule is C6H12O6 fructose as a molecule is also C6H12O6 except it's just rearranged a little bit but it still has six carbons 12 hydrogens six oxygens fructose is taken from fruit glucose can be taken from other carbohydrate-based sources like Breads and pastas and so forth so now we've got this now in order to do this just rearranging the carbons required an enzyme called an isomerase I sum arrays and so it's called a phospho-hexo isomerase or phospho hexo isomerase or elsewhere phosphogluco isomerase all right so we'll get the phospho hexos isomerase all right that's changing from glucose 6-phosphate to fructose six phosphate what's the next step from fructose 6-phosphate again we can it's an era a step that doesn't go backwards right so we went from step one to step two it's not reversible step two to step three it is reversible from here to here it's irreversible again and the reason why is because we're adding another phosphate to it this time we're adding it to number one number one and number six so one two three four five six let's show the phosphate at the sixth point right here and now we're adding a phosphate at number one po4 three negatives so adding a phosphate here which means we've now gone from fructose six phosphate to fructose one six bis phosphate fructose 1 6 biz phosphate this is important right because by means two and there's two phosphates here bees is telling you that there's two but they're not next to each other that's pretty much it now to do this we needed to do what we did here take ATP pull a phosphate off so we're going to have ATP pull a phosphate off to produce aedp and that means we're going to be using a kinase as well what's the kinase here it's going to be called phosphofructose kinase phospho fructose kinase all right we've now just wasted or I should say spent because I don't think it's wasted two ATP molecules in so far we've produced fructose 1 6 bisphosphate adding this second phosphate makes it a step that can't go backwards but it also makes this an unstable molecule and in making it unstable what it does is it allows for it to be able to split into two so what it's actually splitting into is one's going to have the six phosphate one's going to have the one phosphate so let's have a look in actual fact once it's split that's not going to be six it's going to be three so you can have one two three and you can have one two three so what we're going to do is we're going to take this top one to make it easier and we're going to bring it down the bottom here so we've got this molecule with the phosphate on the first this is going to be called dihydroxy acetone phosphate dye hydroxy acetone phosphate and then this one which is going to have it on the third this is going to be called glyceraldehyde three phosphide glycerol the hide three phosphate now the enzyme that did this process is called elderlase wonderful and it's reversible and these two can exchange or change with one another predominantly it's dihydroxyacetone phosphate is going to turn into glyceraldehyde 3-phosphate and it does this through an isomerase right so it's going to be a triose phosphate isomerase that's the enzyme that allows for it to go from dihydroxacetone phosphate to glyceraldehyde 3-phosphate what's the next step the next step is going to take this glyceraldehyde 3-phosphate and it's going to add another phosphate but it's not going to do it like we've done it here so it's not going to use a kinase so let's take a look let's draw this up we're going to go from here to here it's a reversible step and what we're going to do is we're going to have that that there's our three one two three carbons we're going to have the phosphate down here and we're going to have a phosphate up here now importantly because fructose 1 6 bisphosphate has split off into two and this one moves up into this one we actually end up having two glyceraldehyde 3-phosphate which means when we move over to produce this which is called 1 3 bisphosphoglycerate this is called one three this phospho glycerate it's a big word isn't it one three bisphosphoglycerate we have how many of them we have two of them this is really important we have two of them how did we get that phosphate and what else has happened let's have a look importantly What's Happening Here is this we are taking an NAD plus this is a really important for glycolysis and we are turning it into n a d h what does this mean this is now the first step from for us stealing electrons from glucose how does this work let's take a look let's get rid of this ATP molecule and look at NAD Plus so NAD plus what it actually does is it steals from the glyceraldehyde 3-phosphate it's stealing hydrogen now remember what hydrogen is hydrogen is the first atom on the periodic table hydrogen as a neutral atom with no charge overall is composed of one proton in the middle and one electron flying around the outside the electron and the proton balance each other out so it's a neutral atom what NAD plus does is it steals a hydrogen from glyceraldehyde 3-phosphate now if it does this right if NAD plus is stealing a hydrogen you're going to get n a d h plus still they're still a positive because you've taken a neutral molecule here right a neutral atom but we see here that it doesn't have the plus so how do we get rid of that positive well we need to steal an extra negative so what nod plus does is it doesn't just steal one hydrogen it steals two hydrogens but what it does remember this second one is going to have exactly the same thing but what it does is it steals the electron from that hydrogen and then throws away the positive charge so what we get here is the NAD plus steals two hydrogen one of which it's both the positive and the negative the other one it's just the negative just the electron and then it's left with a positive hydrogen ion so at the end of the day NAD plus steals two hydrogen one of which it takes with it and the other which it steals just the electron and throws the positive proton away hopefully that makes sense so what we've got here is NAD plus turns to nadh plus a proton but remember two here so there's going to be two here so we're actually taking two NAD plus and turning into two nadh and two hydrogen ions remember in this process it's stealing two electrons but what it's producing are hydrogen ions what is the definition of an acidic solution something that has a lot of hydrogen ions the process of glycolysis releases hydrogen ions it can make the microenvironment slightly acidic that's important all right so now I've produced this but you're probably thinking where's this extra phosphate come from good question we throw two Foss inorganic phosphates into the process what is the enzyme we use in this process it's not a kinase it's a dehydrogenase because we're stealing hydrogen dehydrogenate the molecule so it's an A's it's an enzyme so it's going to be called glyceraldehyde 3-phosphate dehydrogenase where can we write that let's put it here glyceraldehyde so it's going to be this written glyceraldehyde 3 phosphate dehydrogenase that's the enzyme that we use in this step so now we've got two of these one three bisphospho glycerates what do we now do with it well strangely we try and get rid of the phosphate on the first carbon how do we do that again a reversible step where we one two three we've thrown off that phosphate we've got the phosphate on the third still how did we get rid of it hmm let's have a think maybe what we can do is take some of the ADP that we've produced and turn it back into ATP but remember we've got two of these molecules so we're actually taking two ADP and creating two ATP we're creating energy through glycolysis now what's this molecule called well it's no longer one three bisphosphoglycerate it's going to be called three phosphoglycerate let's write this down three phospho glycerate what's the enzyme that does this process it's going to be called phosphoglycerate kinase so we've now got three phosphoglycerate what we want to do is put that phosphate from the third to the second so we've got one two three let's now add this phosphate group here it's now added to the second so now we've got two phosphoglycerate two phospho glycerate it was a rearrangement a very strange one so it's a mutate so it's phosphoglycerate mutase phospho glycerate mutase and remember we've got two of them I've got two of these we've got two of these next step is what we're going to do is we're going to turn this two phosphoglycerate into an enol so phospho enol pyruvate what does that mean if we turn this into a phosphoenol pyruvate it means what we do is we take the carbon the carbon the carbon right one two three we add an oxygen group to number two and then add the phosphate onto that oxygen group and create a double bond here from the second carbon to the third all the rest have been single carbon bonds this is called an enol so it's now phospho enol pyruvate phosphoenol pyruvate and the enzyme we use is called enolase enolase all right we're nearly at the last step now the last step not nearly we are at the last step the last step is a non-reversible or irreversible step going from phosphate or pyruvate to pyruvate and so to do this again like I said it's non-reversible so let's go down like this and what we do is we take that phosphate off and we go from phosphenol pyruvate to pyruvate so how do we do this let's now we've got this one two three carbon molecule that remains remember we've got two of them now so we've got two phosphenol pyruvate we've now left with final product You could argue of glycolysis being pyruvate some would argue that the final product might be lactate but that's another conversation and phosphenol pyruvate two pyruvate it gets rid of that phosphate how does it get rid of the phosphate let's bring the ADP back in to steal some so we're going to have ADP coming in turning it to ATP there's two of them two of them stealing that away this is going to be pyruvate kinase let's take a look and there we go what have we ended up with I'm going to get out the road so that you can see this board really nicely starting from glucose we used up ATP we then added a phosphate group and then rearranged the molecule then we used up more ATP so that we could split the molecule apart which ultimately created two molecules of glyceraldehyde 3-phosphate here we started to utilize the ability to steal hydrogen and electrons going from NAD plus to nadh I'm going to talk about this in a second then we created more ATP then flipping it around turning it into an enol we created more ATP again so we created two NAD plus nadh plus molecules we created four ATP and we're left with a pyruvate in actual fact we're left with two pyruvate so what do we do with this pyruvate that's an interesting point this pyruvate can turn into something called lactate now pyruvate can go down the process of acetyl Calais which jumps into the Krebs cycle that's going to be in another video to help us create more nadh and fadh2 or it can go down another Pathway to create lactate now creating lactate takes this nadh and the hydrogen ions that were produced in this step and reverses them back into NAD plus going from pyruvate to lactate think about what I said here this process of glycolysis releases hydrogen ions so it's a little bit it makes the environment slightly acidic that's really important but if you turn pyruvate into lactate and often this happens when we do a lot of a lot of anaerobic so no oxygen based exercise going to the gym you lift heaps of Weights really quickly where you do 100 meter sprint and you're trying to produce more ATP than oxygen that you have present then we often produce lactate not lactic acid there's no evidence that the body actually produces lactic acid but it produces this lactate and it's not because it's necessarily an alternate fuel source which it can be but because it mops up excess hydrogen ions muscles can get sold due to too much acid and if the lactate mops up these hydrogen ions it helps produce a better environment for the muscles so that they can keep Contracting important so this is the process of glycolysis I hope that it was helpful hi everyone Dr Mike here if you enjoyed this video please hit like And subscribe we've got hundreds of others just like this if you want to contact us please do so on social media we are on Instagram Twitter and Tick Tock at Dr Mike tadarovich at d-r-m-i-k-e-t-o-d-o-r-o-v-i-c speak to you soon foreign [Music]

Channel: Dr Matt & Dr Mike

Views: 171,443

Keywords: glycolysis, glucose, pyruvate, made easy, glut, transporters, metabolism, biochemistry, health, college, lecture, university, biology, biochem, how to, understand, make sense, easy, simple, why, nad+, nadh, electrons, purpose, dr mike

Id: TnQGcKpahfM

Length: 28min 12sec (1692 seconds)

Published: Fri Mar 17 2023