hello everybody this is a quick video on the beginnings of cellular respiration namely the parts about glycolysis and the intermediate step there's a second part of the video which we'll be looking at the citric acid cycle and oxidative phosphorylation let's go ahead and get started on the first parts right here so i believe we've already talked about this in class where we would like to look at the summary reaction equation where we have first of all we have the two reactants here along with the three arrows that represent the major stages that cellular respiration is is made up of and the two products carbon dioxide and water so when we look at this i like to analyze this diagram to see how this all fits in here and we're going to take a look at this overview a number of times so that way we can see which part is which now notice first of all we're talking about this we have the mitochondrion mitochondrion you notice it's ion not mitochondria that's the singular for of mitochondria mitochondria is pleural so we have multiple mitochondria in our cells but in this case we're going to focus on one of them so that's why it says mitochondrion and then outside of that of course is the cytoplasm and we can see from this diagram that we've got it simplified our first step is called glycolysis you can see the blue the blue matching each other and then this kind of peachy orange color representing the citric acid cycle and the third main part is oxidative phosphorylation so we're going to take a look at each part first of all you can see that glycolysis its function is to break down glucose into pyruvate that's what we're going to be looking at first and as a result of that we get some energy out of this this is all happening in the cytoplasm and then also as a result of glycolysis we get to make a little bit of nadh nadh you remember is an electron carrier and in this case it is the reduced form because it has gained two electrons in there and of course an h the oxidized form is called nad plus so this one has gained it and you can see we're going to keep those electrons to do something with it later on then from breaking about part pyruvate we can see that pyruvate is going to move into the mitochondrion and during that process we're going to give off a little bit of co2 this is the co2 that you and i breathe out of our lungs when we exhale then in the citric acid cycle that's in the mitochondrion we can see it's a cycle so things will be reformed again but we can see that in the process we're going to form a little bit of atp and of course we're also going to form some carbon dioxide probably more importantly still though however it's gathering up those electrons and you can see that nadh and fadh2 are bringing those electrons in from the citric acid cycle into oxidative phosphorylation so that's our third step is called oxidative phosphorylation and oxidative probably sounds familiar to you with thinking about the word oxidation oxidation as you know no has to do something with electrons in this case we've we learned about losing electrons so that's the first part you can see it says electron transport so something about electrons gonna happen and then the second half of the name is phosphorylation which as you know already phosphorylation means adding on a phosphate group onto something in the end of this we can see there's something called chemiosmosis which sounds really familiar too because we learned about osmosis which is the movement of water across a semi-permeable membrane from an area of high concentration to an area of low concentration in this case though it's not osmosis it's chemiosmosis so we'll figure out what that means later on but you can see in any case that really there's the big bang for the buck at the end of oxidative phosphorylation where we get a large amount of atp so now let's take a look at the very first two parts of glycolysis and this part in between which currently has no name all right so we're going to work on glycolysis remember glycolysis is breaking down glucose and it we're ultimately going to get it into pyruvate we're going to make a little bit of atp and we're also going to make some electrons be taken over with an electron carrier okay so here's an overview you can see glucose here it's not really like you've seen before it's represented in an entirely different fashion in that you can see it has the carbons that's what's represented here one two three four five six in glucose c6h12o6 there's the six carbons you can't see the rest of it though they've decided to simplify it in our textbook so we can kind of keep our eye on what's happening otherwise the diagrams get fairly complicated so we have glucose here that gets broken down into two pyruvate and it kind of makes sense when this happens because if you're talking about breaking then we're going to be breaking a bond here right so it looks like the bond being broken is is probably here right and what holds together in the bond what's what's involved in a bond are electrons so we get these two three carbon parts here that get broken apart where the electrons go well we can see over here that we have nad plus which is that electron carrier which would like to have two electrons sitting in it so we end up getting those electrons and putting them in here so what happened to nad plus to become nadh nad plus gained two electrons and a hydrogen and that means when we say gaining we call that a reduction so so far we have a reduction that's occurred the gaining of electrons from nad plus to become nadh those electrons came from somewhere though we already said that they came from glucose so glucose is the one that lost it so here we've lost electrons and we call that of course an oxidation okay so currently we've got an oxidation reduction reaction which is not surprising they always come together as couples right if you can figure out what's happening with one you can figure out what's happening with the other so in this overview we can also see that adp plus p together yields 2 atp we're going to see how that happens the process of going through glycolysis is not just one step it turns out that remember that any time that you have energy conversion or a reaction you're going to be losing heat and so in order to do this if we did this in one jump like we're talking about right now there would be a whole lot of heat lost and that would mean that our cell would just boil up so we're going to do this in a lot of little steps so this is just the overview notice in the next screen we're going to see glucose as six carbons drawn at the top okay so here are the six carbons of glucose and the first thing that we can see is that atp becomes adp well where did that third phosphate go can you see it well hopefully you've noticed that that third phosphate went right on this end of the glucose so now it's named something different glucose 6-phosphate so we've really energized this molecule we've had to use a little bit of energy to get things going that's why it's called the energy investment or preparatory phase next thing that happens here is we can see really for all intents and purposes these look the same so in terms of this this is glucose 6-phosphate and this is fructose-6-phosphate well if you remember both of them are c6h12o6 so we call them isomers of each other they have all the same parts so since they are isomers and we're going between them what's happened here is we've got an isomerization that's what's happening between glucose 6-phosphate and fructose 6-phosphate they've been isomerized okay so now we have fructose 6-phosphate and we're going to see that hey atp is going to be losing one of its phosphates again to become adp and here's where it went it went on the other side of the fructose so notice it's called fructose 1 6 diphosphate clearly what i don't want you to memorize all these names that's really not the most important part and also what would be important to know in a general sense but not memorizing is that each one of these steps that's shown here is mediated by an enzyme it's catalyzed by an enzyme so um if you are a biology major and in the future you take your next biology class you would learn all of these molecules here and then you would learn all the enzymes that were involved but you can guarantee that their names are going to be really similar to what it is that they're making or what they're breaking apart so in any case don't memorize them i'm only using them so that way i can refer to them in our diagram so you know what i'm talking about okay so we've really highly energized the glucose molecule to make it this molecule now now next thing we're going to see in the next picture is that we have the same molecule this is all the same first part that you saw but now what we're going to do is split this in half so we're going to break this uh fructose 1 6 diphosphate into two pieces and now we refer to this as g3p or glyceraldehyde 3-phosphate in any case g3p will do so we've broken this up well that means that we lost the electrons where did they go on the nad plus to become nadh so nad plus to nadh we can see that's a reduction again it's happening twice because it's happening with what's going on between these and this is the oxidation going from g3p to 1 3 diphosphoglycerate so these are two different molecules that have been broken apart um and been really energized by some phosphates that have come from the solution that is in the cell in the cytoplasm there's all kinds of phosphates and hydrogens and all kinds of molecules floating around in the cytoplasm so here we end up adding it to the other end well now we've highly energized this three carbon molecule which was called g3p before and that's going to be really beneficial to us okay well take that little molecule that we had at the end there and notice it has the two phosphates at the end this is an organic molecule right and what's going to happen is we're going to take off one of the phosphates and add it onto adp to make atp so first of all my question for you is what kind of molecule is this one here well if you recognize that they use purple in our book or also that it's it's catalyzing something you can see that it's an enzyme so this enzyme right here is assisting by removing the phosphate off of the organic molecule and putting it onto adp to make atp so we refer to this as substrate level phosphorylation because the substrate is where they're getting the phosphate from this is the substrate that fits into the active site as you know okay so you see this picture at the bottom of the screen here um there they are the three carbons with the two phosphates on either side of it okay and then we're going to bring those in the next picture to the top so it's the same thing from the bottom just brought up to the top here they are okay so we have the same three carbons with the two phosphates and we can see adp now becomes atp what does that mean that means that adp has become phosphorylated where did it get it from from the 1-3 diphosphoglycerate same thing is happening on the other side now at this point we're just basically moving around the phosphate in terms of location now i know these all look the same from here to here but there has also been a movable removal of water okay and so at the bottom now it's energy energetically in place to take off the last phosphate from pep as it's called and add it onto the adp to make atp and so at the end we're left with two pyruvate which should look pretty familiar since that's what we were talking about earlier today that glucose would be split into two pyruvates so that's glycolysis remember i said many steps so that it doesn't burn up the cell so this is the whole thing altogether none of it should be overwhelming because you know what all these parts are for example going back to the last slide if we take a look and we say that star we know that's atp if we see the blue oval we know that that's water if we see the brown rectangle or its cousin i guess it's the white one with the brown edge around it that's going to be our electron carrier so that's nadh or nad plus so again it should all look really familiar now notice here at the beginning as i mentioned there's going to be this energy investment right so we invested two atps here and then down at the bottom we can see that the cell earned uh four atps so gross towards atps but you know ain't nothing in life is free is it and so that's the same thing here this is kind of like a job in that well you go to work to make some money in this case we're going to say money is energy right and you make some money but of course you have to take the bus there and the bus home or take your car there and car home and that's going to cost gasoline that's this investment you're going to pay for the gasoline in advance and then hopefully you're going to make more money than you lost on the gasoline so this is energy investment and then this is payoff so what we say like with making a paycheck in a job what we'll say is that if you have atp in this case we grossed it right we it we grossed for atp okay and we ended up using two we put this little space here we ended up using two of them so that means in the end overall we ended up getting to atp net that's how much we brought home essentially so in this overall deal we got to make a little bit of energy out of it we made 2 atp all right so that is looking at glucose glycolysis in detail let's take a look at it and kind of review it again but this time what i'd like you to do is take a moment pause this recording and write down what are the reactants and what are the products you should be able to do that from this diagram so what are the reactants and what are the products okay so go ahead and pause now and then i'll pick it back up in a moment good okay so what are the reactants well the main reactant we know is going to be glucose we can usually call the main reactant is the one involved with the carbon that we're all involved with so that's a reactant and then what is it being broken down into two pyruvate right we've got two pyruvate on there then at the same time we're making adp plus p into 2 atp so that's our other reactants and products but probably more importantly we've noticed before is that we're taking 2 nad plus and we're going to yield two nadhs plus two h pluses okay as i said you should be able to do this from the diagram this little table is not the most important thing it's being able to look at the diagram and see what's going on because it'll tell you the whole story if you read it correctly okay good so there's glycolysis right now we're going to continue on and we're going to look at one other little part now so that is glycolysis at the end we have pyruvate and we're going to take that pyruvate and move it into the mitochondrion okay so this is called the intermediate step just so you're aware that they call it lots of different names um and so intermediate step was a name that they've been using for a long time but also call it grooming like hair grooming or taking care of yourself they'll also call it a couple other things too so just be aware of that that term okay so we can see the intermediate step is actually going to be happening somewhere where it we got pyruvate in the cytoplasm and then somehow it's transported into the mitochondrion so it can go into the citric acid cycle we're also going to give off a little co2 okay so here is the intermediate step activity what i suggest is that at the moment you go through that it is in your study guide and see if you can answer those questions please attempt to do that first i think it'll be beneficial for you to work through it and then afterwards come back and we'll follow this discussion of it so you can go ahead and pause now and then when you come back then you can start it up again and we'll continue with discussing intermediate step okay so now that you've done the intermediate step we're going to take a look at this this should look pretty familiar here's pyruvate right where did the pyruvate come from well if you recall it came from the glucose in glycolysis so we broke it in half at that time so we have pyruvate here okay and it looks like the first thing that's going to happen is we're going to lose carbon dioxide so carbon dioxide is taken off one of the carbons is goes away and then we're going to add on coenzyme a to make acetyl co a acetyl coa is a molecule that only has two carbons and it has this coenzyme attached so what's the the deal with coenzyme a coenzyme a is a really important part to enable this former pyruvate to get inside of mitochondria so let me give you an analogy you know in your sunglasses or your regular glasses how you have that little teeny screw right there and when it comes out it drives you crazy you try to use your fingernail you try to use a dime you try to use all these tools but really what it comes down to is you need that teeny teeny tiny screwdriver right well coenzyme a is like the teeny teeny screwdriver so what it's going to do is help that acetyl coa to move in or that acetyl group to move into the mitochondria can't do without it all right at the same time what's going to happen is nad plus becomes nadh well what kind of equation is this what kind of reaction is this going from nad plus to nadh well hopefully you'll remember this that look we're gaining electrons so if you gain electrons that means what we have here is a reduction and so if that's reduced what's oxidized well you know that they're coupled so at some point we're going to have to say if it's not this that's oxidized it must be this so here is where we're going to lose electrons and of course that's called an oxidation now that makes a whole lot of sense if you think about it because what we had here was a situation where another bond was broken right between these two carbons this carbon and its oxygens went out as carbon dioxide and the remainder is left as acetyl coa which then attached to coenzyme a so we had an oxidation reduction reaction okay next thing i'd like you to do is think about this all of this is multiplied by two why well if you remember glucose broke in half to become two pyruvate so when we do some accounting like last time figuring out the reactants and products what we really need to do is multiply everything by two so let's figure out what are the reactants and what are the products go ahead and do that put this on pause and see if you can figure it out okay so now that you're ready with that let's check to see how you did so in terms of the reactants we had two pyruvates remember we're multiplying everything times two and that yields two of the carbon dioxides and two of the acetyl coas you could potentially use two coenzyme a on the reactant side if you'd like it's alternatively written both ways all right now reactants we can see there's two nad pluses and then it yields two nadhs plus their two h's all right so that was looking at the intermediate step and glycolysis and now you're ready for part two which is now that we're in the mitochondrion let's figure out what happens in the citric cycle okay so thank you for joining me right now if you'd like to watch the next one it's the next one in the zoom module recordings if you are not seeing it live with your class okay have a good one bye you