so what I want to do in this video is give ourselves an overview of cellular respiration and it can be a pretty involved process and even the way I'm going to do it as messy as it looks it's going to be cleaner than actually what goes on inside of your cells and other organism cells because I'm going to show clearly from going from glucose and then see how we can produce ATP through glycolysis and the kreb cycle and oxidative phosphorilation but in reality all sorts of molecules can jump in at different parts of the chain and then jump out at different parts of the chain to go along other Pathways but I'll show kind of the traditional the traditional narrative so we're going to start off with for this narrative we're going to start off with glucose we have a six carbon chain right over here and we have the process of glycolysis which is occurring in the cytool the cytool of our cell so if this is the cell right over here you can imagine well the glycolysis the glycolysis could be occurring right over there and that process of of glycolysis is essentially splitting up this six carbon glucose molecule into two three carbon molecules and these three these three carbon molecules we go into detail into another in another video we call these pyruvate pyate and in the process of doing so and this is I guess you could say the point of glycolysis we're able to on a net basis produce two atps we actually produce four but we have to use two so on a net basis we produce two atps and I'm going to keep a little table here to keep track so we produce two atps and we are also we're also in the process of that we reduce two NAD molecules to nadh remember reduction is gaining of electrons and you see over here this is positively charged this is neutrally charged it essentially gains a hydride so this is reduction reduction and if we go all the way through the pathway all the way to oxidated phosphorilation the electron transport chain these nadh's these these the the reduced form of NAD they can be then oxidized to provide and in doing so more energy is provided to provide to produce even more atps but we'll get to that so you're also going to get two nadhs two nadh's get produced now at that point you could kind of think of it is a little bit of a decision point if there's no Oxygen around or if you're the type of organism that doesn't want to continue for some reason with cellular respiration or doesn't know how this prvate can be used for fermentation and we have videos on fermentation lactic acid fermentation alcohol fermentation and fermentation is all about using the pyruvates to oxidize your nadh back into NAD so it could be reused again for glycolysis so even though the nadh has energy that could be eventually converted to ATP and even though the pyruvates have energy that could eventually be converted into ATP when you do fermentation you kind of give up on that and you just view them as waste projects and you use the pyruvate to convert the nadh back into NAD D and then glyco can occur glycolysis can occur again but let's assume we're not going to go down the the fermentation pathway and we're going to continue with traditional aerobic cellular respiration using oxygen well the next thing that's going to happen is that the carboxy group and everything I'm going to show now it's going to happen for each of these pyruvates so you can imagine these things all happening twice so I'm going to multiply a bunch of things times two but what happens in the next step is this carboxy group this carboxy group is stripped off off of the pyruvate and it essentially is going to be released as carbon dioxide so this is our carbon dioxide being released here and then the rest of our pyruvate which is essentially an acetal group that latches on to coenzyme a and you'll hear a lot about co-enzyme a sometimes they'll write just you know COA like this sometimes they'll do COA and then the sulfur connect bonded to the hydrogen and the reason why they'll draw the sulfur part is because the sulfur is what bonds with the acetal group right over here but what so you have the carbon dioxide being released and then the acetal group The acetal group bonding with that sulfur and by doing that you form acetal COA and acetal COA just so you know you only see three letters here but this is actually a fairly involved molecule this is actually a picture of aetl COA I know it's really small but hopefully you appreciate that it's a more involved molecule that the acetal group that we're talking about is just this part right over here and it's a co-enzyme it's it's really acting to to transfer that acetal group and we'll see that in a second but it's also fun to look at these molecules because once again we see these patterns over and over again in biology or biochemistry acetal COA you have an Adine right over here it's hard to see but you have a ribos and you also have two phosphate groups so this end of the acetyl COA is essentially is essentially an ADP but it's used as a co-enzyme everything that I'm talking about this is all going to be facilitated by enzymes and the enzymes will have we'll have co-actors co-enzymes if we're talking about organic co-actors that are going to help facilitate things along and as we see the cedal group joins on to the co-enzyme a forming acetal COA but that's just a temporary attachment that the the acetal COA is essentially going to transfer the acetyl group over to and now we're going to enter into into the citric acid cycle it's going to transfer these two carbons over to oxal acetic acid to form citric acid so it's going to trans these two carbons to this 1 2 3 four carbon molecule to form a 1 2 3 4 five six carbon molecule but before we go into the depths of the citric acid cycle I want to make sure that I don't lose track of my accounting because even that that step right over here where we decarbox the pyruvate we went from pyruvate to acetal COA that also reduced some NAD to nadh now this is going to happen once for each pyruvate but we're going to all the counting we're going to say is for one glucose molecule so that for one glucose molecule is going to happen for each of the pyruvates so this is going to be times this is going to be times two so we're going to produce two na two NAD DHS in this step going from pyate to acetal COA now the bulk of I guess you could say the the catabolism of the carbons or or the things that are eventually going to produce our our atps are going to happen in what we call the citric acid or the kreb cycle it's called the citric acid cycle because when we transferred the acetyl group from the co-enzyme a to the aalo acetic acid we formed citric acid and citric acid this is the thing that you have in lemons or orange juice it is it is this molecule right over here and the citric acid cycle and it's also called the creb cycle when you first learn it seems very very complex and some could argue that it it is quite complex but I'm just going to give you an overview of of what's going on the citric acid once again six carbon it keeps getting broken down through multiple steps and I'm really not showing all of the detail here all the way back to oxal acetic acid where then it can accept and it can accept the two carbons again and just to be clear once the two carbons are released by The co-enzyme a then it can that coenzyme a can be used again to decarbox some pyruvate so there's a bunch of Cycles going on but the important takeaway is as we go through the citric acid cycle as we go from one intermediary to the next we keep reducing NAD NAD to nadh in fact we do this three times for each cycle of the citric acid cycle but remember we're going to do this for each for each acetyl COA for each pyruvate so all of this stuff is going to happen twice so for we're going to go through it twice for each original glucose molecule so here we have one two three nadhs being produced but since we're going to go through it twice and we're going to do accounting for the original glucose molecu we could say that we have six na 6 n dh's six or you could say six nads get reduced to nadh now you also in the process as you're breaking down going from going from the six carbon molecule to a four carbon molecule you're releasing carbon as carbon dioxide and you also have traditionally GDP being converted to G GTP or sometimes ATP converted to ATP but functionally it's equivalent to ATP either way so we could also say that we're going to directly remember we're going to do all of this stuff twice so we could say that two two I'll just say two atps to make it simple we could say GTP but I'll say two atps because once again this happens once in each cycle but we're going to do two cycles for each glucose and then we have this other co-enzyme right over here fad that gets reduced to fadh2 but that stays coal attached to the enzymes that are facilitating it So eventually that's being that's that's being used to reduce to reduce co-enzyme Q to qh2 so I'm just going to write the qh2 here but once again you're going to get two of these so two two Q 2 qh 2 Q H2S now let's think about what the net product over here is going to be and to think about it we should we should just we we'll just and and I I'll do a little bit of a Shand we'll go into more detail in future videos is these co-enzymes the the nadh the the the qh2 these are going to be oxidized during oxidated phosphorilation or and the electron transport chain to create a proton gradient across the inner membrane of mitochondria we're going to go into much more detail in the future but the that proton gradient is going to be used to produce more ATP and one way to think about it is each nadh each nadh is going to produce and I've seen a count it depends on the efficiency and where the nadh is actually going to be produced but it's going to produce anywhere between two and three atps the each Q each of the each of the reduced co-enzyme Q's so the qh2 that's going to each produce about one and a half atps and people are still getting a good handle on exact L how this is happening it depends on the efficiency of the cell and what the cell is actually trying to do so using these using these ranges actually I'll say one and a half to two one and a half to two atps and these are these are approximate numbers so let's think about let's think about what our total accounting is so if we just count up the ATP or the gtps we're going to get two there two there so we're going to have four direct or very close to direct atps net being created and then how many nadh's we have 2 4 and then we add six we have 10 nadh's 10 Na dh's and then we have two of The co-enzyme Q's two Q H2S so that's going to be four atps this is going to be between this is going to be between 20 and 30 and adhs uh sorry 20 to 30 atps 20 to 30 atps and then this is going to be 3 to Four 3 to four atps so if you add them all together if you add the low ends of the range you get let's see 20 + 3 plus 4 that's 27 atps 27 atps and the high end of the range let's see you have 4 + 30 plus 4 you have 38 38 atps and 38 atps is currently considered to be kind of the theoretical maximum but when we actually observe things in cells it looks like it comes out at around 29 to 30 atps and this once again it depends what the cell's trying to do the type of cells and the type of efficiency but all of this is happening through cellular respiration and just to get a better sense of where all of this is occurring where all this is occurring we said glycolysis is occurring in the cytool the citric acid cycle this is occurring in the in the Matrix of the mitochondria so this space right over here that is the citric acid cycle in that little magenta space that I've drawn so that's the Matrix in the video on mitochondria we go into much more detail on that and then the actual conversion of these co-enzymes of you know the electron transport chain that's occurring across the membrane of the Christa and the Christa are these folds FR these kind of inner membrane folds of our mitochondria so it's occurring across that across those the membranes of those of of these of actually the the plural is Christy Christa is a is the singular of the Christ Tha and we'll go into more detail into that in other videos