okay moving forward with chapter seven cellular respiration and the next chapter chapter eight will be photosynthesis as mentioned before in a previous chapter cellular respiration and then photosynthesis are basically the same chemical formula except they're they're backwards so we're going to look at respiration first and this is how the body's going to extract the the energy from all the things that you you eat so we're gonna go from when that glucose enters the cell all the way down until it's fully broken down and we extract all the atp that we can now remember atp is the cell's currency this is what it's going to use for energy to make things for cell division like we've already covered and so this is where all that energy is going to take um this is where it's going to come from and then again everything even like muscle contractions when you're walking down the street this is where it's coming from from glucose and remember the body can also utilize other things so we could use proteins we can use nucleic acids we can use fats in basically the same thing to extract the atp except we're going to focus on glucose and so by definition glucose or cellular respiration is the release of energy from molecules such as glucose remembering there can be other molecules involved and then we're going to synthesize atp molecules for cellular work or forced metabolism respiration is aerobic aerobic meaning it has to have oxygen to operate efficiently so this is why actually we breathe in and then it gives off co2 this is why we breathe back out is just to get that oxygen down to the cellular level it is a coupled reaction and again we've covered this in the previous chapter meaning that one reaction takes place driving the other reaction at the same time so we're going to make a little bit of atp actually we're going to make about 36 to 38 per glucose molecule if it's efficient and at the same time we're going to take glucose which has carbon hydrogen and oxygen in it break down these bonds in the presence of oxygen get carbon dioxide and water as byproducts but we're going to get a lot of atp out of that and so let's start that journey and so glucose is a high energy molecule again all of those bonds between the carbons the hydrogens the oxygens that's what respiration does it's going to break those high energy bonds and then it's going to extract some of that energy to make atp one glucose molecule if it's efficient we get about 36 atp molecules out of it and so the pathways within cellular respiration is used as a way to take that glucose molecule apart and slowly release that energy for atp synthesis there are a couple enzymes involved we have nad plus and fad each one of these is actually going to carry the energy or portions of the energy in those bonds down to the end step of cellular respiration and so again we have nad plus fad each one of these is going to carry two electrons and two hydrogen atoms we're going to see how those play into the last step of respiration and then they're going to pick up those electrons as specific enzymatic reactions and carry these electrons to the instep called the electron transport chain and it is in the electron transport chain where we're going to make most of the atp so let's look at that reaction again where we're going to pick up those hydrogens we're going to pick up the electrons again this is a reduction oxidation reaction we've covered this again in the previous chapter and so one of these has to happen along with the other so both of these are happening at the same time and so our enzyme comes in in ad plus it's going to pick up a couple hydrogens is going to get a couple electrons it's going to join that into a new enzyme called nadh plus hydrogen proton that we're going to see is going to go to the electron transport chain where it's going to give up the electrons it's going to give up those hydrogens and then eventually the end result will be atp and then some waste products now remember about enzymes they get recycled and that's true of this one as well it's just going to go right back into the cycle we're going to turn it right back into nad plus complete the reaction again and this is a nice cyclic reaction so there are four primary phases of cellular respiration phase one glycolysis this is where we're going to split glucose lysis means to break apart after we do that there's a preparatory reaction getting those molecules ready to enter the citric acid cycle citric acid cycle we're going to harvest some more electrons we're going to get some more hydrogens and then all of those are going to go down eventually to the electron transport chain and this is where we're going to make most of our atp so let's start with that first step and again glycolysis is the breakdown of glucose into two smaller molecules called pyruvate first we're going to oxidize it by the removal of the electrons and the hydrogen ions remember an ion has a charge to it and then these are going to provide energy writing glycolysis to make two atp so we're going to get a little bit energy just from that initial breaking up of glucose after that we move into the preparatory reaction we're going to take pyruvate which is the glucose after it's been broken down we're going to oxidize it again we're going to get it into the form called acetyl coa and then we're actually going to remove a carbon dioxide so this is where some of the waste products is starting to come from and so we're going to take one three carbon molecule the pyruvate and we're going to turn that into a two carbon molecule the acetyl coa the prop reaction occurs twice because in glycolysis glycolysis remember we're going to get two pyruvics that's the first step in glycolysis we're going to take that six carbon sugar and we're going to break it down into two pyruvates our next step after that is the citric acid cycle this is cyclic meaning it's going to constantly turn and then the things that are turning in this cycle are going to be used over and over again the acetyl-coa is converted to citric acid as it enters the cycle now the citric acid cycle has to turn twice because again remember we spit with split glucose and so we're going to have two of those acetylclase entering so we've got to take two turns before we can fully change glucose into the next products at the end we have the electron transport chain so this is where we're going to take electrons we're going to take those protons the hydrogen ions essentially what we're going to do is we're going to extract the energy in the electrons we're going to pump hydrogens across the membrane i'll show you that in a graphic and then eventually we're going to make atp from the energy transfer and again under aerobic conditions again this is with oxygen we get anywhere from 32 to 34 atps in this step remember we already got two atps from glycolysis and so as those electrons enter the electron transport chain they're at a high energy state so they have some energy to give off in the electron transport chain there are proteins that are going to accept the electron extract a little bit of energy for atp production the electron is going to be passed on to another protein get a little more energy another protein more energy another protein a little more energy for atp and then eventually this electron has given up all it can and we're going to see right at the end it's going to be converted back to water our second byproduct of cellular respiration so we've talked about glycolysis glycolysis happens in the cytoplasm of the cell so this is where we're going to break down that glucose after the cell has taken it in preparatory reaction is going to happen as it moves into the mitochondrion that product is then going to enter the citric acid cycle which happens in the matrix or the center of the mitochondrion and then the final step in that box this is the electron transport train and this is going to happen in the folds called cristae inside of that mitochondrion this is we're going to take all of these electrons that are coming in from glycolysis from the preparatory reaction or the citric acid cycle they're all feeding into the electron transport chain and then we're going to make atp from that glycolysis we do get two atps we're going to get a couple in the citric acid cycle but then we're going to get a total um of 32 maybe 34 depending on how efficient inside of the electron transport chain now pyruvate is the product of glycolysis and even if there's no oxygen available even if it's anaerobic and anaerobic means without oxygen we can still break down glucose but unfortunately it's not very efficient and so what we're going to get after we break it down is we're going to form something called lactate in our muscles and in our cells or also fermentation as it's called can produce alcohol so this is ethyl alcoholic we have wine and beer and then carbon dioxide is a result and it is fermentation but also that we use in baking the baking of bread undergoes the fermentation process that's why bread essentially rises especially when it gives off carbon dioxide so back to glycolysis again this is the breakdown of glucose into two molecules of pyruvate essentially we're just snipping like glucose in half again this takes place in the cytoplasm of the cell this step doesn't require oxygen we're not going to need oxygen until we get into the mitochondrion but it does transform that six carbon sugar or that six carbon molecule into two three carbon molecules of pyruvate glycolysis does take a little bit energy to get it started we have to sniff those bonds and so we're going to use up two molecules of atp just to get things going a little bit further in the energy harvesting steps we're going to oxidize that three carbon molecule and then we're actually going to take the electron and we're going to take a hydrogen and we're going to form nadh and then that does go down to the end step that's going to go down to the electron transport chain through the process we're also going to make some atps in total we're going to make four of those and this is done by something called substrate level phosphorylation so this is going to happen in the presence of an enzyme and then we're going to add that phosphate to the adatd then we're eventually going to get four atps from that so we've used two to get things going we're gonna make four and so the net out of glycolysis is going to be two atps so here's an example of substrate level atp synthesis so again it does take an enzyme we're going to add a phosphate to an adp and then we are going to get atp so again glycolysis takes glucose pyruvate and then that's going to feed into the next reaction and then at the same time we're getting electrons we're getting hydrogens carried by the nadh to the electron transport chain so the inputs the outputs of glycolysis this is what i really want you to get out of this portion of the chapter in a minute i'm going to go into a lot of detail each step of glycolysis but i want you to know what goes in the inputs and i want you to know eventually what comes out and so the inputs we have that six carbon glucose molecule and again this comes from our food the cell's taking it in it wants to break it down we have our first enzyme we have nad plus this is going to carry the hydrogen we're going to use up two atps and remember this is what we need to get this reaction started and then we're also going to bring in four adp's plus four phosphates this eventually is going to produce some atps from us now when glycolysis said and done the outputs are two three carbon pyruvates because we've taken this we've clipped it in half we've taken some hydrogen so we're going to make two nadhs so two hydrogens we used up two atps we're making two adps but we're also making four atps from the four adps that we brought in so the net gain is two atps and we're getting pyruvate and we're getting hydrogen ions and electrons so again let's look at this step by step but again what i really want you to get out of this lecture is that previous slide the inputs the outputs okay step one glucose glucose comes into the cell and again this is bringing the nutrients that we've gotten from the digestive system so this could be from your breakfast your lunch or snack whatever but first thing we have to do is take two atps and we're gonna break this down we're gonna weaken this center bond so eventually we can break this in half step two as a result this glucose which has six carbons indicated by these six gray spheres gets broken down so now we have three intermediate molecules called g3p step 3 nad plus comes in also another phosphate comes in and then in this step we're going to pick up an electron we're going to pick up a hydrogen ion and then we're going to weakly bond that phosphate to the end of that 3 carbon sugar this is again another intermediate called p g this is still our three carbon sugar step four we're gonna take uh we're gonna remove a high energy phosphate from the bpg by two adps and then we're going to produce our first atps and then we're going to get back our three carbon molecules with one phosphate and so this is where we're going to make a little bit of energy here step five we're gonna oxidize two of those three pgs by removal of water and so we're actually gonna form water here this is metabolic water so this is water taking out when we break those bonds this is hydrolysis hydrolysis and what we're going to get again are is water and then two pep molecules six we're going to move the high energy phosphate from two peps by two adp and we're going to get two more atps and then eventually we come to the end of glycolysis and we get our two molecules of pyruvate and these essentially are now just the carbons because we've taken these phosphates off and we've turned these in to atps once again on that previous slide that i mentioned we spent a little bit of time on i just want you to know the inputs and the outputs i don't necessarily need you to know all of these intermediate steps in between just know the process of how glucose comes in takes energy we're going to make some atps along the way we're going to harvest some electrons we're going to harvest some hydrogen ions and at the end result are two pyruvates that eventually are going to enter the mitochondria and remember this step happens in the cytoplasm of the cell so back to fermentation so in cases where we don't have enough oxygen we again can utilize the anaerobic pathway remember anaerobic is without oxygen and this is fermentation so in animal cells pyruvate from glycolysis accepts two hydrogen ions and two electrons and reduced to a waste product called lactate now for using yeast this is going to generate ethyl alcohol in co2 by fermentation and as i mentioned before the alcohol is ethyl alcohol this is what we find in wines and spirits and then the co2 is a gas given off and that gas is what makes bread rise and then we have two nadhs these are going to pass electrons to pyruvate and then again it's going to reduce it to lactate it's not very efficient but we can get some energy out of glucose when there's not a lot of oxygen and so in humans when we need it it's important so we can get an additional store of atp and so if we have to run and we're working out really vigorously your muscles are going to do fermentation because we can't bring in enough oxygen through the respiratory system but over time that lactate is going to build up in your muscles and your cells don't like it it's actually toxic to the cells if it builds up too much this is why your muscles start to burn this is why they get sore eventually over time that cells in your and your muscles can metabolize it and then we can get rid of it but you can't accumulate too much lactate your muscles just won't go for it but for short bursts this is a good way for us to get that extra energy through atp production so again fermentation yields only two atps these two atps represent a very small amount of the potential energy stored in that glucose molecule remember potential energy is in bonds or the chemical structure of that glucose molecule what we really want to do with this is cellular respiration we want the oxygen interacting so we can be really efficient again get that 36 get that 38 through the entire process of respiration so again let's just look at the output and inputs and outputs of fermentation we have our glucose we still have to spend two atps and we're also still going to add those four adp's plus a couple phosphates outputs we get lactate again short-term energy not a problem but we can't do it for a long time in other organisms fermentation leads to alcohol and co2 we're going to get the two adps when we use the two atps to get things started overall we're going to get to 4 atps but it's only a net gain of 2 atp so again not very efficient it's not like the 36 that we can get from complete glycolysis in cellular respiration here's that pathway again lots of details in here but essentially the same thing i want you to know what comes in glucose energy we're going to make pyruvate we're going to get rid of some co2 and then we're going to get some atp but unfortunately in animals we're going to make lactate or in plants and yeast we're going to make alcohols and co2 so after glycolysis if you remember we're going in next to the preparatory reaction and this is as that pyruvate is entering the mitochondrion and so the punch line here is we want to change pyruvate into another molecule that's going to enter the next step the citric acid cycle this does happen in the cristae the mitochondria and so this is the inner folds we get our pyruvate in we're going to convert it into a two carbon acetyl group that's going to enter the citric acid cycle now the preparatory reaction does again start or produce acetyl coa so this is what this represents carbon dioxide is produced again that is a waste product hydrogen atoms are removed from pyruvate and that are picked up again to form nadh plus another hydrogen and again the electrons that are picked up the hydrogens that are picked up these are all going to the electron transport chain and we have to do this twice because remember we get two products per glucose because the initial step was to cut that glucose molecule in half into the citric acid cycle we go and again this is a cyclic pathway where the acetyl-coa is going to enter and then eventually we're going to continue to break down all the bonds between those carbons and any hydrogens that are left we're going to strip those off too so at the start the two carbon acetyl group of acetyl coa is going to combine with a four carbon molecule already in the cycle when it joins we get a six carbon molecule called citrate which gives the citric acid cycle its name and then the co-a is recycled back into the preparatory reaction to start all over so each of those two carbon acetyl groups is oxidized to two co2 molecules through those reactions we're going to make three nadhs plus a proton or a hydrogen ion again these are going to the last step then we're going to make one fadh2 again two more hydrogens again this is again an enzyme that we talked about in the beginning of this chapter in addition one atp is produced by substrate level atp synthesis remember this requires that enzyme and this is everything we're going to do here in this cycle this cycle has to turn twice for the original glucose molecule because remember that first step we snipped it in half we get two from one glucose right here's that important slide again i want you to know the inputs i want you to know the outputs inputs two acetyl groups six nad pluses two fads and then two adps plus two phosphates the cycle goes around and i'm to show you that in detail in a minute and what we get out of that is carbon dioxide again a waste product we're going to get six nadh plus another hydrogen proton again going to the electron transport chain we're going to get two fadhs going to the instep and we're actually going to generate two more atps that the body can use okay so the citric acid cycle again takes place in the matrix the matrix is the fluid center of the mitochondria we're going to make a couple atps out of the citric acid cycle we're going to harvest some electrons we're going to make some nadh and we're going to make some fadh2 all again feeding into that electron transport chain so now let's go through the citric acid cycle step by step step one c2 acetyl group combines with the c4 molecule already inside of the cycle and it will be recycled this is to be kind of become that six carbon molecule so we're coming in from below we have that c4 we're going to grab these two carbons and then we're going to have a six carbon molecule continuing that cycle this is citrate step two nad plus is going to come in reaction is going to take place where we're going to harvest some electrons we're going to grab some hydrogens and because we've snipped one of these bonds down to get the electrons to get those hydrogens we're going to make co2 this is going to leave through the respiratory system step three nad plus is going to come back in we're snipping another bond so we pick up some more hydrogens we produce another co2 in addition to this we actually get in step four we get an atp produced as well step five our second enzyme fad is gonna come in harvest some more hydrogens and then now this c4 is going to go around and actually be recycled but before it does we still have some more hydrogens to pick up and so we're going to bring in another nad plus grab a couple more of those hydrogens and then again all of this is going down to the electron transport chain again this is going to happen in the citric acid cycle which is in the matrix two atps electrons hydrogen ions and then co2 are the products now our last stop the electron transport chain this is located in the cristae of the mitochondria and again the cristae are the inner folds of membranes and it's across this membrane that we're going to take the energy in the electrons we're going to use those hydrogen protons and then we're going to make atp from that so high energy electrons are going to enter the system and then after the electron transport chain takes the energy low electrons are going to leave the system as water coming in we have two electrons per nadh plus a hydrogen and then fadh are going to enter the electron transport chain each of these are reduced and then oxidized to give up their hydrogens and electrons so as those electrons pass from one carrier to another energy is going to be captured and stored as a hydrogen ion concentration we're actually going to inside of the mitochondria concentrate hydrogen on one side of the cristae now oxygen is going to combine with hydrogen ions to form water and then nad plus and fad are recycled to pick up more electrons from glycolysis the prep reaction and then the citric acid cycle remember these are enzymes and enzymes are going to be used over and over so once again we have the electrons and hydrogens coming in from not only glycolysis but the preparatory reaction the citric acid cycle all feeding in to the electron transport chain and eventually we're going to get anywhere from 32 to 34 additional atps so here's a really detailed kind of graphic of what's going on this is the cristae this membrane inside of the mitochondria so this is a bilipid layer each of these orange structures represents a different protein now to start the nadhs and the fadhs are going to come in they're going to give up their electrons so this is now a high energy electron this is our first step it's going to transfer that energy to this protein and this protein is going to use that energy to take hydrogens inside of the matrix and pump them to the outside of the other side of the membrane effectively concentrating them on this side fadh is going to come in we're going to release some more hydrogens inside the electron is going to move forward to the next protein give up some energy so we can take these hydrogens again pump them and concentrate them on the other side electron moves forward next protein gives up some energy we take the hydrogens inside of the matrix pump them to the outside of that membrane again concentrating all of these hydrogens inside of the inner membrane space of the mitochondria now this electron is given up all it can and so now it's going to combine with an oxygen it's going to combine with a couple hydrogens and we're going to get water from that that's our second waste product remember co2 is a waste product and then water this is where the water comes from now we have all of these hydrogens on the outside of this membrane they're concentrated inside of the matrix we have very few hydrogens and so what we know about diffusion is things are going to move from high concentration to low concentration in this case they're actually going to move through another protein called atp synthase complex and as these hydrogens pass through this protein they're going to give up just enough energy to take an adp plus a phosphate change that into atp this is where the energy comes from this is where these hydrogens are flowing back into the matrix to form atp and then that atp can come right back out and serve the needs of the cell now this flow is known as kidney osmosis chemiosmosis is chemical osmosis remember we talked about osmosis and volume involving water water moving from high concentration to low concentration but in this case we're taking these hydrogen protons from high concentration through atp synthase making atp and again a currency that the cell can use so chemiosmosis is chemical osmosis and this is how your cell makes atp so again first electron carriers are located in the cristae of the mitochondria that's the inner membrane the nadh is going to pass electrons to the first acceptor of the electron transport chain these electrons are at high energy those electrons are going to pass along a series of electron carriers each time they're going to give up a little bit energy and they're going to pump hydrogen ions into the inter intermembrane sprays concentrating them into that space so this is going to lead to something called a proton gradient also in that membrane the cristae have atp synthase and because now the hydrogen ions are in concentration they're going to flow back into the matrix by the atp synthase complex and then as the hydrogen passes into the complex it's going to give up enough energy to take adp and form atp and again this is chemiosmosis or the flow of those hydrogen ions back into the matrix to make atp so mitochondrion this is the outer membrane inner membrane space your membrane sprays are where those hydrogens are going to be concentrated cristae is all of this membrane material that essentially electron transport chain is going to take place and then the matrix is the innermost portion so again those hydrogen protons get pumped to this side they flow back into the matrix and we make atp so again one more time nadh it's going to deliver that high energy electron it's going to transfer that energy to the proteins in the electron transport chain their job is to pump hydrogen ions into concentration space those are then going to flow back through atp synthase produce atp and then the atp can be used in the cell and this particular process is known as kimmy osmosis or the flow all right so here's the yield so the energy yield for one glucose again you're first gonna get a total of four tts atps by substrate level atp synthetic and remember this is where we're using an enzyme to build atp by attaching it directly to a dp you get two in glycolysis and you get two from the citric acid cycle now the electron transport chain will get anywhere from 32 to 34 again depending on how efficient and this process is known as chemiosmosis so chemiosmosis takes place in the electron transport chain substrate level atp synthase takes place in glycolysis in the citric acid cycle as well so again just another chart to help summarize what we've been talking about in this chapter in glycolysis you take glucose you make two atps you get two pyruvates all in well we're going to enter the mitochondrion with the two acetyl coas we're going to enter the citric acid cycle we're going to make some co2 we're going to make six nadh and additional protons we're going to make two fadh we're going to make four more carbon dioxides and we're also going to net two atps now all of these products are going to feed into the electron transport chain so everything that happened to glycolysis everything that happened in the citric acid cycle goes into this final chain where eventually we're going to take in the presence of oxygen we're going to use that oxygen up we're going to make water and then eventually we're going to get about 32 or 34 just from the electron transport chain we add that to what we got in the citric acid cycle and glycolysis and so we're going to get 36 to 38 again depending on how efficient so the difference in energy content of reactants and products can vary and again i want you to remember that glucose is what we used here today but basically the same thing is going to happen with proteins same thing's going to happen with lipids something's going to happen with nucleic acids i don't necessarily worry about these particular numbers i don't want you to know that but what i do want you to know is about 36 atp are produced in respiration and remember from a previous chapter that when we convert energy we're always going to lose something and so even if cellular respiration is very efficient we're only getting about 39 to 40 percent of the actual energy per glucose the rest of this up to about 60 percent is going to be lost as heat or metabolic heat and a lot of that's lost to your skin but it's also a good portion of the heat that keeps us warm so that is respiration