Biology in Focus Chapter 7: Cellular Respiration and Fermentation

hey guys today we're gonna be talking about chapter 7 from Campbell biology and focus and this is going to be over cellular respiration so we kind of skip this and went ahead to photosynthesis but now we're going back to chapter 7 so we've already talked about photosynthesis and all of those reactions now we're going to talk about cellular respiration because this occurs in all organisms so I put this picture in here I added this into the presentation to give you an overall image of what we're gonna be talking about today so there's three main stages of the process of cellular respiration if we're talking about aerobic cellular respiration there is a glycolysis there's the citric acid cycle and then the electron transport chain those are the three big steps this is a really good picture I need you to come back to and whenever you don't understand something or you need the overall image I also really like that it's telling you like the investment stage versus the payout stage so you can see our net gain overall okay so I need you to come back to this picture throughout if you're confused about the overall process and I also need you to come back here after you're done listening to make sure that you can explain these steps because then you know you know it for your test okay so we know all about energy from ecology freshman year biology okay but we know that energy flows into an ecosystem from the sunlight that's our solar energy and we know that the sunlight now that we just talked about photosynthesis goes into the leaves of our plants it goes into the chloroplast excites the electrons we have the plant making chemical energy out of this solar energy so we have a transfer of energy from solar to chemical all the time everywhere the process is identical if you remember your rap song okay so photosynthesis in this process is going to generate oxygen and oxygen and organic molecules organic molecules like glucose remember that organic molecules just means that it contains carbon to hydrogen bonds c6h12o6 definitely fits that bill okay so these are going to be used as fuel for cellular respiration it's a cyclical relationship and that's the very last slide of this presentation then I also added in for you photosynthesis and cellular respiration definitely rely on each other a hundred percent one cannot exist without the other okay so basically we already talked about photosynthesis and how it's going to make oxygen and organic molecules called glucose and now we're going to combine those two things in order to enter into the cellular respiration process so our cells are going to use this chemical energy that's stored in organic molecules like glucose in order to generate ATP which powers work so ATP is kind of like a currency of our cells you know that the mitochondria is the powerhouse of the cell if you learn anything about biology ever in your life that's probably the thing that you remember the most it's kind of become like this awful joke right so this is where we're going to be focusing today all of our energy in the cell literally because it's generating ATP so we're gonna be talking a lot about the mitochondria today we're gonna be talking about how to create ATP that's the whole point a cellular respiration like why do you need to do it because you need ATP why because it's energy without energy you're dead that's how it works okay so previously when we talked about photosynthesis photosynthesis is an anabolic reaction which means it's a building up reaction to think about anabolic like anabolic steroids I like to pick things up and put things down we're talking a lot bodybuilders making big muscles catabolic is exactly the opposite so instead of making glucose now we're going to be breaking glucose and here's how I like to remember it catabolic cats I don't like cats I have dogs you know because they bark in every one of my videos catabolic cats cats have claws claws can tear things apart catabolic cats have claws to tear things apart okay so this is a breakdown this is a breakdown of organic molecules like glucose and it's an exergonic reaction which means it's going to be releasing heat or energy okay so there's two main types are going to talk about and it's kind of reiterated in the next few slides but fermentation is one of the types which is just a partial breakdown of the sugar and it occurs in the absence of oxygen so if there's no oxygen present fermentation okay and then aerobic respiration aerobic refers to oxygen so this is going to consume organic molecules and oxygen so combine them together in order to create ATP which is a much more efficient process so anaerobic respiration and aerobic respiration are similar in that they both consume compounds other than oxygen so like I said there two main parts you have either aerobic or anaerobic so aerobic is again referring to oxygen so this occurs in the presence of oxygen it's a much more efficient process whereas anaerobic occurs without oxygen and it's kind of like a last resort for like us as humans but other organisms like rely on or anaerobic respiration like that's all that they do and that's just that's how their their little cell bodies are created right okay so we eat things carbs lipids proteins we eat these things there's three different classes okay yes the fourth classes nucleic acids but we don't think about that like a like a macro molecule for us that we're consuming right so carbohydrates fats proteins you consume all of them they all give you fuel right it's not like oh if you eat a stick of butter you're not gonna get any fuel I mean it's just a different kind of fuel than if you were eating a doughnut which contains a lot of carbohydrates but we're always going to talk about glucose going through this process just because it's the most fluid coming from cellular respiration I'm sorry from photosynthesis into cellular respiration glucose is just like the ideal molecule to follow because it doesn't quote break any of the rules and it goes through the complete cycle of cellular respiration instead of getting to like skip steps which if you consume fats and proteins you don't start in the same place in the cycle it's a cycle like a circle you just enter at different points in that circle the same process happens but I don't want to start off telling you maybe about like a protein that gets to skip a couple of steps because then you don't learn those steps so that's why we always talk about sugar glucose right but do you eat other things yes do they give you fuel yes we just talk about glucose because it goes through the entire process and it's coming fresh out of photosynthesis so this reaction is happening in plants so as soon as the plants make this glucose well it's just like your neighbor handing you a cup of sugar great thanks Linda now what do I do with it in order to get energy you got to break it down right so the plant has glucose great now you gotta break it down you spend all that time building it up now you gotta break it right so cellular respiration is really cool because it happens in every single organism whether it's aerobic respiration or Ana respiration but like I said that's why we use glucose yes you get fuel from other sources but this is just the one that goes through the entire system and like I said it's coming straight out of photosynthesis we just talked about this so it's gonna make better sense this way so redox reactions kind of drive this whole process and we talked about that with photosynthesis as well so when we're talking about redox reactions we're talking about oxidation and reduction happening together it's like coupled reactions okay so it's a transfer of electrons during our chemical reactions that release energy stored in organic molecules like glucose because that's what we're talking about right so this release energy is ultimately used to create our ATP that's the whole point of cellular respiration if that's like they give up like the takeaway that you get from all of this then you learn something cellular respiration is used to make ATP period that's what it's used for why do we need it to make ATP without ATP you're dead okay so redox reactions like I said there are coupled reactions its chemical reactions those are gonna transfer electrons between reactants and they're called oxidation reduction reactions or short redox reactions now remember I gave you a little acronym oil-rig oxidation is loss reduction is gain so this is what it means so in oxidation you have a substance that's losing electrons oxidation is loss oil o IL oxidation is loss okay these things are oxidized okay in reduction are IG oil-rig this is the r IG part reduction is gain a substance gains electrons so if you just remember oil-rig it'll help you remember which is which okay so in reduction is substance gains electrons or is reduced so the amount of positive charge is reduced so here we have an example of a redox reaction okay so you have na that becomes na plus because it is losing electrons because it's becoming more positive you know that it's oxidized sedation is loss remember electrons are negatively charged so something gains a positive charge it had to be losing electrons and the opposite is true for our RCL like it's a CL minus here so this is reduced because it's gaining electrons remember electrons are negative so because we throw on that negative sign there that minus sign we know that it's actually gaining electrons and again that's oil-rig to help you remember all of that here's another example if you have a minus and it goes away you've got to be getting rid of electrons because you're becoming more positive that's oxidized the opposite is true on the other end here if you're adding a negative then you know you're gaining electrons because electrons are negative okay so the electron donor the thing giving up electrons is called the reducing agent and the electron acceptor the thing that's taking on some of the electrons is called the oxidizing agent and that goes back to our acronym oil-rig make sure that you can differentiate between those so some redox reactions do not transfer electrons but change the electron sharing and covalent bonds remember that covalent bonds are how electrons kind of create like a little bridge between our atoms in order to share electrons to complete their valence electron cloud right an example of this would be methane and oxygen so here's kind of what this looks like so we have our methane is our reducing agent our oxygen which remember occurs as a molecule it's our oxidizing agent makes sense because it's oxygen it's like they did that on purpose right so we have our methane that's becoming oxidized it's literally gaming oxygen okay and then we have our oxygen that's becoming reduced because it's gaining electrons in the form of hydrogen and you can see all of the chemical equations or all of our little dot structures spelled out at the bottom of the screen for you okay so our redox reactions that move electrons closer to electronegative atoms like Sojin release chemical energy that can be put into to work right so um anytime that you're releasing energy like heat it can be used to do work okay so oxidation of our organic fuel molecules during respiration remember I said that photosynthesis is generating our oxygen and it's generating glucose now we're going to take these organic molecules called glucose and we're going to mix them with oxygen in order to oxidize them and we're gonna be breaking them down okay so during cellular respiration the fuel glucose cuz that's the ideal fuel is oxidized and oxygen is reduced these redox reactions are going to be very important that you understand what they mean remember oil rig okay so organic molecules with an abundance of hydrogen like carbohydrates and fats are excellent fuels because they have a whole lot of this hydrogen that we can use to to you know reduce things and as hydrogen with its electrons is transferred to oxygen energy is released and that can be used in ATP synthesis and what's the point of cellular respiration that's right it's to make ATP hopefully that's what you said I'm gonna believe that that's what you said because you're smart and you know this that's great okay so here's what's happening there so we have c6 h-12 o-6 called glucose plus 602 molecules called oxygen that becomes carbon dioxide co2 water h2o and energy okay so if you look at this equation you'll notice that it is exactly the opposite of the photosynthetic equation it's just the same thing backwards if you can remember plants like water Sun and co2 to make glucose and oxygen flip it and now boom suddenly you know the cellular respiration equation it's very convenient but no matter how bright you think you are that energy is not going to be sunshine coming out of you okay it's called energy ATP is what we're talking about here okay so we have glucose that were mixing with oxygen because we eat things that we breathe so we're getting glucose and we're getting oxygen and we're turning that into co2 comes out in your little hot breath right water I'm not talking about like you produce a whole bunch of water but if you go on a mirror it fogs up not because your breath is hot I mean maybe right but then it's also turning the mere foggy because of the water vapor that is coming out of your mouth right and then energy is in the form of ATP because what's the point of cellular respiration to make ATP you're correct okay so here you can see that our glucose molecule c6 h-12 o-6 says it becomes oxidized okay so oxidized o IL oil oxidation is lost we're removing electrons here because we have lost our hydrogen's are gone right and then with our oxygen our six oxygen molecules they become reduced reduction is gain rig right and we're adding in electrons they're in the form of hydrogen so it's a redox reaction that's occurring okay so we're going to go over the stepwise energy harvest of nad plus and the electron transport chain okay so there's an electron transport chain and photosynthesis and there's also an electron transport chain and cellular respiration so in cellular respiration we have glucose which is the main thing that we're talking about and other organic molecules that could be anything else that you're eating that are gonna be broken down or catabolized broken down a catabolic reaction in a series of steps and live like is a lot of steps okay so the electrons from organic compounds like glucose are usually first transferred to nad plus notice that there's no P here NADPH is in photosynthesis that's where I like to think about the P coming in we're not talking about photosynthesis so there is no P here okay so electrons from our organic compounds glucose are usually first transferred to NAD+ which is a coenzyme it's just something that functions with the help of an enzyme so as an electron acceptor right because it's going to be accepting those electrons nad plus functions as an oxidizing agent during cellular respiration so for each NADH which is the reduced form of nad plus because it has gained electrons represents stored energy that is that has tapped tapped into to you to synthesize our ATP inside of the mitochondria okay so for each nadh that has a stored energy in it that we can use to then create ATP so nadh can be turned into ATP NAD+ does not have enough energy to do that yet we have to add electrons to it by reducing it so this is what nad plus looks like okay and then when we add hydrogen to it from your food then it becomes reduced okay and that's going to create our NADH which then has energy that we can turn into ATP so nadh passes the electrons to an electron transport chain and unlike an uncontrolled reaction the electron transport chain passes electrons in this series of steps inside of one explosive reaction oh it's instead of one I supposed to reaction it's so if you imagine like a bouncy ball going down or like a slinky going down a whole bunch of stairs or something you're kind of like changing the energy state we looked at this and we looked at photosynthesis so you guys already know that the electrons are getting passed through different photo systems and photosynthesis and here it's just different enzymes that they're passing through and each time they're going into a lower lower energy state so you're not just having this huge like combustion reaction you're having a series of a whole bunch of little tiny reactions it's just kind of like passing the torch down to the next protein but you're just passing the electrons through and then of course at the end is where you're gonna have the largest payoff of ATP that we'll talk about in a little bit okay so our oxygen pulls electrons down the chain and an energy yielding tumble so like I just said it's kind of like if you imagine a bouncy ball going down the stairs it's gonna hit each of the stairs and as it's going it's going to be lower lower energy the energy yielded is used to help us to generate our ATP molecules that is the fuel of our bodies we need it to do almost everything so the stages of cellular respiration and overview here so we have glycolysis is the very first right there's three overall steps that we talked about so harvesting the energy from glucose has three major steps okay so the first one is glycolysis glyco refers to sugar lysis means to break the word itself literally means break sugar okay will that make sense is a catabolic reaction we're going to be breaking it apart and what are we breaking apart glucose because that's the thing that we're talking about the organic molecule that we're using okay so it breaks down glucose into two molecules of something called pyruvate glucose is a six carbon molecule and each pyruvate is a three carbon molecule it's just like you took it and you snapped it in half that's gonna be very important later okay pyruvate oxidation and the citric acid cycle are the next part so you have to turn pyruvate into like it another substance before it can actually go into the citric acid cycle but that's going to be the complete breakdown with glucose okay and then lastly we have oxidative phosphorylation which accounts for most of the ATP okay that's what we're gonna be generating most of it so that's gonna be through the electron transport chain so really I like to call the three steps glycolysis citric acid cycle et Cie for electron transport chain those are the three major steps of the overall process of cellular respiration and like I said there are both anaerobic and aerobic cellular respiration if we just say cellular respiration and we don't specify it's safe to assume we're talking about aerobic cellular respiration if I indicated it's anaerobic then that would be a different processors we'll talk about later okay but if it doesn't specify it's safe to say that it is aerobic cellular respiration which does go through all three of these stages in order to produce ATP so the formatting here is a little bit off things textbook company but anyway this is showing you the color coding for the rest of the presentation so glycolysis is going to be teal you have our sacred citric acid cycle that's going to be more of this like orange II salmon color and then you have oxidative phosphorylation which is the electron transport chain and chemiosmosis which is going to be more of this like light lavender a purpley color so that's going to be true for the rest of the presentation and also the text if you happen to be using the same textbook as my kids they're using the the Campbell biology and focus textbook I believe that this one's like the 10th edition or something but it's true for any of Campbell's biology textbooks the color coding is the same so here's an overall picture of what's happening and like I said the color coding here it's nice because glycolysis is in that teal you have the citric acid cycle that's going to be the salmon color and then we have the electron transport chain it's gonna be purple okay so this is showing you the overall process and I think that this is another really great image that you should be coming back to to kind of see where everything is happening this is showing you the overall reaction of cellular respiration again assuming it's aerobic where everything is going in coming out being made okay so the process that generates most of the ATP is called oxidative phosphorylation because it's powered by redox reactions oxidative phosphorylation accounts for almost 90% of the ATP generated in the in cellular respiration the process of cellular respiration so we have the three steps we have glycolysis we have the citric acid cycle and then we have the et Cie so oxidative phosphorylation occurs with the et Cie okay so ninety percent of it comes last so just remember that that's at the very end okay I'm a smaller amount of ATP is formed in glycolysis and the citric acid cycle by substrate level phosphorylation so substrate level phosphorylation does not generate as much energy as oxidative phosphorylation and if you look back at this picture it kind of shows you that here in glycolysis its substrate level and citric acid its substrate level and then in our oxidative phosphorylation step that includes the electron transport chain and chemiosmosis its oxidative phosphorylation that generates a lot of ATP that's why these little ATP clouds are small and this one's larger okay so that will be something that you're probably gonna be asked on your exam to know the differences between oxidative phosphorylation and substrate level that oxidative makes more ATP for each molecule of glucose that's degraded into our carbon dioxide that you're going to exhale and water this you're going to exhale the cell makes up makes up to 32 molecules of ATP this assumes that like nothing messes up this assumes that's like in a perfect world it can create up to 32 molecules of ATP so we have enzymes that are going to help us do this right we've talked about this before so this is when we have an enzyme and a substrate you have a phosphate is attached to the substrate it's going to be cleaved and added to ADP in order to create ATP and a product so that's what this enzyme is showing you this is the reaction at the enzyme is catalyzing here it's just speeding up this reaction having a substrate that has a phosphate group on its substrate level phosphorylation okay it's gonna donate that phosphate group to ADP which is adenosine diphosphate to make sure we have a denizen triphosphate which is actually cellular energy and then you will have a product coming up as well okay so glycolysis is our first step so glycolysis harvest chemical energy by oxidizing glucose into two pyruvate okay so glycolysis the word itself means sugar breaking or sugar splitting so it breaks down glucose into two molecules of pyruvate like I said glucose is six carbons pyruvate each one is three carbons three plus three is six that checks out so glycolysis occurs in the cytoplasm I'm gonna say that again glycolysis occurs in the cytoplasm nah didn't I say that cellular respiration happens inside that mitochondria but then this is happening inside the cytoplasm like why is that a thing that call us this is special happens in the cytoplasm we'll talk about why it's special later when we talk about evolution towards the end okay glycolysis happens in the cytoplasm not the mitochondria in the cytoplasm and who has cytoplasm every single cell has cytoplasm these two things are gonna go together later it's gonna be important okay so you have two major phases you have the energy in s-mint phase and the energy payoff phase okay so glycolysis occurs whether or not oxygen is present so this means that glycolysis is occurring in both aerobic and anaerobic cellular respiration which is also called fermentation okay glycolysis occurs no matter what so this means that every organism is doing glycolysis and like I said every organism also has cytoplasm so that's convenient does every organism have a mitochondria no because you know prokaryotic cells which are bacteria PB no no right prokaryotic bacteria in a nucleus no membrane bound organelles so a bacterial cell does not have a mitochondria which means that it can at least do glycolysis here because glycolysis occurs in the cytoplasm and it absolutely has cytoplasm so that's very important okay so we're gonna be talking about the process of glycolysis so you have the investment stage and the payoff stage that we'll be getting into so here's the overall reaction that you have the energy investment you're gonna be using to ATP but then later you're gonna be generating for ATP for a net of 2 ATP okay so this is the investment phase so all these little numbers 1 2 3 4 5 that are in this picture all those members represent enzymes and all these enzymes have to catalyze these reactions it's important to understand that if it's a kinase you were going to be either adding or removing a phosphate from something okay so hexokinase hexo is referring to 6 so 6 carbons kinase tells you it's moving a phosphate group so glucose becomes glucose 6-phosphate that means that on the sixth carbon we've added a phosphate glucose 6-phosphate where did that phosphate come from well we used an ATP to do that so we took ATP and we made it into ADP that extra phosphate we slapped onto the sixth carbon of glucose so hexa six kinase means it moves the phosphate hexokinase took the phosphate from ATP and that too glucose to make glucose 6-phosphate this is how you should go through each one of these steps if I do that for all of these ten reactions we're gonna be here for like seven and a half hours okay but that's how these things work if you see something like number 2 that says isomerase phospho glucose isomerase it means it's rearranging the the molecules that are present here we have glucose 6-phosphate that becomes fructose 6-phosphate the phosphate doesn't move but it's the arrangement of the bonds that are going to change isomerase just just kind of rearranging so if it's a kinase it's moving a phosphate if it's an isomerase it's rearranging okay so those are the two really important ones that you'll see used throughout the ten steps this is also outlined in your textbook okay like literally step number one in your textbook says a hexokinase transfers a phosphate group from ATP to glucose making it more chemically reactive the charge on the phosphate also traps sugar in the cell and then for Sept 2008 is converted to fructose 6-phosphate so you do need to kind of know what's happening in these steps so what these enzymatic names are telling you okay but this is the investment phase where you're putting in two ATP and this is the energy payoff where you're gonna be creating four so if you four and you take away two you've really netted two okay so like I said this is if you want to know the pictures for this and this in our textbook that we're using the tenth edition is on page 140 okay you do need to know all of those little tiny steps okay so after pyruvate is oxidized because the whole point of all of this was to make pyruvate and you see these little twos that are in front of everything this is saying that glucose has already been split so when we make our g3p here we're gonna be using two of these because you only see three carbons and there's really six carbons so you're gonna create 2 1 3 bisphosphoglycerate you're gonna be creating two 3 faso glycerides okay so that's little twos mean that's how it looks like there's like two cards almost showing you that there's two of them okay so after our pyruvate is oxidized the citric acid cycle completes the energy yielding oxidation of organic molecules so basically glycolysis it took glucose it's split it in half and we made two of these things called pyruvate and there's 1 2 3 right where we have 3 carbons we essentially took glucose snapped it in half boom we have 2 pyruvates ok now what this is saying is that we're gonna hand off that pyruvate to the citric acid cycle but there's one step that has to occur in between in order to get pyruvate into a usable source here for this product ok so in the presence of oxygen that's important in the presence of oxygen means it's in an aerobic condition ok pyruvate enters the mitochondrion so it goes inside the mitochondria ok and this is gonna be in our eukaryotic cells which is animals and plant cells notice it didn't say bacteria cuz bacteria don't have a mitochondria cuz we just talked about that and that's why they only do click closest and we'll get back to them in a little bit ok ok so we have our pyruvate enters the mitochondria if there's oxygen ok where oxidation of glucose is completed so we're breaking down glucose in order to make ATP well we broke glucose in half well that's not ATP yet we got to keep going ok that's what we're gonna do inside of the mitochondria when we have oxygen so before the citric acid cycle can begin we have to change pyruvate pyruvate must be converted to acetyl coenzyme a which is abbreviated acetyl co a which links glycolysis to the citric acid cycle it's just kind of a rearrangement that has to happen in order for acetyl co a to actually be fed into the citric acid cycle correctly so right now we're on the salmon section which is pyruvate oxidation and then you have citric acid cycle so like I said we're gonna do one little tiny step before we go into the citric acid cycle so you have pyruvate from glycolysis that has to Molly there's 2 molecules per glucose because glucose has 6 carbons and his three carbons so you will create two pyruvate from one glucose okay and then you're gonna go through a series of reactions here in order to form acetyl co a so this is where your carbon dioxide is actually created okay and then we have our co a our seat alcoa way that's going to be here that's going to help us feed into the citric acid cycle so notice that you have six carbons in glucose when you split them in half you have three and three that's pyruvate three carbons here you have three carbons when you release the co2 you now have two carbons left over so we have a two carbon containing molecule that's being fed into the citric acid cycle so the citric acid cycle is also called the Krebs cycle they're the same thing just like Calvin cycle and dark reactions mean the same thing citric acid cycle and the Krebs cycle mean the same thing okay it completes the breakdown of pyruvate to carbon dioxide so the cycle oxidizes organic fuel like glucose derived from pyruvate okay we're gonna be generating one ATP molecule three NADH which can later be turned into ATP and one fadh2 which can also be turned into ATP per turn so we're gonna be creating ATP nadh and fadh2 for each one of these pyruvate that we're going to be oxidizing and breaking down so now we are officially in the citric acid cycle why because we've taken that pyruvate we've changed the form a little bit we've created a seat alcoa which is a two carbon containing molecule that we're now going to feed into the citric acid cycle so this is the overall process does it look like a lot yes but again all these little number one two three four all the way through eight okay those are all representing different enzymes that are going to be helping to create each of these little intermediates before we get to our products and the point of all this is to be creating these nadh --is ATP fadh2 because what are we what are we doing this whole process for cellular respiration the point is to create ATP so if we can use nadh and fadh2 to create ATP this is a step the right direction and of course creating a teepee that's also another step in the right direction so we are breaking down glucose all the way in order to use the products that we're making here nadh fadh2 ATP to generate more ATP okay so acetyl co a comes in you have a series of reactions to create citrate isocitrate alpha-ketoglutarate succinylcholine by all of these intermediates okay but what I do want you to know is what's happening here all of these different enzymatic reactions that we have the purpose of all of these you know like you're like well what matters if we have you know citrate versus oxaloacetate who cares well I mean look at the differences in the carbons okay we have a difference in the carbons we have our products coming out that we're looking for because they're going to go on to our third step called the electron transport chain which is our oxidative phosphorylation okay so the point of the citric acid cycle is to further break down our glucose molecule all the way and then we're releasing these little energy harnessing you know products along the way that are then gonna go into the next stage so again in your textbook it spells out what each of these little steps actually does what I want you to know is that each one of these little steps is important in order to create our fadh2 NADH and ATP so the citric acid cycle has eight steps total honey know there's eight of them okay they're all numbered those all represent the different enzymes that are going to be functioning here okay each catalyzed by specific enzyme so the acetyl group of acetyl co a joins a cycle by combining with oxide lacet eight to form citrate do you see what's happening here oxaloacetate right here is going to meet up with our acetyl co a to create citrate this looks very similar to photosynthesis if you ask me okay the processes are kind of similar okay I'm sorry I went throw away okay so acetyl co a group of acetyl co a joins the cycle by combining with our cell acetate saturate boom there's our first product okay the next seven steps decomposes citrate back to oxaloacetate again we're having to regenerate something here which sounds again very similar to photosynthesis making the process of cycle so as you go through you a break down citrate isocitrate alpha q occluder a sectional co a sucks in a fumarate malate back to oxaloacetate why because you're gonna have another acetyl co a that comes in and it needs to combine with another oxaloacetate so this makes it a cycle it is a cyclic function here because you have to regenerate that oxaloacetate in order to accept the next acetyl co way that's coming in in order for us to generate all of these extra nadh is ATP and fadh2 okay so the nadh and fadh2 produced by the cycle relay the electrons extracted from food to the electron transport chain so essentially these were electron acceptors that have accepted the electrons and now they're going to carry them over to the electron transport chain to drop them off that way we can make our ATP so during oxidative phosphorylation chemiosmosis couples electron transport to ATP synthesis okay first of all before I go on let's talk about chemiosmosis okay so you know what else Moses is osmosis is the movement of water from high to low concentration through a selectively permeable membrane we're not really talking about water here okay we're gonna be talking about chemicals okay so specifically we're actually going to be talking about our hydrogen that's going to be diffusing through the membrane so a process in which energy stored in the form of the hydrogen ion concentration gradient right you have a gradient of hydrogen ions as they cross the membrane and they're used to drive cellular work like the synthesis of ATP it's called chemiosmosis so it's actually just referring to our chemicals or in this case our hydrogen ions that have created a gradient you're pumping them on one side of the membrane and then as they diffuse back in it's called Kenny Moses and that gradient is going to help us drive the production of ATP okay so following glycolysis and the citric acid cycle nadh and fadh2 account for most of the energy extracted from our food these two electron carriers donate electrons the electron transport chain which powers ATP synthesis via oxidative phosphorylation so the pathway of the electron transport chain okay the electron transport chain is the is in the inner membrane the cristae of the mitochondria remember that it kind of looks like a beam with like a little wavy line in the middle of it it's a double membrane organelle so we're talking about the inner membrane of the cristae right inside of our mitochondrion most of the chains components are proteins so a lot of them are transmembrane proteins some of them are integral proteins which exist in multi protein complexes so we'll look at a picture of that in a minute it literally is just a whole bunch of different proteins that are close together in this membrane the carrier's alternate alternate reduced and oxidized States so these are all redox reactions that are happening as we're passing the electrons through because they're accepting and then donating electrons right so they're getting them from the protein that came before and then donating them donating them to the next protein so the electrons drop and free energy as they go down the chain and are finally passed to oxygen so oxygen is our last electron acceptor forming h2o which is called water and in this case we're forming water vapor that comes out of your body in your breath so we've made it to part three the oxidative phosphorylation electron transport chain and chemiosmosis and remember this is where we're gonna get the biggest bang for our buck we're gonna make a lot of ATP here because it's oxidative phosphorylation instead of substrate level phosphorylation which was happening in the first two steps so we have a whole bunch of these little protein complexes here and you can see that we have kind of like it's going down and our free energy so like I said it's like bouncing and bouncy ball down the stairs and starts high and low so we will end in lower energy than where we started and so this is the overall process of the electron transport chain you just have a bunch of handing off that's occurring of all of these different electrons right so you know that you have nadh coming in and fadh2 coming in they come in in different steps that's fine okay they're gonna be donating their electrons and to then become nad plus and F ad which can then go back and pick up more electrons to keep bringing them it's kind of like a go-between okay so the electrons are transferred from nadh or fadh2 to the electron transport chain they're donating them that's what's happening here okay and if they're losing oxidation is loss which means that these guys all these proteins are getting reduced okay so the electrons are passed through a number of proteins including cytochromes each with an iron atom that's just the cytochrome is to oxygen oxygen is the final electron acceptor and it becomes water okay the electron transport chain generates no ATP directly but what does happen here it breaks large free energy drop from food to oxygen I'm into smaller steps that release energy and a manageable amount we have the energy coupling mechanism here that we're gonna talk about chemiosmosis which I just explained earlier which is how we've pumped all of our hydrogen on one side of the membrane and then as it diffuses back down we're gonna use that to drive the synthesis of ATP through ATP synthase so the electron transfer and the electron transport chain causes proteins to pump our hydrogen ions from the mitochondrial may take matrix into the inter membrane space between the two membranes okay so then our hydrogen then moves back across the membrane because we've generated a high concentration now it wants to go to the low concentration passive transport it's gonna move back across that membrane even though we just pumped it out we pumped out a whole lot and now we want to bring it back in through diffusion it's gonna be passing through a protein complex called ATP synthase it's a protein complex that generates ATP like ATP synthesis ATP synthase that's got its name remember 8se tells you it's an enzyme or a protein okay so ATP synthase uses the exergonic flow of our hydrogen ions to drive phosphorylation of ATP so this is an example of chemiosmosis it's using the worker it's using the energy of our hydrogen ion gradient to drive cellular work okay so hopefully the third time through that made a little bit more sense to you they were using this gradient to help us it's literally like a protein that spins we're literally using those hydrogen's to help us spin our protein to create ATP so here's what the overall picture looks like okay you have our hydrogen's that are on the outside that are coming back in there in the intermembrane space that orange part and are coming back into the mitochondrial matrix so you have our hydrogen ions that are flowing down their gradient they're going to enter a half channel in the stator up at the top which is anchored into the membrane then we have our hydrogen ions that are going to enter binding sites within the rotor which is going to be changing the shape of each of the subunits so that the rotor will actually spin like I said within the membrane you can see that there that arrows trying to show you it's gonna spin each of our hydrogen ions makes one complete turn before leaving the rotor and then passing through a second half channel in the stator into the mitochondrial matrix so it's actually crossed that membrane and the spinning of the rotor as each one goes through causes an internal rod to spin as well and the raw actually extends like a stock like into like a like the knob that's below it which you can see there which is held stationary by part of the stator and then turning the rod activates a catalytic site in the knob that produces ATP from ADP and inorganic phosphate so essentially as all of our little hydrogen ions are coming through they're causing the rotor to spin and it's going to help to activate the catalytic site in the knob the or region that's going to take ADP combine it with a phosphate and create ATP so this is ATP synthase as the name of this little engine here and it's like a molecular mill it's constantly producing ATP as long as we have generated that hydrogen ion gradient okay so the energy stored in our hydrogen ion gradient across the membrane couples with redox reactions of the electron transport chain to ATP synthesis so the hydrogen ion gradient is referred to as a proton motive force which emphasizes this capacity to do work because it H+ is a proton proton motive force it's helping because it's mobilizing and it's creating energy there we go okay and so that whole process is chemiosmosis where we have the chemicals called hydrogen ions coming down kind of like osmosis moving from high to low concentration it's literally pushing back through the membrane to drive that rotor in order to produce our ATP so that's our last step there that's where we get most of our ATP from so here's another picture of what's happening you have the electron transport chain and then chemiosmosis happening last okay but the whole thing is called oxidative phosphorylation so the electron transport chain is when we have all these little purple multi protein complexes where you have the nadh and fadh2 that come in and they're donating the electrons you can see that here carrying electrons from food so we made these things in the citric acid cycle by breaking down pyruvate into acetyl co a and then going all the way through and regenerating oxaloacetate right so then we can do the next pyruvate that gets turned into a CoA we're making these nadh and fadh2 s during that process which bring and drop off electrons here and then our electrons kind of flow like through all of these different protein complexes reducing an energy through each complex that they go through but all the while they're actually causing these hydrogen ions to move to the other side of the membrane and then as we have a large portion of hydrogen ions built up on the matrix side they're going to become early inter membrane space they're actually going to be coming back down driving this rotation of the rotor and ATP synthase through chemiosmosis to create where most of our ATP comes from so this whole process is oxidative phosphorylation electron transport chains were transporting electrons and then chemiosmosis is when we're relying on that proton motive force of our hydrogen ions to drive the production of ATP through ATP synthase so an accounting of ATP production of cellular respiration we're gonna talk about where everything is made so during cellular respiration most energy flows in the following sequence glucose to NADH to the electron transport chain to the proton motive force to ATP so you know that you use glucose you're gonna break it down and this is what you're gonna be creating here it's gonna carry electrons the electron transport chain or we're going to be transporting just electrons through all those protein both protein multi-protein complexes and then that's going to help us build up a proton motive force on one side of the membrane as it diffuses back down we're going to be generating a lot of ATP okay so about 34 34 percent of the energy and a glucose molecule is transferred to ATP during cellular respiration making roughly 32 ATP that's like our maximum okay there are several reasons why the number of ATP molecules are not known exactly first of all it can kind of vary from what you're eating to the type of organism also if any of those like little reactions along the way if something like happen to mess up there's a whole lot of reasons why there could be a fluctuation an ATP but like ideally we're just gonna say it makes 32 ATP okay so here's our overall reaction again and this is going to be our maximum glucose number we're doing the math along the whole way so we have our three steps to cellular respiration we pollicis we have the citric acid cycle and we have the et Cie which we're going to call that whole thing oxidative phosphorylation so remember that these two steps are substrate level phosphorylation because we're just dealing with phosphates on substrates and over here it's actually oxidative phosphorylation okay so glycolysis we put two in we make four that's a net of two ATP in the citric acid cycle remember that you're gonna make nadh fadh2 but then also two ATP because you're gonna make it turn twice for each one glucose molecule because you're gonna put two pyruvate and then they become two acetyl co a and then each one of those acetyl choline needs to go through that cycle okay and then we're going to create our nadh and fadh2 that are gonna go into phosphorylated phosphorylation the electron transport chain in chemiosmosis to generate about 26 or 28 ATP with the functionality of that ATP synthase that's spinning to create ATP so 2 + 2 + 26 - 28 is roughly 30 - 32 ATP per one molecule of glucose that's pretty efficient process it makes a lot of ATP for one glucose molecule and you consume a lot more than one glucose molecule at a time remember that the energy can come from stuff that's not glucose of course if you eat fat if you eat protein you're just not going to be entering at you know the first step of hexokinase in glycolysis you might be entering somewhere else into the overall cycle but having glucose actually goes through every single one of the steps the ten steps of glycolysis and then you have the eight steps in the citric acid cycle and then the electron transport chain and chemiosmosis right it's the whole thing okay so one molecule is going to generate 30 - 32 ATP for us the alternative here is fermentation and anaerobic respiration so remember that this reaction starts with glycolysis but then it moves into in the presence of oxygen it's going to move into the mitochondria okay this is aerobic cellular respiration and fermentation or an aerobic cellular respiration cellular respiration does not have oxygen so most cellular respiration actually requires oxygen to make ATP okay without any of this oxygen the electron transport chain will cease to operate because that's a final electron acceptor and there's nothing there to accept electrons it's not going to work okay in that case glycolysis couples with fermentation or anaerobic respiration to produce ATP so we're going to take a look at that process and how it's different from our ideal situation of aerobic cellular respiration with oxygen so an aerobic cellular respiration uses an electron transport chain with the final electron acceptor that's not going to be oxygen for example we could use sulfate there's no oxygen available well then you can't use any oxygen that makes sense so fermentation uses substrate level phosphorylation instead of an electron transport chain to generate ATP so you know that substrate level phosphorylation is really inefficient compared to our oxidative phosphorylation but if that's not an option for you then you have to just use substrate level phosphorylation so different types of fermentation fermentation consists of glycolysis plus reactions that generate eight NAD+ which can then be reused by glycolysis so we have two common types are alcohol fermentation and lactic acid fermentation so you know like when you're running and you might feel burning in your legs or you're lifting weights and you feel burning in your arms that's actually lactic acid so does that mean that there's no oxygen in your body no because then you'd be dead but it means that maybe your muscles aren't getting quite enough oxygen so some of your cells are starting to do lactic acid fermentation so a byproduct here is lactic acid and that's what causes the burn we also use alcoholic fermentation to create alcoholic beverages through fermentation processes like beer and wine because alcohol ethanol is a product of that so an alcoholic fermentation pyruvate is converted to ethanol in two steps the first step releases carbon dioxide from pyruvate and the second step reduces acetaldehyde to ethanol and then alcohol fermentation by yeast is used in our brewing winemaking and baking processes and actually like when you're making bread you use yeast and yeast do alcoholic fermentation does that mean you're gonna get drunk off of eating bread oh because you're actually cooking it in the oven it actually burns off of any of the little tiny amounts of alcohol that are being created right but all the holes in your bread are actually just where carbon dioxide have accumulated from that little tiny organism that was doing alcoholic fermentation so that's pretty cool um here's the overall process for alcoholic fermentation and lactic acid fermentation you see that they both utilize glycolysis because glycolysis happens in the cytoplasm and all cell types have cytoplasm so there is no mitochondria happening being utilized here whether or not it's in the sound cool whatever it's not being utilized because there's no no oxygen or not enough oxygen present so you can see that an alcoholic fermentation you're going to be generating to ethanol at the end and then lactic acid fermentation you're gonna be generating to lactate at the end and that's what causes the burning sensation in your muscles because we use lactic acid fermentation when there's not enough oxygen present for all of your cells to be doing efficient cellular respiration but why do we do this process it hurts us why do we do it because your cells still need energy like even if it's not a lot of energy because you're only making two ATP here versus the 3232 that you could be making if you have enough oxygen right but if your cells just stopped making any ATP then they're going to stop functioning period right so even though lactic acid fermentation is not ideal because it makes a very very small amount of ATP well we still need ATP so some ATP is better than zero ATP which is why your body switches over to this process and for things like yeast cells they're very small so having this two ATP as its sole source of energy you know that's not like the worst thing in the world for it right for us if all of our cells only made two ATP at a time from consuming like uh from consuming glucose we'd be in some trouble we're very large organisms that are complex now you've got all these different organ systems trying to keep us in homeostasis all the time we would probably not survive on that right but a little yeast cell or a bacterial cell they're gonna be able to function on just two ATP because they don't have 12 organ systems constantly trying to function to keep them alive right so it makes sense and in these smaller microscopic less advanced less complex organisms that they could function off of fermentation also just their location might require that as well right but we as human beings we would need to utilize more ATP in order to keep ourselves functioning so this is kind of like a last resort sort of thing not an ideal situation but a situation to at least be generating something so when lactic acid fermentation pyruvate is reduced by NADH forming lactate as an end product with no release of carbon dioxide lactic acid fermentation is used by some fungi bacteria and also we use it to make cheese and yogurt life tick acid fermentation makes cheese and yogurt it's kind of why they have that unique flavor that they have human muscle cells these lactic acid fermentation to generate ATP when oxygen is scarce like I said it's kind of like the last resort like hey we still need to make ATP maybe it's not the ideal situation because we're only getting two but we're only doing glycolysis it's just one step really okay comparing fermentation with anaerobic and aerobic respiration so they all use glycolysis like I said every single thing uses glycolysis they're gonna net two ATP from that because you have the input the investment and the payoff so you put in two you make four you up net two okay to oxidize glucose and harvest a chemical energy from food in all three of these processes NAD+ is the oxidizing agent that except accepts electrons during glycolysis which again is our first step that happens in the cytoplasm and the processes have different final electron acceptors and organic molecules such as pyruvate or acetaldehyde in fermentation and oxygen and cellular respiration and regular aerobic cellular respiration because we have oxygen right and then in cellular respiration you're gonna produce in aerobic cellular respiration you're gonna be producing 32 ATP per glucose molecule but in fermentation you're gonna be producing 2 ATP per glucose molecules so it's a lot less efficient but like I said depending on the kind of organism that you are or the surroundings that you're you know living in you might not need the 32 ATP we do right we just make the 2 ATP through lactic acid fermentation that's kind of a last resort we have different organisms that are called obligate anaerobes that carry out only fermentation or anaerobic respiration cannot survive in the presence of oxygen this is common with a lot of different types of bacteria that like if they actually get exposed to oxygen they don't live right so we also have something called facultative anaerobes which are like yeast and many different kinds of bacteria that are facultative anaerobes meaning that they can survive using either fermentation or cellular respiration so they can kind of switch back and forth between the two and in a facultative anaerobe pyruvate is a fork in the metabolic road that leads to two alternative catabolic routes so it goes down one of two different pathways as you can see here so you'd have glucose come in we're gonna make pyruvate and then pyruvate in the presence of oxygen can go into aerobic cellular respiration in the mitochondria perfect awesome that's gonna make your 32 ATP or if there's no oxygen present then we can go into the fermentation pathway and only create two ATP and also have that ethanol our own lactic acid or other products that can be created as well so in evolution evolutionary significance of glycolysis like I said all cells have cytoplasm all cells are capable of doing glycolysis because they all have sin opossum so ancient prokaryotes are thought to have used glycolysis long before there was oxygen in the atmosphere because the colonist doesn't use oxygen yet that doesn't get used until we're in the mitochondria so very little oxygen was available in the atmosphere until about 2.7 billion years ago so early prokaryotes likely only used baikal assist to make their ATP which they'd still get to ATP so what cause this is a very ancient process because it's thought to have derived from ancient organisms like our ancient even like our KN prokaryotes because there wasn't a lot of oxygen on the planet so how could they use oxygen to generate C they can't so they would do the process of glycolysis and that's why we think that this is like further evidence that evolution is real because every single organism on the planet uses glycolysis whether or not it goes on to an aerobic cellular respiration or aerobic cellular respiration every single thing that's alive uses the same process and that's not just a coincidence right that had to be something that was conserved and passed on because it was advantageous in all species so that's really cool that that exists glycolysis and the citric acid cycle connect and other metabolic pathways as well so glycolysis and the citric acid cycle or major intersections to various catabolic and anabolic pathways so this is talking about all the different types of fuel sources and everything that you can be breaking down in your body so catabolic pathways funnel electrons from many kinds of organic molecules not just glucose into cellular respiration so glycolysis it accepts a wide range of carbohydrates like I said we just used glucose because first of all we just talked about how it was made of photosynthesis and then it also hits every single step like for instance if you eat fruit you're eating fructose fructose doesn't enter and do all 10 steps of glycolysis it actually only does nine steps as I call this you skip the first one or maybe the first two it might only do eight steps right but you get to skip some of the steps because the structure of that particular molecule is different which is really interesting proteins must be digested two amino acids and then the amino acid groups must be removed before amino acids can feed glycolysis or the citric acid cycle so proteins take a long time to digest because you actually have to split it all into all the amino acids and then all of those like armed groups have got to be like removed before you can actually go down and break down the actual amino acid to fuel the process of glycolysis to then go into the citric acid cycle and so on fats are digested too sir all that's used in glycolysis and fatty acids the fatty acids are broken down by beta oxidation and yield a CoA that can then be fed into the citric acid cycle and oxidized gram of fat produces more than twice as much ATP as an oxidized gram of carbohydrates which is why the keto diet is such a thing right now because for each amount each gram of fat you consume you're actually generating more ATP per gram compared to a carbohydrate and that's supposed to it takes a little bit longer it's supposed to last with you a little bit longer so you're actually getting more energy from fats than you would from carbs which makes sense while ones like long term energy and one a short term energy as well so these are all the different macromolecules that you can eat your proteins carbs and fats or lipids this is where they all enter in the whole process so you can see that like if it's a carbohydrate it doesn't have to start with glucose and then go down it can be a different type of sugar you can have sucrose like it's split into glucose and fructose glucose goes through normally fructose then skips a few steps and then enters where it would become Faso fructose kinase by a kinase that would then add that phosphate group onto it like right and then the proteins you can see over on the side they can enter in whether you have pyruvate right off the start you can just enter in a pyruvate become a CoA go into the citric acid cycle sometimes your proteins can be broken down and go straight into the citric acid cycle your fats are gonna go into both of the processes of glycolysis and be directly transformed into acetyl co a to then enter into the citric acid cycle so that's why we always use glucose to explain the process to go through the whole thing but then understand that each of the items that you're eating contains different nutrients and each one of those macromolecules is going to be fed into the overall process in a different place but the result is always going to be the same that you're going to go through the three steps or skip the one step and go through steps two and three right and then at the end the amount of ATP that you're gonna generate it's going to be different based on where you entered into the system that's why glucose is also a good example to use because that generates it hits every single step you generate the thirty to thirty two molecules of ATP for that and so our bio synthesis our anabolic pathways the body uses small molecules to build other substances and some of these small molecules come directly from food others can be produced through glycolysis or the citric acid cycle so we can also make smaller molecules that then get built together in an anabolic pathway and here's again our overall inputs and outputs that we've been talking about for each of the steps the overall process of our oxidative phosphorylation this is our electron transport chain and chemiosmosis and then I put this slide in at the end to kind of show you the cyclical relationship I don't know why it's like a little bit off-centered that's okay photosynthesis versus cellular respiration now understand the photosynthesis happens in our autotrophs so these are things that are able to produce their own fuel sources every single thing goes through cellular respiration this is probably the most missed or most you know the thing that's lacking from the comprehension of this whole unit cellular respiration occurs in everything from bacterial cell to you and everything in between right so anything that we that is alive and it requires energy it's going to use cellular respiration now there's different kinds of cellular respiration that we talked about but a lot of kids for some reason don't understand that because something goes through photosynthesis like a plant is going through the sunflower does photosynthesis true it also to Saylor respiration cuz once you have that glucose that's not energy that's sugar you need to break that down in order to get energy called ATP which is the whole point of cellular respiration right so that's the overall process we're gonna talk more about the cyclical relationship in class I hope this helps a little bit I know that it was long thanks for sticking with me please go back and look at the pictures and try to explain them to yourself because that will be a really great way for you to study good with it and I'll see you in the next video

Channel: Science Edu-cate-tion

Views: 13,188

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Keywords: campbell, biology, chapter 7, cellular respiration, anaerobic, aerobic, chemistry and cells, mitochondria, citric acid cycle, glycolysis, oxidative phosphorylation, substrate level phosphorylation, electron transport chain, ap biology, dc biology, campbell biology, biology in focus

Id: SnYL6AblzuY

Length: 65min 57sec (3957 seconds)

Published: Sat Nov 02 2019