Lecture 5 - Cellular Respiration

本站添加: 2026-05-14

[00:00:01]hi everyone welcome back this week we're going to be focusing in on chapter four of our text where we're going to be looking at the process by which our cells are capable of taking glucose and producing atp now remember it's not only glucose but that's going to be our main focus we can also burn or metabolize our fatty acids as well as and it's not as ideal but our amino acids when we looked at cell parts remember the membrane-bound organelle found in the eukaryotic cell that's responsible for the production of atp that acts as our powerhouse that is the mitochondria all right so we're going to look today at the following stages glycolysis pyruvate oxidation krebs cycle and electron transport chain and look at the various regions of the cell in which these different chemical reactions take place cellular respiration also known as cellular metabolism is the oxidation of food to obtain energy now we've talked about this before right that ultimately all of the energy that we obtain as omnivores comes from the sunlight right whether it is that we're eating plants or whether you're eating both animal and plant by-products ultimately the energy is all coming from the sun right now we're not going to be covering plants in the process of photosynthesis but just a quick crash course the uv rays from the sun they interact with the chloroplasts that are specific organelles found within plants and the chloroplasts are responsible for then taking the uv energy that they've received and creating glucose all right and that glucose is ultimately what either the animals are then eating to them produce atp or omnivores such as us that are eating both animal and plant by-products are receiving it from either source right so even if you know you're eating a hamburger and eating that beef patty well that cow at some point was eating grass that's how the cow is able to store up that key energy molecule of glucose in their body now another thing that helps to balance the cycles between the plants and animal kingdoms is that the plants are producing oxygen so they're taking up the carbon dioxide that we're producing through cellular respiration and they're converting that into both glucose which we can use to make energy as well as oxygen which we then use to power aerobic cellular respiration so our main focus for today is going to be on glucose but remember there are other ways that we can obtain energy specifically through fat breakdown as well as protein breakdown what are the macromolecules lipids proteins carbohydrates and nucleic acids now the reason that each of our cells specifically the mitochondria are working to create all of this energy is to create these molecules known as adenosine triphosphate all right i've mentioned atp so far this is what atp stands for now i want you to take a look here at this portion of the molecule so we've got here a nucleotide base adenine which is attached to a ribose sugar which is then attached to in this case three phosphates but what if we only had one phosphate here what does this molecule look a lot like and if you said nucleotides you were right right specifically ribonucleic acid the adenine that makes up a ribonucleic acid looks pretty similar to adenosine triphosphate the only difference is that our atp molecule has an additional two phosphates attached to that phosphate group all right and the reason that we have these phosphates attached here is because the phosphate bonds possess high energy so when we break those phosphate bonds we're capable of releasing that energy in the form of electrons and using that to power different processes within the body so when you break the phosphate bonds here and you release that phosphate group now you have those free electrons to use as energy we now have an adenosine diphosphate molecule all right so when we're producing atp molecules what we're doing is we're recycling the adp molecules that have essentially been used up and we're just adding an additional phosphate on to that adp molecule all right so adp is adenosine diphosphate with two phosphates adenosine triphosphate is our energy molecule with three energy can be released from any molecule that has a carbon-hydrogen bond right because what is it that's actually creating these bonds it's the electrons that are being shared in this case because these are covalent linkages all right so anytime we break the bonds that are holding together these organic molecules we are able to release the electrons and thereby use them in the form of energy right some examples here of molecules that contain carbon hydrogen bonds methane which is your natural gas glucose which is going to be our main focus for today and then also fatty acids right we're going to see how you can break down your fatty acids and take the product of just simply cleaving off two carbons at a time and adding those to an intermediate that feeds into the krebs cycle now the problem with processed foods is that they contain mostly sugar and starch lots of carbon hydrogen bonds so that's great for energy but ultimately once we've then stored up the excess sugar as glycogen and all of those stores are maxed out any excess that we have is going to be converted to and stored as fat another thing too with processing is that typically when we process grains we end up losing a lot of the the key vitamins minerals antioxidants and even in some cases the fiber content right that's the difference between your you know your white bread and your brown bread now with simple sugars right anytime you have an increase in that it's going to cause rapid fluctuations this also tricks your endocrine system because you end up not being satiated which is essentially the feeling of being full and you end up with just more cravings right this is why they say that sugar is addictive it's important to ensure that you are going to be receiving all the healthy fats fiber that you need because the fiber is what's going to fill you up ultimately now during cellular respiration as we're breaking down that glucose converting it into a number of different intermediate molecules there are going to be a series of redox reactions right and that's short form for reduction oxidation during these reactions between two different molecules electrons and hydrogen ions are going to be moved from one molecule to another so with oxidation we're looking at a reaction in which a molecule has lost electrons now remember electrons exist in covalent linkages so you're talking about a carbon and a hydrogen being bound together the electrons are what are holding those two atoms together when we oxidize any compound we are going to be losing electrons and those electrons are going to be passed on to another molecule right and once that other molecule receives those electrons that molecule is said to be reduced this one's an easy one to remember because reduced just think you're if you're gaining negative charges the overall charge would be reduced in that way okay so with oxidization you're losing electrons and with reduction that molecule is gaining electrons now there's a great mnemonic leo the lion says ger that can help you to remember where electrons are coming from and going to all right so first off with leo that stands for loss of electrons is oxidation all right and then with ger gain of electrons is reduction when it's oxidized it's losing hydrogens and electrons and then when it's being reduced it's gaining electrons and thereby gaining the hydrogens now our main focus for today is going to be looking at how glucose is metabolized how we take that glucose monomer and we break it down through glycolysis krebs cycle and electron transport chain to ultimately produce atp now i've been talking about all of our different macromolecules and the three specifically that we see on the nutrition label right our lipids our carbs and then our proteins now something we're going to add to that today is some other information that we get from the nutrition label which is the caloric value well a calorie is the energy needed to be able to raise the temperature of one gram of water by one degree celsius in order to do something like that you would need to add energy into a system right calories are a measure of the amount of energy that we're going to be able to obtain from these different macromolecules once we are metabolizing them in our own bodies for one gram for each of the following macromolecules as well i've included alcohol to give you a bit of perspective here on those fruity alcoholic beverages but with carbohydrates protein and fats what caloric value comes from one gram of those macromolecules so you'll see here carbohydrates and proteins carbohydrates and proteins you're receiving about four calories per gram whereas fat many more calories per gram of fat now there are about 3 500 calories to give you perspective here in a pound of fat if you do the conversion there now that works out too 3 500 calories and a pound of butter now alcohol i put this in here as well because there's about seven calories per gram of alcohol when you think about any kind of sweet alcoholic beverage you've got not only the calories coming from the alcohol but also from the sweetener that's been added to that it's important for us to be aware of what it is that we're taking in when you're younger your body for the most part is able to keep up with whatever it is that you throw at it but it is true when you get older your basal metabolic rate just slows down and so without exercise and increasing your total metabolic rate you really have to ensure that you're taking in a balanced you know diet that's not going to be too heavy on on one food group because for example look at your sugars pro-inflammatory any excess that does not need to be stored up as glycogen would then be converted to fat so it doesn't necessarily if you're eating a low-fat diet if it's high in sugar or refined carbohydrates you know it's still going to ultimately be converted back to fat now there's two types of cellular respiration that we're going to talk about today the first one is aerobic respiration and we're going to look at that where we have oxygen and our cells are capable of using that oxygen to be able to produce a lot of atp in anaerobic conditions or certain organisms that don't have membrane-bound organelles that are capable of utilizing that oxygen they require anaerobic respiration to be able to produce atp we're going to take a look at that as well towards the end one example of an organism that utilizes anaerobic respiration would be our bacteria so the process of aerobic respiration not only requires oxygen but glucose okay anaerobic respiration can occur as long as glucose is there without the oxygen but for aerobic respiration to occur we need oxygen and the whole process is to take this six carbon remember your carbohydrate ratios one to two to one it's following through there to take your glucose molecule combine it with oxygen we then produce carbon dioxide which we're going to breathe out ultimately water and a bunch of atp so a relatively clean burn right and then plants are able to take up that co2 and they're able to produce more glucose and oxygen so it's this perfect circle of life so we're going to spend a lot of our time today focusing on aerobic cellular respiration okay whereby glucose molecule and the presence of oxygen is going to ultimately can be converted into atp now the stages as i mentioned at the beginning are glycolysis pyruvate oxidation the krebs cycle and the electron transport chain we'll be looking primarily at the starting and end products okay for both of these cycles as well as looking at what's being input into the series of reactions and what is the output and i've created charts that i've included along the way but if you just print out one of those fill that in for yourself it'll give you a nice overview of all of the starting and end products that way you can sort of organize in your thoughts where all of these different processes take place within the cell so the first stage is known as glycolysis now glycolysis does not require oxygen you're probably thinking okay i thought you said we're looking at aerobic respiration we are with oxygen we can then move to this next step all right without oxygen we cannot pass from the end product of glycolysis which is pyruvate all right so for aerobic respiration we require oxygen in order for pyruvate to be oxidized within the mitochondria now glycolysis as you can see as it's illustrated here occurs in the cytoplasm of the cell right this is another reason why anaerobic bacteria are capable of utilizing glycolysis to produce their own energy because they don't have membrane-bound organelles remember the prokaryotes don't have membrane-bound organelles so they don't have a mitochondria that's capable of producing all that atp so within their cytoplasm they're going to be simply breaking down glucose producing pyruvate and there's a way that they can recycle that pyruvate for us because we are aerobic we utilize that oxygen to then allow pyruvate to become oxidized with a mitochondria which sets off another cascade of reactions with the ultimate production endpoint being more atp so stage one is glycolysis and glycolysis occurs within the cytoplasm as i just mentioned and it does not require oxygen right so that makes it the main energy source for those prokaryotic organisms because they don't have mitochondria they do not have any membrane-bound organelles and so they are just going to simply be taking that glucose breaking it down into pyruvate producing a few net atp and continuing that cycle over and over and over again as we're gonna see a little bit later there's a that's a lot of work just to produce the amount of atp that they're producing to give you a big picture perspective the net production of atp here in glycolysis is about 2 atp we produce roughly 38 atp throughout all of the different processes so definitely aerobic respiration has its advantages for us now there's a sequence of chemical reactions as i mentioned before a number of different steps that have been broken down into just a few that you can see here but ultimately we are taking a six carbon glucose molecule and through different processes phosphorylation and then splitting it up into two we are producing two three carbon pyruvate molecules so your starting product is your six carbon glucose that glucose is then split up into two three carbon pyruvates now along the way to actually get this started we require the input of atp and atp remember is adenosine triphosphate that's our energy molecule when we break the bonds of these molecules that energy in the form of electrons is then used to form atp right that's known as phosphorylation now phosphorylation is the process by which we will take our recycled adp the diphosphates and add a phosphate to it to then produce atp all right so when we use that term that's being phosphorylated that means that we are adding a phosphate onto the adp molecule to produce the atp now we have two different types of electron carriers in their oxidized form they exist as nad plus and the other one is fad right when they are reduced remember they're going to be gaining electrons and hydrogens the nad plus becomes nadh and the fad is going to become fadh2 we're going to see that other molecule a little bit later two different electron carrier molecules their whole purpose is to become reduced here in glycolysis reduced in the krebs cycle and then ultimately oxidized later on so they can give off those electrons to our proton pumps all right so here in glycolysis for each three carbon we're gonna have an nad reduced and we're gonna have two atp reproduced so if you look at all of these totals it looks like we're producing four atp from glycolysis but one thing you have to remember to kick off the process of glycolysis we require an input of 2 atp for the phosphorylation to occur here so if you consider the net then you have 4 that are being produced two is your input so our total net would be two atp okay we have that here so you have four atp output two atp input and it gives you a total net from glycolysis of two atp per glucose molecule now glycolysis as i mentioned is the only way that an organism can derive energy from food in the absence of oxygen in anaerobic conditions they must continue to just recycle their electron carriers to be able to then go back through the cycles breaking down more glucose producing that two net atp so here's a summary you need to know the starting molecules we're starting with glucose glucose has six carbons how many atp molecules are required for glycolysis to occur that would be our two the number of atp molecules made that would be four that's the total what is our net our net would be the four minus the two that we input so that would be a net of two atp molecules per glucose how many nadh molecules did we form two and then what is the finishing product what was that final end molecule that was the pyruvate with three carbons each so you can see we've maintained the number of carbons in this case all right we've gone from a six carbon glucose to two three carbon pyruvates yielding two atp and two nadh okay so this is the chart i was mentioning um you can fill it in by yourself or you know go to one of the last slides where i filled it in for you and you can just print that off for your own reference so glycolysis is taking place outside of the mitochondria the rest of these reactions are going to take place inside right in the presence of oxygen but it takes place in the cytoplasm it's why any organism can use glycolysis to produce energy we start with one glucose we input two atp and we start with two oxidized nad plus molecules right those are the electron carriers they need to be reduced they need to take on those electrons so what do we end up with the two pyruvate molecules four atp total two net and then two nadh and we're gonna see where nadh and fadh2 come into play here as the starting products of the electron transport chain all right we're going to move on now to stage two all right so glycolysis we have produced our two nadh molecules produced two net atp and now we are left with two three carbon pyruvate molecules as i mentioned in the presence of oxygen pyruvate is able to then leave the cytoplasm and enter into the mitochondria where then it goes through a process of oxidation so it's here in the mitochondrion now that that three carbon pyruvate is going to be oxidized which means it's going to lose electrons so what ends up happening those electrons go off to the another nad plus to reduce it into nadh and then your end product will be a molecule known as acetyl co a co stands for coenzyme coenzymes you can also say acetyl coenzyme a right and you might be thinking okay so we started with three carbon and then we end up with a two carbon acetyl-coa well what's happening here well this carbon gets bound to that oxygen right in the presence of oxygen we can oxidize pyruvate and so that carbon that's being lost because we've gotten rid of the bond there and we've given away the electrons the carbon then can be bound to oxygen which we then can get rid of and breathe out now remember how many pyruvate are we starting with per glucose molecule we are starting with two pyruvate per glucose and so ultimately we are going to be producing two more co2 molecules and two nadh molecules as well as two acetyl coa that will each then enter into the krebs cycle okay so as i mentioned before the specific enzyme that's going to be cleaving that bond there between the carbons is known as pyruvate dehydrogenase and the single carbon is going to leave as part of that co2 molecule those hydrogens as well as electrons are going to be removed from pyruvate which is oxidation and then they're going to be donated to the nad plus reducing it into nadh so now we're left with two acetyl coa compounds so let's take these molecules and let's take a look where they're going to end up in the krebs cycle so now we're into the mitochondria two pyruvate were oxidized we also needed to start with two nad plus molecules we ended with two acetyl coa two reduced nadh and two molecules of carbon dioxide okay so we are in aerobic respiration we have broken down glucose into pyruvate we've then oxidized pyruvate in the mitochondria and now we've produced acetyl coa so now that acetyl coa is going to enter into a cycle known as the krebs cycle now you may have heard it referred to as the citric acid cycle in biology back in high school maybe krebs is just named after the individual that described it now ultimately the fate of acetyl coa is going to depend on the availability of atp in the cell if there's not enough acetyl coa is going to head off to the krebs cycle but if there's enough atp the acetyl-coa is going to be diverted to fat synthesis for energy storage so remember how i mentioned before if we have excess sugar in our diet once all the glycogen stores have been stored up and maxed out then any of the excess glucose is going to be converted directly into fat now we're going to look a little bit later on at a process known as beta oxidation where your fatty acids can be broken down into two carbon pairs ultimately creating new acetyl-coa molecules so in that way our fatty acids then once acetyl-coa has been stored up in our fats we can also harness that energy storage to be able to feed directly into the krebs cycle now the krebs cycle uses a series of nine different chemical reactions whereby acetyl-coa is then bound to the oxaloacetate which is the four carbon byproduct of the krebs cycle to then form citrate which is our six carbon starting molecule of the entire cycle now citrate is also known as citric acid and that's where this cycle also gets its name from as i mentioned before it can be either referred to as the krebs cycle or the citric acid cycle and so the krebs cycle is this process by which this six carbon citrate molecule is then further oxidized while reducing our electron carriers and producing an atp molecule so that all of these electron carriers can ultimately be sent off to the electron transport chain for the production of atp and it's a cycle you start with one acetyl coa that's going to bind to the four carbon oxaloacetate which is going to form your six carbon citrate and then during this process two carbons are going to be removed and every time we remove a carbon in any of these cycles remember it'll bind to oxygen and be removed as carbon dioxide so you can see one here during this reduction reaction of the nad to form nadh and then further along from five carbon down to the four you can see where another carbon dioxide is given off at the same time we are then using those electrons to donate them to nadh which is being reduced during this process of going from the six carbon to the four carbon we have the phosphorylation of an adp molecule to produce an atp so let's think about numbers here we have one acetyl coa that's yielding one two three nadh molecules and it's yielding one fadh2 you remember i mentioned this is the other electron carrier that we see it comes into play a little bit later when we look at the electron transport chain so for now just understand there are two different electron carriers it's oxidized form it's known as fad and then once it's reduced add those two hydrogens with the two electrons it forms fadh2 now this four carbon molecule is then recycled you have the two redox reactions occurring and then finally this last form known as oxaloacetate then binds with another acetyl coa if there's a need for energy if the cell's requirements are being met by the level of atp in the cell well then acetyl-coa can be diverted to fat storage however if there's not enough atp then acetyl coa will continue to bind with the oxaloacetate which will then lead us into another cycle and remember this cycle that's illustrated for you here this is just a series of reactions that's taking place within the mitochondrial matrix okay so just just to recall here glycolysis is taking place outside and as soon as we're looking at pyruvate oxidation krebs cycle and even electron transport all of that's taking place within this region the inner region of the mitochondria known as the mitochondrial matrix all right so let's add them up here again we are in the mitochondrial matrix we've started with two acetyl coa six nad plus let's go back here to this diagram one two and three but remember it's the two acetyl coa all right so we double up all of our numbers so we've started with six nad plus and two fad molecules and then ultimately we're producing two atp six reduced nadh two reduced fadh2 and four co2 molecules so now we're going to move on to looking at the electron transport chain and this is where a lot of these end products specifically the electron carriers you're going to see all of them are going to act as our starting products for the electron transport chain outside of the mitochondria what was that chemical process taking place where we took glucose we created two atp as well as two nadh and two pyruvate molecules that was glycolysis and so remember we created pyruvate and in the presence of oxygen pyruvate is capable of then moving into the mitochondrial matrix where it can be oxidized to form acetyl coa now during this process we have nadh being produced that acetyl coa moves into the krebs cycle and through the krebs cycle we're producing six nadh two fadh2 and then four co2 molecules as well as those two molecules of atp so this is everything right here that we've covered thus far with all of the end products now remember in glycolysis we're producing two nadh molecules and the whole reason that we're reducing those nadh is to carry those electrons onto the electron transport chain why to produce atp so those nadh from glycolysis are going to have to pass in to the inner mitochondrial matrix and then they will also play a role in donating their electrons but they're a bit of an exception to a rule so we'll talk about those after we've talked about the rest of them so you'll notice here embedded within the inner mitochondrial membrane and to give you perspective this would be your outer mitochondrial membrane and the yellow would be marking your inner mitochondrial membrane okay so all of these protein complexes we're going to be talking about they are all located within the inner mitochondrial membrane now each of these protein complexes serves an important role in helping us be able to create a concentration gradient within the inter membrane space and we've talked about this before we're creating a high concentration gradient and we're continuing to pump these hydrogen ions into this space what type of transport mechanism must that be that would be your active transport mechanism specifically these are the proton pumps that we were talking about before these are membrane bound proteins that are acting as pumps to actively pump protons into this inter membrane space and we're getting close and you'll see why we're doing this in creating this concentration gradient so we have three of them and they can be identified here we're just numbering them protein complex one and if you want you can add in there in brackets proton pump one proton pump two proton pump three each of these has a unique role whereby it is going to be responsible for using the energy that's been stored up in these nadh and fadh2 molecules and using those electrons to activate the pump to send the hydrogen ions into the inter membrane space now nadh and fadh2 they operate differently let's start with nadh so nadh comes along and it is going to be oxidized again remember this is its reduced form it's carrying the electrons why is it carrying electrons well because we need to use that energy at some point where it's going to be really useful in producing atp here's how it works so your nadh molecule encounters the first proton pump nadh is oxidized back into nad it donates its electrons those electrons are going to then power the proton pump allowing it to pump that proton into the inter membrane space great you might be thinking so we've got one proton across now we need to go and get the other two proton pumps working so we have different coenzyme complexes this one is uh actually coq10 you've probably heard of is the more common name but it's known as ubiquinone and here's another complex known as cytochrome c all right what you need to know is that these are electron transporters and they are going to pick up the electrons from one proton pump and then transport them to the other proton pump and so in this case here with ubiquinone it's responsible for transporting the electrons from proton pump 1 to proton pump 2. all right so this is where we get into it's literally a chain of proton pumps that are transporting electrons what's the point to then pump those protons into that intermembrane space okay so nadh nadh drops off the electrons at proton pump 1.

[00:34:07]you get the proton sent across then ubiquinone then is going to pick up those electrons and it's going to transport them over to proton pump 2. well that's going to then activate proton pump two there you go you get your second proton across now cytochrome c is then gonna be responsible for picking up from proton pump two and transporting to proton pump three well now there you go we've activated proton pump three another proton is sent across now so look at that for nadh nadh started at one and those electrons activated proton pump one two and three so you had three protons that were pumped across for every nadh molecule all right that's important to remember now once these electrons end up here at the third proton pump we need to do something with them well we're able to use them in the addition to the oxygen that's present remember this is aerobic respiration along with the protons that exist in this mitochondrial matrix to create pure water all right so you may be thinking okay but we haven't produced any atp but we've fired a lot of protons into the inter membrane space so now that we've created this concentration gradient with the protons building up that concentration within the inter membrane space remember they're always going to want to find equilibrium so if you let them they're going to want to pass back into the mitochondrial matrix to be able to balance out the concentration between the two compartments well we actually have these specific membrane proteins that are known as atp synthase proteins and they're there to allow for a way for the protons to be able to pass back into the mitochondrial matrix and this passage of the protons moving from the inter membrane space back into the mitochondrial matrix is known as kidney osmosis i keep talking about the electron transport chain and how this is you know where you end up producing all the atp but the truth is it's the process of chemiosmosis where we actually produce all of the atp the rest of the electron transport chain is about building up that concentration of protons in the inter membrane space once they're allowed to then pass back through into the mitochondrial matrix we harness that movement and are able to then phosphorylate the adp molecules with phosphates to be able to produce our atp so this process here for producing atp is known as oxidative phosphorylation and this is different than substrate level phosphorylation you've seen this term i think already throughout and what this is referring to here substrate level is referring to the fact that by reducing or oxidizing the different molecules throughout the different cycles we are able to produce atp through those processes all right now because it's the transformation of one substrate or molecule to another it's referred to as substrate level phosphorylation okay and in contrast here at the atp synthase we have oxidative phosphorylation taking place and this is where we produce a bulk of the atp through our aerobic cellular respiration processes so now that we've been able to walk through the process from glycolysis pyruvate oxidation krebs cycle electron transport and chemiosmosis i recommend go and take a look at the video links that i've included in the youtube channel so that you can give yourself a visual to how dynamic this process is going to be especially the process here through the electron transport when you're actually able to visualize hey these electrons they're going to be carried by this ubiquinone over to number two and then cytochrome c will actually come and transport from two over to three it just it's helpful when you have the dynamic visual to be able to give you a better level of understanding now as i've told you the general rule is that for an nadh it's going to drop off its electrons at the first proton pump therefore it's going to pass through how many three so for every nadh we are going to produce three atp molecules all right now with the fadh2 they drop off directly at ubiquinone and ubiquinone picks it up and takes it directly to two all right so because we're not starting at one and starting at two instead then there's only going to be two atp that are produced because we're going to have electrons sending across from the second pump and then from the third pump so for every nadh it produces three atp and every fadh2 molecule produces two atp now you're looking over here thinking ah remember this nadh that was produced in glycolysis well actually two from every glucose what happened to them well something a little bit different doesn't follow that rule the nadh from glycolysis they actually you can see here they bypass that first proton pump and so they act similar to fadh2 whereby their electrons are given directly to ubiquinone and then ubiquinone takes them to proton pump 2.

[00:39:42]so for the 2 nadh that are produced during glycolysis they are only going to yield 2 atp each as a general rule of thumb the nadh molecules produced through pyruvate oxidation krebs cycle they are going to be producing 3 atp the nadh from glycolysis is only going to produce 2 atp per molecule and so if you work out the math you'll see that we had 2 nadh here 2 nadh here and then 6 here so it's 1080h and 2fadh2 for a total of 32 atp all right so let's take a look at our chart here for our final portion we're looking at the electron transport chain remember taking place within the mitochondria but now the three proton pumps as well as the atp synthase are all embedded within the inner mitochondrial membrane now our starting products we had 10 nadh now i've broken this up so that you can include this in your chart where you have eight that are coming from pyruvate oxidation as well as krebs cycle and then you have the two nadh that were coming from glycolysis we also have two fadh2 as well as the oxygen needed to be able to produce the water as the end product as well as the oxygen that is capable of receiving those electrons at the very end of the electron transport chain and producing water all right so that gives us our end products of water as well as the 32 atp so i think you can appreciate by now if all you were utilizing was the process of glycolysis to be able to produce two net atp from one glucose molecule you're going to be working pretty hard and then you can compare that to our capabilities of being able to produce 38 atp from one single glucose molecule because of aerobic respiration and there we go so if you're feeling tired it could be that you are lacking in a number of the key uh vitamins that are responsible for the production of certain key players in this whole process so for example here if you just take a look a number of the b vitamins are responsible for producing different intermediates as well as the electron carriers that are so key and responsible for carrying electrons from the krebs cycle to the electron transport chain as well coenzyme q also known as coenzyme q10 coq10 you may have heard of that so that is your ubiquinone as well your omega-3 fatty acids because remember all of the electron transport chain is taking place within the inner mitochondrial membrane and we focused a lot today on looking at glucose and how glucose can then be utilized to produce these 38 atp per molecule but we know we can also utilize all of our other macromolecules specifically the monomers to be able to then break those down further and metabolize them to be able to make atp as well okay so quick review we have our four different classes of macromolecules each of those is made up of their individual monomers we have our polysaccharides our carbohydrates our proteins our fats as well as our nucleic acids and remember each of those macromolecules are made up of the individual monomers so we have glucose that we focused on today the amino acids we're going to take a look at as well as fatty acids and how we can utilize those to be able to also produce atp and then as well i know we've talked about how nucleic acids don't provide us with a lot of caloric value which is why they're not included on the nutrition labels but there are pathways through which we are capable of breaking down nucleotides further it's just the least advantageous route for atp production all right and so this is the mechanism by which we can enter into any of these different stages here using these different macromolecules so today we focused on how a glucose can be fed through glycolysis pyruvate oxidation into the krebs cycle and then finally all of those electron carriers donating to the electron transport chain to produce atp now the second line as soon as you've kind of used up all the glucose stores that your body will start to burn fat and so you can take your triglycerides and break them up into glycerol molecules as well as your fatty acids now the glycerol is capable of feeding into glycolysis directly and then being able to pass through the entire process and then with the fatty acids we're able to take those carbon hydrogen bonds within the long chains of fatty acids and break them up into pairs and each of those two are used to make your acetyl coa all right so remember how acetyl coa was the two carbon byproduct from pyruvate oxidation well if you take two carbons from your fatty acids and then you add on a coenzyme a to that process known as beta oxidation then we're able to create acetyl coa which can then feed into the krebs cycle so you can see here really all you're missing out in terms of atp production is the two atp from glycolysis beta oxidation is definitely an advantageous route for us to be able to produce atp from another macromolecule and then our third line this is one of the least advantageous routes would be breaking down amino acids so it goes through a process of deamination we are able to be able to convert into different intermediates that can enter at multiple pathways throughout different cycles the biggest problem with breaking down proteins is that we end up producing nitrogenous wastes okay i'm hoping you recall i made a big deal about this we talked about how proteins and nucleic acids both contain nitrogen in them right so at the end of the day when we're breaking down your glucose what do we end up with co2 that we breathe out and water right it's a clean burn same thing with your fatty acids when we're looking at proteins nucleic acids we have this leftover nitrogen and we've got to get rid of it somehow and so what we do is we convert that into ammonia so nh3 now ammonia can't just circulate from our liver once that ammonia has been produced we then need to convert it directly into a product known as urea and urea is capable of then being transported through our blood eventually being filtered out in the kidneys where we can then excrete it from our bodies through urination but we have to get rid of it and so that's one of the negative side effects of having to break down proteins as well as nucleic acids is that the nitrogenous waste has to be dealt with now if you think of somebody who's entering into starvation mode well the first thing the body's going to do is tackle those glycogen reserves and get rid of all the glucose stores the next thing that the body is going to do is start to break down all the fats now as soon as that happens then the body is going to start to target the protein so think about this you have proteins everywhere one of the places you're going to see this where the body's breaking down its own proteins is in muscle wasting that's going to occur so that's why typically when an individual enters into that mode essentially where the body is just grasping at straws trying to find energy from any source you start to see the real you know muscle wasting occurring because the body now starts breaking down its own proteins so hopefully this gives you a really good picture for how our body sources and you know deals with the sugar that we take in helps store it convert it to fat but we now know hey that's great because we can also then burn that fat later on all right so atp yields one nadh molecule will yield about 3 atp what was the exception the nadh molecules from glycolysis right they will yield 2 atp so approximately from every glucose molecule we are producing 38 atp molecules right 32 from oxidative phosphorylation two from the krebs cycle and another two from glycolysis so if you take this ratio that you're making from a six carbon glucose molecule making about 38 atp how many atp molecules would we make from one fatty acid that was made up of 18 carbons what do you think it works out to approximately 114 atp molecules all right so we focused on aerobic respiration for pretty much all of this lecture today now some organisms live in anaerobic environments where they lack oxygen organisms like bacteria simply do not have the luxury of being able to utilize oxygen because they do not have membrane-bound organelles all right so in the absence of being able to use oxygen to be able to harvest that full yield from aerobic respiration we have to rely exclusively on glycolysis to produce the atp right so remember with glycolysis we are only going to be netting 2 atp and then we're also going to be reducing those 2 nad plus to produce 2 reduced nadh now if we just kept going through this process and we had nowhere for these nadh to then be further oxidized again we'd be stuck and so a anaerobic respiration is a process by which where the anaerobic bacteria are capable through a process known as fermentation to then have those hydrogen atoms as well as electrons from the nadh molecule be donated again to organic molecules to then regenerate that nad plus this process of two pyruvate being converted to two acetyl aldehyde one of the carbons then is given off in the form of co2 and so this allows for the continuous recycling of nad plus and this is the key point here we're able to produce pyruvate through the process of glycolysis but then able to convert that into an organic molecule acetyl aldehyde which can then become reduced itself as it oxidizes nad all right so if we're reducing this we're giving the hydrogens and giving the electrons to that molecule to produce ethanol all right so what we're doing is recycling the nad to allow this process to continue right well this process of fermentation this is how all alcohol is made this is how beer is made so example here with yeast which are a unicellular fungi remember that exception to the fungi kingdom they're typically eukaryotic multicellular yeast are unicellular in this case pyruvate is converted into acetyl aldehyde which then accepts that hydrogen from the nadh producing the oxidized nad plus and ethanol now in animals it's a little bit different in terms of the byproduct we're able to in anaerobic conditions be able to convert that pyruvate directly into lactate which is also known as lactic acid and this is what occurs within our muscle cells okay this is the burning sensation that you feel if you've been working out and you're working in a situation where you have an oxygen debt as we run out of oxygen and we don't have enough to make atp through aerobic methods then we are going to be relying on glycolysis to be able to produce that atp and then the byproduct is going to be that lactic acid buildup in our muscles now anaerobic respiration is actually used to ferment lots of different foods all the way from yogurt soy sauce sauerkraut kimchi you name it so we talked a little bit at the beginning about your basal metabolic rate which just think of that as sort of you wake up in the morning your eyes are open you really haven't done anything you're not moving you're not eating you're not exercising okay your metabolic rate at that point that would be your basal metabolic rate so that's just the rate at which your body is going to use any of the energy stores in order to produce atp for just your body to survive now there's a number of things that we can do to increase our total metabolic rate and one of the big ones is exercise right you're increasing the demand that your body is going to have for energy to be able to produce all of those muscle contractions exercise is also going to cause growth hormone production from the anterior pituitary gland as you're stimulating those muscles and you're putting demands on those muscles and now the more muscle that you're building the more muscle cells that you have they are going to require the most energy just to function and so the more muscle that you have the more atp that's going to be required just at a basal rate the more muscle that you build actually does pay dividends because it's going to be working for you when you're not working essentially all right so having more muscle than fat also increases atp requirements exercise also stimulates thyroid hormone production remember thyroid hormones are your metabolic hormones so if you have elevated levels of thyroid your metabolic rate is also going to be increased now another way you can help to lose weight is just decreasing the calories that you're taking in one of the most important things is to watch the amount of sugar that you're taking in lots of sugar is bad for so many reasons you know not only is it just going to be converted into fat if you have excess stores of it but it's also pro-inflammatory lots of different conditions that occur with the body are a result of just high levels of sugar in our day to day diet now minimizing starchy carbs to about two to three servings a day and it's best to eat those after you exercise because then it's an easy fuel source so when your body is wanting to repair the muscle tissue after your workout it has an easy fuel source that's readily accessible for your body now lastly incorporating fasting into your weekly routine i'm not going to hold you to any specific guidelines but i want to be able to introduce you to some of the ideas behind why you would fast number one it forces your cells to use stored fat so think about this if you continue just to give your body glucose all the time it's just going to keep up storing the excesses glycogen and then if you try to you know watch what you're eating your body's first gonna have to break down all of that glycogen before it thinks yeah now i'm gonna go to those fat stores to go and produce energy so by fasting you're forcing your body to have to eliminate those glycogen stores and then it has to then start to target the fat to start burning that also when not exercising fasting can help to increase growth hormone as well alright so when exercising you need to make sure you have adequate fuel but when not to go through a period of fasting can help to also stimulate uh growth hormone and then also decreases insulin resistance so we're gonna get to talking about insulin and the role that it plays in helping manage your blood sugar levels we'll do that when we look at the endocrine system next semester but ultimately diabetes specifically type 2 diabetes is caused because your cells have become resistant to insulin and typically that's due to the bad fats in our diet and so the cells are resistant to insulin insulin can't bind to the receptors and can no longer then allow for the glucose to be taken into the cells as readily all right well hopefully that was some food for thought that brings us to the end of this lecture but more importantly to the end of the new material that will be on your midterm exam now if you have questions in the meantime feel free as always to send me an email and get back to you as soon as possible otherwise i look forward to seeing you during our tutorial take care