Metabolism Overview

this is the chapter on metabolism and just remember metabolism is what happens after the nutrients are absorbed what happens to those so we&#39;re going to have to worry about is this uh component stored can what does this component used for is it used for ATP production if it is used for ATP production how do we get it into that Machinery used to make ATP so that&#39;s a large portion of what we&#39;ll be worrying about in this chapter is basically how ATP gets produced so let&#39;s talk about carbohydrates at first so most of the carbohydrates we get come from plants we do get lactose from dairy products and so the monosaccharides which we&#39;ll have to deal with uh are going to be glucose fructose and galactose those are the ones which uh we absorb from the diet there are a number of disaccharides out there sucrose which is normal table sugar maltose which is two glucose molecules stuck together and uh lactose or uh the milk or the sugar found in milk excuse me polysaccharides are the bigger complex uh carbohydrates as include starches uh from plant sources glycogen from uh animal sources both starch and glycogen are polymers of glucose they are slightly different in how the glucose molecules are put together and uh you know give have uh starching glycogen have different uh chemical properties due to the way that those glucose molecules are put together uh cellulose is another form of glucose cellulose is made by plants as a structural component and we are incapable of digestion of cellulose I.E it&#39;s this wood product this is basically dietary fiber in a lot of cases and so the disaccharides and polysaccharides that we ingest are basically converted to glucose uh through the digestive process in the metabolism of the liver and then we&#39;re either going to use that um glucose for energy util and turn it in well you use the glucose to turn it into ATP or we&#39;re going to store it either as glycogen or we can convert that glucose into fat molecules into fatty acids and then store that as a triglyceride so what do we need carbohydrates for well we use them as um well a sources to get ATP uh any excess glucose which is coming in uh during uh a phase when you&#39;ve just eaten that will be converted into glycogen glycogen can be stored in the liver uh skeletal muscle cells also store glycogen any excess once uh all the glycogen stores are filled up we can uh send that glucose into our Ayes and our Ayes can turn that into triglycerides and Stor as fat uh we also have to uh use uh carbohydrates to make DNA RNA ATP has a uh carbohydrate component to it and uh many lipids and proteins have extensive uh carbohydrates attached to them and so we&#39;ll have to use um these incoming carbohydrates to make some of the specialized uh carbohydrates that we put out on glycoproteins and on the glycol lipids so lipids right about um 95% of all the triglycerides coming in get used for uh utilization as ATP uh we turn components of those lipids into ATP or they get stored directly in the adapost tissue and the liver now there are a large number of triglycerides coming in there the saturated uh fatty acids right uh and so um these guys have no double Bonds in their fatty acids and these guys are found in basically um uh in uh you know animal sources whole milk uh cheese and eggs these are all animal sources of uh triglycerides unsaturated fats and oils there are double bonds between these guys so monosaturated have one double bond this is um found in olive oil and uh peanut oil polyunsaturated fats have more than one double bond these are found in fish and in sunflower oil uh the and uh typically the saturated fats are worse for us than the unsaturated fats and trans fats are um processed polyunsaturated fats but the problem here is it&#39;s the arrangement of that double bond um and across that double bond and uh Transat FS tend to while they are unsaturated do tend to be bad for us because they increase uh HDL levels and so if you avoid the trans fats you&#39;re probably much better off and just stick with the naturally occurring uh unsaturated fats so cholesterol is found in the diet but again we make most of it uh we use cholesterol in our membranes we also use it for uh lots of hormones um right all the um hormones like testosterone estrogen progesterone aldosterone and a number of mineral corticoids Are all cholesterol-based uh components but cholesterol is not found in plants uh fossil lipids uh for example like gphin these are components of plasma membranes and we can get uh some of this material from egg yolks so uses of lipids that we need physiologically so we can turn components of lipids and generate a lot of ATP from them we will store triglycerides as an energy source in the adapost tissue and also in the liver the cholesterol which we are eating or basically U make we need those for bios salts we need those for uh all of our cellular membranes and all of the steroid based hormones uh estrogen progesterone testosterone aldosterone these are all uh cholesterol based steroid hormones we have the acoid these are derivatives of fatty acids these are uh signaling components of the inflammatory process they&#39;re also involved in blood clotting tissue repair and the contraction of some smooth muscles uh phospholipids such as lethin these are important components of the cell membranes uh and we use them to make the myin sheaths they also form part of the bile so we use um you know lipids in a lot of different ways so proteins are basically long chains of amino acids and so we can break the amino acids down into those which are considered essential so uh essential amino acid is one which is not made by the humans we can&#39;t make them so we are dependent upon them to come in from the diet so histadine isoline Lucine lysine methionine poly uhen alanine threonine tryptophane and valine they all have to come in from the diet uh conditionally essential right there are some conditions under which we are not able to make a certain number of amino acids right this is um you know if there are premature birth or certain metabolic problems right we can&#39;t make Arginine cysteine glutamine glycine Proline and or tyrosine now there are some some amino acids we could consider they&#39;re non-essential in the diet basically because if we get the essentials uh coming in we can make uh things like alanine aspartic acid aspargine uh Seine and glutamic acid but you know we&#39;ve just listed basically all the 20 amino acids which are normally found as components of most of our uh proteins in the body so protein sources for the if it&#39;s considered a complete protein Source basically all the essentials are in there so meat fish poultry eggs cheese um things like that uh are considered complete proteins incomplete proteins uh are missing some of the essential um amino acids but combination of incomplete proteins can give you a meal with all the essential amino acids in it and so you know um vegetarian and vegans do have to pay a little bit more attention to what they&#39;re eating to make sure that they get proper nutrition but you can be totally healthy and have a vegetarian or vegan diet uh conversely to that if you are a vegetarian or vegan that doesn&#39;t mean your diet necessarily has to be healthy right um you could be a vegetarian and still eat dairy products and eat nothing but milkshakes and chocolate chip cookies that would not be a very healthy diet but it would still be vegetarian so uh functions of proteins right proteins do a lot for us right so antibodies are proteins that have a protective function uh enzymes and hormones many of these components uh are uh protein in nature uh proteins form all have lots of structural components and uses in the body collagen all the basement membrane proteins uh muscle contraction and cytoskeletal elements are proteins and transportation right hemoglobin ion channels various uh membrane proteins which allow uh facilitate diffusion those are all proteins and Incredibly incredibly important so we also have to talk about vitamins right we often associate vitamins with good health but these are organic molecules which have to come in from the diet because we cannot uh make these things on our own so there are essential uh vitamins which must be obtained from the diet much like the essential amino acids and there are compounds which we have to take in which are considered provitamins which we are capable of converting into uh vitamins and so these include things like uh beta carotene uh seven dehydr cholesterol and tryptophane now vitamins are components which are required uh as co-enzymes these are uh co-actors which help the enzymes do their job and in a lot of cases the enzymes are inactive unless these co-actors are around and so um you know we need them they&#39;re readily available from the environment in most cases and so they&#39;re so readily a available that we don&#39;t need to make them we get them from well the things that we actually consume so look at some of the vitamins right so we&#39;ve got the fat soluble vitamins including vitamins a d b e and K now the fat soluble vitamins we can store in fat uh storage areas uh of the body and if we take in too many of these vitamins we can actually get to a level where some of these vitamins can become toxic uh high levels of vitamin A can actually cause bone and muscle pain uh skin disorders hair loss and cause the liver to get larger too much vitamin D can cause um too much calcium to be coming into the bodies and that calcium is going to start dropping out of solution in kidneys heart blood uh and in blood vessels so you know too much of anything is not good for you and too many of these vitamins can be bad for you uh water Sol water soluble vitamins excuse me include the B uh range of vitamins and vitamin C um these guys are water soluble and if these are present in the diet in excess they are normally excreted from the body uh uh quite quickly um mostly through loss of through the urine uh high levels of vitamin C can actually cause an inflammation condition in the stomach and can lead to diarrhea and so you know again too much of something is not necessarily good for you we need a number of minerals coming in uh from the diet right these are inorganic compounds like sodium and calcium magnesium things like that we need these to maintain uh normal homeostasis right if it&#39;s a major mineral by definition we need 100 milligrams or more on a daily basis trace minerals less than 100 mix and so you know we need uh sodium pottassium chloride uh phosphate things like that um to you know for resting membrane potentials we need the resting membrane potentials for Action po Potentials in our nerves and in our muscles um we need calcium for our bones and our teeth um buffering system throughout the body phosphate um bicarbonate things like that uh you know we we need a lot of minerals and so we can get these from Plants Andor mineral uh and plant or animal sources excuse me uh but uh the minerals which are coming in on plant fibers are sometimes a little bit hard to absorb uh you know calcium can be hard to absorb trace minerals also includes things like copper and zinc ion uh or iron excuse me we we need all of these compounds uh in you know the right goldilock zone for proper health so let&#39;s just start looking at metabolism and just getting a groundwork in some of the terminology that&#39;s used and so when we talk about metabolism in a physiology setting right we&#39;re talking about all and every chemical reaction which can occur in the body and so we&#39;re not just talking you know about you know someone has an easy time of losing weight because they have a fast metabolism or I keep putting weight on because I have a slow metabolism no metabolism in this course will be referring to Every chemical reaction that can happen in the body and we can divide these reactions up into either catabolic or anabolic reactions so in a catabolic reaction we are releasing energy and we are breaking a larger molecules uh down into smaller uh molecules uh for anabolism we are requiring energy and we&#39;re Pi taking smaller molecules and forming larger ones and so um you know an anabolic steroid is a steroid hormone which causes muscle to be formed so we&#39;re making muscle so uh this is the way I remember that anabolism is making a compound catabolism is breaking it down and um so we get energy from nutrients most of that energy is converted into ATP and then ATP is the currency in which uh energetic reactions are basically powered throughout the body and drives all of these anabolic reactions so as an example of catabolic and anabolic reactions we&#39;re looking at the formation and the utilization of ATP so ATP is this molecule shown here it&#39;s got a ribo sugar it&#39;s got a nucleotid like portion to it an adenosine and it&#39;s got three phosphate groups attached to it now in an anabolic type of situation we&#39;re using the energy from ATP contained in ATP and basically it&#39;s most of that energy that&#39;s utilizable physiologically is in the bond between the second and the third phosphate group those little uh yellow um circles with the p in it that&#39;s a phosphate group and so when that energy is utilized that phosphate that terminal phosphate group is detached and quite often then reattached to the molecule which now needs that energy so that&#39;s considered an anabolic reaction because we&#39;re using that energy to drive the formation of some larger molecule now for catabolism we will actually you release energy from some compound that we&#39;ve taken in from the diet and we&#39;ll actually remake this ATP molecule so what we have to do there is we have to take this ADP this diphosphate molecule and reattach this phosphate group to it to increase the energy of ADP to the level of energy that&#39;s in an ATP so that that ATP molecule can be reused again and so um you know we&#39;re constantly generating ATP we&#39;re constantly using that ATP and and uh need a steady supply of nutrients to drive the production of ATP and we&#39;ll start getting into how the body actually generates ATP from carbohydrates proteins and fat sources later on in this video so if we look at overall how we generate ATP so on the left hand side here we can see we&#39;ve got lipids here in this yellow we&#39;ve got carbohydrates shown in blue and protein shown in uh the red um section of that graphic so what we&#39;re going to do first is look at basically in great detail how we take carbohydrates run it through this glycolysis process run it through this citric acid cycle and then through um this uh bottom which is going to be the electron transport chain and chemo osmosis now what we can see is is that basically this process works uh quite well for glucose coming into this process because we have to remember that any monosaccharide coming in which isn&#39;t glucose uh from the small intestines will be converted by the liver into glucose and either utilized or stored so we&#39;re really talking about glucose metabolism here here now for lipids we can see that we can convert triglycerides and other lipids into components which we can feed into this Central carbohydrate mechanism likewise we can take proteins break them down into component into individual amino acids and then those amino acids can be fed into this basic pathway for carbohydrates and so what the next step is going to be is we&#39;re going to be be looking at the how we break down uh glucose and turn glucose into ATP and at that point once we understand that process we can see how the breakdown components from lipids and the breakdown components of amino acids can also be fed into this uh metabolic machine for making ATP so carbohydrate metabolism so monosaccharides get broken down from the complex carbohydrates our livers will convert any non-glucose monosaccharides into glucose and that glucose will be utilized to generate ATP will be stored as glycogen or uh once the glycogen stores are fulled we can convert that glucose into lipids and then store that energy in that glucose in the form of lipids actually so the first step in breaking down glucose is a process known as glycolysis and so if we break this word down gluco here is referring to glucose Lis means breaking so we&#39;re breaking down glucose and at the end of the process of um glycolysis we will form two molecules of what is known as pyruvate or pyruvic acid and so there&#39;s a couple major steps in all of this U right but at the end of glycolysis we get four atps we get two molecules of this nadh stuff and two pyruvate molecules and all of these things are going to be important as we&#39;ll see now if we go and look at these major steps so glucose comes into a cell we have to transport that glucose into a cell and one of the first things that happens is we use an ATP molecule to transfer that phosphate group from the ATP to the glucose molecule which is a little bit odd when you think about it because glycolysis is the first step in making ATP right this is how we turn glucose into into ATP and the first step uses an ATP molecule we&#39;re actually in an ATP deficit right now because we&#39;ve not turned that glucose molecule into any ATP yet all we&#39;ve done is use an ATP to attach that phosphate to the glucose but overall we should just know that this is a phosphorilation process um what happens next is well we actually use another ATP at this point we have a molecule known as fructose 16 bisphosphate bis phosphate is referring to the fact that there&#39;s now two glucos two uh phosphates on it excuse me and they are in the one position and the sixth position of the fructose molecule now this is still the fructose molecule is a six carbon molecule glucose is a six carbon molecule that&#39;s important to know what&#39;s important to know about pyruvate is pyruvate is a three carbon molecule so what happens here is we take the fructose 16 by phosphate and we turned it into well two molecules which each have three carbons a piece so we take a six carbon molecule turn it into a three carbon molecule and another three carbon molecule in this process we make nadh which is going to be a molecule which we run into later which carries electrons around the system and that&#39;s important uh as we&#39;ll see and we got ATP out of this process overall we get a net generation of ATP and we get pyate generated so important things to know some of the energy in that glucose molecule gets turned into ATP some of the energy from that glucose mole Ule is transferred into this nadh thing and the rest of that energy from that py is from that ATP is in the pyate molecule and some of that energy is just lost as heat that&#39;s heat loss is just due to thermodynamics we can&#39;t get around that that&#39;s just the way the in the um Universe works now notice glycolysis makes four ATP molecules but it uses two ATP molecules so of those four ATP molecules which get generated the first two just basically are there to replace the two that we used to generate those four so at the end of the day each glucose molecule which enters glycolysis with will make a net of 2 ATP overall it makes four but we had to use two of those to basically energize the glucose molecule to prime the pump so to speak to get that energy out from that glucose molecule so we only get a net gain of two in spite of the fact that we&#39;ve made four of these things right so the way to think about this is you know if you were to hand hand me um $2 and I handed you $4 right you would go oh this is a good thing right it you know I&#39;m $2 down right but at the end of The Exchange I actually have $4 in my pocket when I only started out with $2 in my pocket right so you know you reach in your pocket there&#39;s only $2 in there you hand them to me and I hand you $4 and you put them in your pocket and you now go ooh I have $2 more dollars at the start at the end of this process than when I started out and then you go can I do this again please right and so we are generating ATP from glycolysis it costs us 2 atps but that&#39;s okay because we get a net gain of 2 atps at the end of the day because we&#39; made four total atps in glycolysis so let&#39;s look at this in some excruciating detail so at the top here we can see a glucose molecule now that glucose molecule is brought into the cell transported across the membrane and one of the first things that happens is we burn an ATP and we attach that phosphate group to the sixth position the six carbon and so now we have a molecule of glucose 6 phosphate that rearranges itself into a fructose 6 phosphate molecule and we burn another ATP this ATP is now attached to the one position so we get a molecule of if I can find my pointer fructose 16 bis phosphate we right we&#39;ve got a phosphate here and a phosphate group here on this five carbon sugar this fructose molecule actually it&#39;s a six carbon uh molecule the Rings only five excuse me now this is where we&#39;ve used those first two atps now this is a six-carbon molecule it gets broken up into those two three-carbon molecules um one of them is a glycer aldhy 3 uh phosphate this molecule here on the right the other one is a dihydroxy acetone uh phosphate molecule over here but this molecule on the left gets converted into the glycer aldhy 3 phosphate so basically the way to think about this is we&#39;re just making two copies of this molecule and then this molecule so we&#39;ve taken a glucose molecule a six carbon molecule brought it into the cell phosphorated it I.E transferred that phosphate group uh that converts itself into that fructose 6 phosphate we attach another phosphate group to it again burning another ATP to get the fructose 16 bisphosphate and that breaks up into those two three carbon molecules right and so that&#39;s glucose up well as far as we&#39;ve gotten on this slide so let&#39;s go to the next slide so we&#39;ve got that well basically two copies of the glycer alide 3 phosphate and we bring in two molecules one for each of the glycer alide three phosphates of an nad+ and we turn that into an nadh this is going to be important because that nadh is a carrier of that electron and some of the energy from that glucose molecule is in that uh nadh molecule so at this point we can bring in an a DP molecule one each for every of the glycer alide 3es and remember we&#39;ve got two of those glycer alide 3s and we get our first two ATP molecules made we then go through a couple other steps and we bring in two more adps and we get two more atps and a pyruvate molecule at the end of the of all this so bring the glucose molecule in burn an ATP burn another ATP we now split that six carbon molecule into two three carbon molecules each one of those three carbon molecules has a phosphate group on it and we can transfer that phosphate around and basically convert 2 a two adps into into two atps and then we can convert another 2 ad DPS into two atps at the end of glycolysis and end up with the pyruvate molecule so when glucose enters we get a net gain of two atps we get two pyate molecules and we get two molecules of the nadh at the end of glycolysis that&#39;s what we that&#39;s really what I want you to know about glycolysis for all of these metabolic reactions I don&#39;t expect you guys to memorize the structures of all these compounds I don&#39;t want you to memorize each and every step but I want you to know the overall process glycolysis starts with glucose we use two atps we get four atps out of glycolysis overall but since we burn two atps the net gain from glycolysis for atps is only two but we do get two pyruvates and two nadh molecules and we get those nadhs from the nadh plus molecule which is going to be important in a minute and remember that some of the energy from that glucose is in that nadh and some of it is also in the um pyruvate and certainly some of it is in the 28 the net a two atps that we produced so if we look at the overall ATP production from one glucose molecule right we got well two atps overall we got well some energy is in those two nadhs and in those pyrates so those are the those other products and there still energy in there then everything else on this chart we haven&#39;t talked about in any detail at all except just letting you know that these things exist right so when we make this compound acetyl COA shown here right we get two more adps here um when we get into the citric acid cycle here we generate two atps and we get six more nadh&#39;s and two molecules of an fad H2 which has a very similar um role as the nadh molecules now in the electron transport chain we make 28 atps in a very mysterious way which we&#39;ll get into in the next video and we also make some water molecules now at the end of the day in theory from a single glucose molecule we can make 32 atps two from glycolysis two from from the citric acid cycle that gets us four and then another 28 from the electron transport chain and so we drive the electron transport chain using well the energy in the nadh&#39;s and the fadh2s we&#39;ll see that in the next video but and that 32 atps from a single glucose that&#39;s the theoretical maximum sometimes there&#39;s a little bit of inefficiency Sometimes some of the membranes are a little bit leakier than what they need to be as we&#39;ll see for the electron transport chain and so sometimes we will&#39;ll only get 28 sometimes we&#39;ll get 30 but anywhere from 28 to 32 ATP molecules are generated on average from a single glucose molecule which starts this process all right so we now have to deal with the roles of oxygen in uh metabolism so that brings up aerobic and anerobic respiration up first is Anor robic this means we can break down glucose to get ATP with no oxygen in absence of oxygen molecules we can do this now if there&#39;s no Oxygen present during glycolysis we have to take the pyruvates that are made and generate lact lactate or lactic acid molecules from that um we do that because we need to regenerate those nadh molecules those NAD plus molecules I should say those nadh plus molecules get turned into the nadh molecules if we don&#39;t have nad+ molecules the glycolysis process stops and so in order to get nadh I&#39;m sorry to get nad+ molecules back we have to turn the nadh molecules back into NAD pluses and to do that by doing that we can basically take that nadh take that hydrogen off that H part put it onto the pyruvate molecule to make the lactate molecule by doing that we regenerate the NAD plus so that glycolysis can keep on moving in spite of the fact that there&#39;s no Oxygen around basically this has to happen because oxygen is required for pyruvate&#39;s next couple of steps now if if oxygen becomes available at some later point we can convert that lactate back into U pyruvate or back into glucose by the Corey cycle uh and um we can get some of that energy back because some of that energy from the glucose molecule is still now in that lactate so anerobic respiration as we&#39;ll see we can break down uh glucose with no o oxygen around we get U two molecules of lactate and two molecules of ATP so this is with no oxygen around right so this is um you know what happens in our cells when uh particular our muscle cells when they become short on oxygen just due to the fact that we&#39;re you know really uh Contracting that muscle using a lot of ATP and our cardiovascular system is just not in uh capable of getting enough at ATP or enough oxygen in there to generate enough ATP and we can do this for a short amount of time in some of our uh anob muscles and so if we look at this in uh this Anor robic uh respiration so we have glucose here it goes through glycolysis uh shown here as number one we get our two pyate molecules but um we have to uh regenerate those NAD pluses so remember we get those two nadhs from as byproducts from turning the glucose into pyate but we now have to take those nadhs use them to convert the two pyrates into the two lactate molecules that regenerates the in a d plus molecules which will allow the next glucose molecule to be turned into two Pates and uh eventually into the two lactates right but we are still in that process generating two atps so we can still generate ATP in the absence of oxygen using this process as you&#39;ll find out when you go through your um microbio biology classes a lot of microbes uh can generate atps live quite nicely with no oxygen whatsoever U this is how botulism toxin can survive in improperly canned goods for a very long time and cause problems for humans when they eat that food because botulism toxin is really really nasty and um the botulism bacteria can grow quite nicely in that nice sealed jar because it doesn&#39;t need any oxygen and has lots of things to chew on uh because well you&#39;ve preserving food sources uh in that jar and um yeah Anor robic uh bacteria uh can are nasty little buggers from a health standpoint so in contrast to that is what happens when there&#39;s oxygen around in aerobic respiration so um we can break down the glucose with oxygen around to make carbon dioxide water and eventually 32 molecules of ATP but that isn&#39;t going to include what we get from glycolysis and then the subsequent breakdown of that pyate through the um citric acid cycle and the um electron transport chain now most of the ATP which we generate comes from having oxygen around and so we have to go through glycolysis we then have to form this acetal COA compound we then run molecules breakdown products of that pyro pyate excuse me through the citric acid cycle we will get some atps directly from the citric acid cycle but in the electron transport chain we will use the nadhs and the fadh2 molecules generated from glycolysis acetal COA formation and the citric acid cycle we will use the energy in those molecules to make 28 out of those 32 atps in the electron transport chain so we&#39;ve got aerobic respiration in uh well generalized here so we&#39;ve got glycolysis right we take glucose we make two py two pyate molecules we get a Net G gain of two atps and we get two nadhs we then take those pyrates and we turn them into acetal coaz that generates uh nadhs and we still have some of that energy in that acetyl COA that acetyl COA molecule is fed into this citric acid cycle which we&#39;ll go into detail in a little bit from that we get well some CO2 molecules we got some six nadh&#39;s we get two molecules of fadh2 and we actually generate two molecules of ATP for every glucose molecule which starts through this process I.E the glycolysis process the electron transport chain will use all of the nadhs and the fadh2s that are generating to make well those 28 out of the 32 atps now this is where oxygen is really required and that oxygen will combine with some protons to basically form water molecules and uh we do create water as a byproduct of aerobic respiration so let&#39;s look at some detail on how the pyate which we get from glycolysis gets converted into acetal COA in this process we do release a carbon dioxide molecule now this happens in the mitochondria those little tiny organel which everyone remembers as the PowerHouse of the cells now there is an nadh molecule made during this process so let&#39;s take a look at that then we have to run everything through the kreb cycle uh we get basically a production of citric acid because at that point we have an oxil acidic acid which is part of that cycle and this incoming acetal COA they get together and make a citric acid molecule hence the Centric acid cycle name we then run through a series of reactions with the Centric acid molecule at the end of the day for every turn of this citric acid cycle we get an ATP molecules made we get nadh molecules we get fadh2s we get carbon dioxide and we get that oxal AIC acid back and since we have an oxal AIC acid back we can cycle around again uh for uh well when we generate another acetyl COA uh from well the pyate molecule so the pyate molecule is shown here it&#39;s a nice three carbon molecule it&#39;s in the cytool it moves from the cytoplasm the cytool basically into the mitochondria and the mitochondria has an inner membrane space uh within its own uh membrane and the Matrix uh is has an inter mitochondrial membrane in it so we take that pyate we basically which remember is a three carbon molecule we remove a carbon and that carbon leaves as a CO2 molecule now in that process we take one of these nadh I&#39;m sorry NAD pluses and turn it into an nadh so some of the energy from that pyate has been transferred to that nad+ and becomes an nadh basically because we moved an electron onto it and then we get what&#39;s known as an acetal group an acetal group is a two carbon group and this acetal group is a um important molecule in the metabol in a lot of metabolic pathways as we&#39;ll see and so uh just remember that the acetal group is a two carbon molecule and has uh it&#39;s a major crossroads uh in metabolism in that we can use this acetal group to feed into the citric acid cycle we could use this acetal group to make fats if we needed to or to make carbohydrates if we needed to this acetal group if it&#39;s moving forward into the citric acid cycle gets hooked up with what&#39;s known as co-enzyme a and then with once that uh twocc carbon group attaches to the co-enzyme a we get an acetal Co an acetal COA and so this Cycles around all the time Co COA will uh get together with this acetal group to form the acetal COA and then that acetal COA will get fed into the citric acid cycle so here you can see the citric acid cycle in all of its Glory so we have the acetal COA coming in from the top here and it gets together with oxil atic acid which is this four carbon molecule right here and so that gets together and forms citric acid which is the namesake for this entire cyclical process now this becomes isocitric acid and then at this point we have an NAD plus coming in down here we that comes off energized as an n DH and we lose a carbon dioxide molecule and we get alpha glucaric acid down here a five carbon molecule so when that CO2 leaves we get a five carbon molecule now this five carbon molecule right we have pull in another NAD plus we get another nadh coming out so some of the energy has been transferred into this nadh and we get a second CO2 molecule coming off this means that we are now down to uh acetal I&#39;m sorry sual COA and at this point right we&#39;re now back down to a four carbon molecule um we can now bring in an adenosine diphosphate and essentially make an ATP out of that um getting lost a little bit in the weeds we actually go through a g DP and GTP intermediate in this but for our purposes we just have to realize that for every turn of the citric acid cycle we get an ATP molecule out and from that we just get cinic acid suic acid will go through this next reaction where an fad comes in goes out as an fadh2 we&#39;ve transferred some of the energy from cinic acid and turned it into fumic acid which will then go up here into the malic acid we got another NAD plus coming in forming an nadh again and reforming that oxil atic acid and then we can turn this whole cycle again with that next pyruvate because remember for every glucose molecule which starts glycolysis we get two pyruvate so every glucose molecule turns this cycle twice once for every P pyruvate and for every time this uh cycle occurs we get get an ATP molecule produced so the citric acid cycle produces one glucose for every turn and since we get two turns for every glucose molecule which enters the glycolysis process we get two atps per glucose which goes through glycolysis and then um down through the citric acid cycle so for the citric acid cycle we got a ATP molecule is formed for every time that Circle runs around we got a lot of nadh&#39;s and one fadh formed we actually got um three nadh&#39;s uh from the NAD pluses and we got one fadh from the or one fadh2 molecule from The Fad those F nadh&#39;s and fadh2 molecules are are used to drive the electron transport chain which we&#39;ll talk about in a minute so we also get co2&#39;s being produced in this because we start with a six carbon citric acid molecule at the start of the cycle which then gets dropped down to the four carbon oxil acetic acid uh at the end of all this and so two of those carbons get pulled off as CO2 and we actually lose them as carbon dioxides and so um a lot so most of the glucose molecules which come in basically get uh trans those carbons get transmitted out of the body as uh some of them at least as carbon dioxide molecules and so um we quite literally breathe out part of the food that we actually eat which is kind of an interesting concept so um this should be the last slide for this uh video on the next video we&#39;ll go into um a little bit more detail on this uh what actually happens next with the nadhs and the fadh2s look at um the uh electron transport chain and then figure out how we can feed in uh byproducts of fat metabolism and uh amino acid metabolism into some of the things which we&#39;ve already talked about and some of the things we&#39;ll talk about in the next video

this is the chapter on metabolism and just remember metabolism is what happens after the nutrients are absorbed what happens to those so we&amp;#39;re going to have to worry about is this uh component stored can what does this component used for is it used for ATP production if it is used for ATP production how do we get it into that Machinery used to make ATP so that&amp;#39;s a large portion of what we&amp;#39;ll be worrying about in this chapter is basically how ATP gets produced so let&amp;#39;s talk about carbohydrates at first so most of the carbohydrates we get come from plants we do get lactose from dairy products and so the monosaccharides which we&amp;#39;ll have to deal with uh are going to be glucose fructose and galactose those are the ones which uh we absorb from the diet there are a number of disaccharides out there sucrose which is normal table sugar maltose which is two glucose molecules stuck together and uh lactose or uh the milk or the sugar found in milk excuse me polysaccharides are the bigger complex uh carbohydrates as include starches uh from plant sources glycogen from uh animal sources both starch and glycogen are polymers of glucose they are slightly different in how the glucose molecules are put together and uh you know give have uh starching glycogen have different uh chemical properties due to the way that those glucose molecules are put together uh cellulose is another form of glucose cellulose is made by plants as a structural component and we are incapable of digestion of cellulose I.E it&amp;#39;s this wood product this is basically dietary fiber in a lot of cases and so the disaccharides and polysaccharides that we ingest are basically converted to glucose uh through the digestive process in the metabolism of the liver and then we&amp;#39;re either going to use that um glucose for energy util and turn it in well you use the glucose to turn it into ATP or we&amp;#39;re going to store it either as glycogen or we can convert that glucose into fat molecules into fatty acids and then store that as a triglyceride so what do we need carbohydrates for well we use them as um well a sources to get ATP uh any excess glucose which is coming in uh during uh a phase when you&amp;#39;ve just eaten that will be converted into glycogen glycogen can be stored in the liver uh skeletal muscle cells also store glycogen any excess once uh all the glycogen stores are filled up we can uh send that glucose into our Ayes and our Ayes can turn that into triglycerides and Stor as fat uh we also have to uh use uh carbohydrates to make DNA RNA ATP has a uh carbohydrate component to it and uh many lipids and proteins have extensive uh carbohydrates attached to them and so we&amp;#39;ll have to use um these incoming carbohydrates to make some of the specialized uh carbohydrates that we put out on glycoproteins and on the glycol lipids so lipids right about um 95% of all the triglycerides coming in get used for uh utilization as ATP uh we turn components of those lipids into ATP or they get stored directly in the adapost tissue and the liver now there are a large number of triglycerides coming in there the saturated uh fatty acids right uh and so um these guys have no double Bonds in their fatty acids and these guys are found in basically um uh in uh you know animal sources whole milk uh cheese and eggs these are all animal sources of uh triglycerides unsaturated fats and oils there are double bonds between these guys so monosaturated have one double bond this is um found in olive oil and uh peanut oil polyunsaturated fats have more than one double bond these are found in fish and in sunflower oil uh the and uh typically the saturated fats are worse for us than the unsaturated fats and trans fats are um processed polyunsaturated fats but the problem here is it&amp;#39;s the arrangement of that double bond um and across that double bond and uh Transat FS tend to while they are unsaturated do tend to be bad for us because they increase uh HDL levels and so if you avoid the trans fats you&amp;#39;re probably much better off and just stick with the naturally occurring uh unsaturated fats so cholesterol is found in the diet but again we make most of it uh we use cholesterol in our membranes we also use it for uh lots of hormones um right all the um hormones like testosterone estrogen progesterone aldosterone and a number of mineral corticoids Are all cholesterol-based uh components but cholesterol is not found in plants uh fossil lipids uh for example like gphin these are components of plasma membranes and we can get uh some of this material from egg yolks so uses of lipids that we need physiologically so we can turn components of lipids and generate a lot of ATP from them we will store triglycerides as an energy source in the adapost tissue and also in the liver the cholesterol which we are eating or basically U make we need those for bios salts we need those for uh all of our cellular membranes and all of the steroid based hormones uh estrogen progesterone testosterone aldosterone these are all uh cholesterol based steroid hormones we have the acoid these are derivatives of fatty acids these are uh signaling components of the inflammatory process they&amp;#39;re also involved in blood clotting tissue repair and the contraction of some smooth muscles uh phospholipids such as lethin these are important components of the cell membranes uh and we use them to make the myin sheaths they also form part of the bile so we use um you know lipids in a lot of different ways so proteins are basically long chains of amino acids and so we can break the amino acids down into those which are considered essential so uh essential amino acid is one which is not made by the humans we can&amp;#39;t make them so we are dependent upon them to come in from the diet so histadine isoline Lucine lysine methionine poly uhen alanine threonine tryptophane and valine they all have to come in from the diet uh conditionally essential right there are some conditions under which we are not able to make a certain number of amino acids right this is um you know if there are premature birth or certain metabolic problems right we can&amp;#39;t make Arginine cysteine glutamine glycine Proline and or tyrosine now there are some some amino acids we could consider they&amp;#39;re non-essential in the diet basically because if we get the essentials uh coming in we can make uh things like alanine aspartic acid aspargine uh Seine and glutamic acid but you know we&amp;#39;ve just listed basically all the 20 amino acids which are normally found as components of most of our uh proteins in the body so protein sources for the if it&amp;#39;s considered a complete protein Source basically all the essentials are in there so meat fish poultry eggs cheese um things like that uh are considered complete proteins incomplete proteins uh are missing some of the essential um amino acids but combination of incomplete proteins can give you a meal with all the essential amino acids in it and so you know um vegetarian and vegans do have to pay a little bit more attention to what they&amp;#39;re eating to make sure that they get proper nutrition but you can be totally healthy and have a vegetarian or vegan diet uh conversely to that if you are a vegetarian or vegan that doesn&amp;#39;t mean your diet necessarily has to be healthy right um you could be a vegetarian and still eat dairy products and eat nothing but milkshakes and chocolate chip cookies that would not be a very healthy diet but it would still be vegetarian so uh functions of proteins right proteins do a lot for us right so antibodies are proteins that have a protective function uh enzymes and hormones many of these components uh are uh protein in nature uh proteins form all have lots of structural components and uses in the body collagen all the basement membrane proteins uh muscle contraction and cytoskeletal elements are proteins and transportation right hemoglobin ion channels various uh membrane proteins which allow uh facilitate diffusion those are all proteins and Incredibly incredibly important so we also have to talk about vitamins right we often associate vitamins with good health but these are organic molecules which have to come in from the diet because we cannot uh make these things on our own so there are essential uh vitamins which must be obtained from the diet much like the essential amino acids and there are compounds which we have to take in which are considered provitamins which we are capable of converting into uh vitamins and so these include things like uh beta carotene uh seven dehydr cholesterol and tryptophane now vitamins are components which are required uh as co-enzymes these are uh co-actors which help the enzymes do their job and in a lot of cases the enzymes are inactive unless these co-actors are around and so um you know we need them they&amp;#39;re readily available from the environment in most cases and so they&amp;#39;re so readily a available that we don&amp;#39;t need to make them we get them from well the things that we actually consume so look at some of the vitamins right so we&amp;#39;ve got the fat soluble vitamins including vitamins a d b e and K now the fat soluble vitamins we can store in fat uh storage areas uh of the body and if we take in too many of these vitamins we can actually get to a level where some of these vitamins can become toxic uh high levels of vitamin A can actually cause bone and muscle pain uh skin disorders hair loss and cause the liver to get larger too much vitamin D can cause um too much calcium to be coming into the bodies and that calcium is going to start dropping out of solution in kidneys heart blood uh and in blood vessels so you know too much of anything is not good for you and too many of these vitamins can be bad for you uh water Sol water soluble vitamins excuse me include the B uh range of vitamins and vitamin C um these guys are water soluble and if these are present in the diet in excess they are normally excreted from the body uh uh quite quickly um mostly through loss of through the urine uh high levels of vitamin C can actually cause an inflammation condition in the stomach and can lead to diarrhea and so you know again too much of something is not necessarily good for you we need a number of minerals coming in uh from the diet right these are inorganic compounds like sodium and calcium magnesium things like that we need these to maintain uh normal homeostasis right if it&amp;#39;s a major mineral by definition we need 100 milligrams or more on a daily basis trace minerals less than 100 mix and so you know we need uh sodium pottassium chloride uh phosphate things like that um to you know for resting membrane potentials we need the resting membrane potentials for Action po Potentials in our nerves and in our muscles um we need calcium for our bones and our teeth um buffering system throughout the body phosphate um bicarbonate things like that uh you know we we need a lot of minerals and so we can get these from Plants Andor mineral uh and plant or animal sources excuse me uh but uh the minerals which are coming in on plant fibers are sometimes a little bit hard to absorb uh you know calcium can be hard to absorb trace minerals also includes things like copper and zinc ion uh or iron excuse me we we need all of these compounds uh in you know the right goldilock zone for proper health so let&amp;#39;s just start looking at metabolism and just getting a groundwork in some of the terminology that&amp;#39;s used and so when we talk about metabolism in a physiology setting right we&amp;#39;re talking about all and every chemical reaction which can occur in the body and so we&amp;#39;re not just talking you know about you know someone has an easy time of losing weight because they have a fast metabolism or I keep putting weight on because I have a slow metabolism no metabolism in this course will be referring to Every chemical reaction that can happen in the body and we can divide these reactions up into either catabolic or anabolic reactions so in a catabolic reaction we are releasing energy and we are breaking a larger molecules uh down into smaller uh molecules uh for anabolism we are requiring energy and we&amp;#39;re Pi taking smaller molecules and forming larger ones and so um you know an anabolic steroid is a steroid hormone which causes muscle to be formed so we&amp;#39;re making muscle so uh this is the way I remember that anabolism is making a compound catabolism is breaking it down and um so we get energy from nutrients most of that energy is converted into ATP and then ATP is the currency in which uh energetic reactions are basically powered throughout the body and drives all of these anabolic reactions so as an example of catabolic and anabolic reactions we&amp;#39;re looking at the formation and the utilization of ATP so ATP is this molecule shown here it&amp;#39;s got a ribo sugar it&amp;#39;s got a nucleotid like portion to it an adenosine and it&amp;#39;s got three phosphate groups attached to it now in an anabolic type of situation we&amp;#39;re using the energy from ATP contained in ATP and basically it&amp;#39;s most of that energy that&amp;#39;s utilizable physiologically is in the bond between the second and the third phosphate group those little uh yellow um circles with the p in it that&amp;#39;s a phosphate group and so when that energy is utilized that phosphate that terminal phosphate group is detached and quite often then reattached to the molecule which now needs that energy so that&amp;#39;s considered an anabolic reaction because we&amp;#39;re using that energy to drive the formation of some larger molecule now for catabolism we will actually you release energy from some compound that we&amp;#39;ve taken in from the diet and we&amp;#39;ll actually remake this ATP molecule so what we have to do there is we have to take this ADP this diphosphate molecule and reattach this phosphate group to it to increase the energy of ADP to the level of energy that&amp;#39;s in an ATP so that that ATP molecule can be reused again and so um you know we&amp;#39;re constantly generating ATP we&amp;#39;re constantly using that ATP and and uh need a steady supply of nutrients to drive the production of ATP and we&amp;#39;ll start getting into how the body actually generates ATP from carbohydrates proteins and fat sources later on in this video so if we look at overall how we generate ATP so on the left hand side here we can see we&amp;#39;ve got lipids here in this yellow we&amp;#39;ve got carbohydrates shown in blue and protein shown in uh the red um section of that graphic so what we&amp;#39;re going to do first is look at basically in great detail how we take carbohydrates run it through this glycolysis process run it through this citric acid cycle and then through um this uh bottom which is going to be the electron transport chain and chemo osmosis now what we can see is is that basically this process works uh quite well for glucose coming into this process because we have to remember that any monosaccharide coming in which isn&amp;#39;t glucose uh from the small intestines will be converted by the liver into glucose and either utilized or stored so we&amp;#39;re really talking about glucose metabolism here here now for lipids we can see that we can convert triglycerides and other lipids into components which we can feed into this Central carbohydrate mechanism likewise we can take proteins break them down into component into individual amino acids and then those amino acids can be fed into this basic pathway for carbohydrates and so what the next step is going to be is we&amp;#39;re going to be be looking at the how we break down uh glucose and turn glucose into ATP and at that point once we understand that process we can see how the breakdown components from lipids and the breakdown components of amino acids can also be fed into this uh metabolic machine for making ATP so carbohydrate metabolism so monosaccharides get broken down from the complex carbohydrates our livers will convert any non-glucose monosaccharides into glucose and that glucose will be utilized to generate ATP will be stored as glycogen or uh once the glycogen stores are fulled we can convert that glucose into lipids and then store that energy in that glucose in the form of lipids actually so the first step in breaking down glucose is a process known as glycolysis and so if we break this word down gluco here is referring to glucose Lis means breaking so we&amp;#39;re breaking down glucose and at the end of the process of um glycolysis we will form two molecules of what is known as pyruvate or pyruvic acid and so there&amp;#39;s a couple major steps in all of this U right but at the end of glycolysis we get four atps we get two molecules of this nadh stuff and two pyruvate molecules and all of these things are going to be important as we&amp;#39;ll see now if we go and look at these major steps so glucose comes into a cell we have to transport that glucose into a cell and one of the first things that happens is we use an ATP molecule to transfer that phosphate group from the ATP to the glucose molecule which is a little bit odd when you think about it because glycolysis is the first step in making ATP right this is how we turn glucose into into ATP and the first step uses an ATP molecule we&amp;#39;re actually in an ATP deficit right now because we&amp;#39;ve not turned that glucose molecule into any ATP yet all we&amp;#39;ve done is use an ATP to attach that phosphate to the glucose but overall we should just know that this is a phosphorilation process um what happens next is well we actually use another ATP at this point we have a molecule known as fructose 16 bisphosphate bis phosphate is referring to the fact that there&amp;#39;s now two glucos two uh phosphates on it excuse me and they are in the one position and the sixth position of the fructose molecule now this is still the fructose molecule is a six carbon molecule glucose is a six carbon molecule that&amp;#39;s important to know what&amp;#39;s important to know about pyruvate is pyruvate is a three carbon molecule so what happens here is we take the fructose 16 by phosphate and we turned it into well two molecules which each have three carbons a piece so we take a six carbon molecule turn it into a three carbon molecule and another three carbon molecule in this process we make nadh which is going to be a molecule which we run into later which carries electrons around the system and that&amp;#39;s important uh as we&amp;#39;ll see and we got ATP out of this process overall we get a net generation of ATP and we get pyate generated so important things to know some of the energy in that glucose molecule gets turned into ATP some of the energy from that glucose mole Ule is transferred into this nadh thing and the rest of that energy from that py is from that ATP is in the pyate molecule and some of that energy is just lost as heat that&amp;#39;s heat loss is just due to thermodynamics we can&amp;#39;t get around that that&amp;#39;s just the way the in the um Universe works now notice glycolysis makes four ATP molecules but it uses two ATP molecules so of those four ATP molecules which get generated the first two just basically are there to replace the two that we used to generate those four so at the end of the day each glucose molecule which enters glycolysis with will make a net of 2 ATP overall it makes four but we had to use two of those to basically energize the glucose molecule to prime the pump so to speak to get that energy out from that glucose molecule so we only get a net gain of two in spite of the fact that we&amp;#39;ve made four of these things right so the way to think about this is you know if you were to hand hand me um $2 and I handed you $4 right you would go oh this is a good thing right it you know I&amp;#39;m $2 down right but at the end of The Exchange I actually have $4 in my pocket when I only started out with $2 in my pocket right so you know you reach in your pocket there&amp;#39;s only $2 in there you hand them to me and I hand you $4 and you put them in your pocket and you now go ooh I have $2 more dollars at the start at the end of this process than when I started out and then you go can I do this again please right and so we are generating ATP from glycolysis it costs us 2 atps but that&amp;#39;s okay because we get a net gain of 2 atps at the end of the day because we&amp;#39; made four total atps in glycolysis so let&amp;#39;s look at this in some excruciating detail so at the top here we can see a glucose molecule now that glucose molecule is brought into the cell transported across the membrane and one of the first things that happens is we burn an ATP and we attach that phosphate group to the sixth position the six carbon and so now we have a molecule of glucose 6 phosphate that rearranges itself into a fructose 6 phosphate molecule and we burn another ATP this ATP is now attached to the one position so we get a molecule of if I can find my pointer fructose 16 bis phosphate we right we&amp;#39;ve got a phosphate here and a phosphate group here on this five carbon sugar this fructose molecule actually it&amp;#39;s a six carbon uh molecule the Rings only five excuse me now this is where we&amp;#39;ve used those first two atps now this is a six-carbon molecule it gets broken up into those two three-carbon molecules um one of them is a glycer aldhy 3 uh phosphate this molecule here on the right the other one is a dihydroxy acetone uh phosphate molecule over here but this molecule on the left gets converted into the glycer aldhy 3 phosphate so basically the way to think about this is we&amp;#39;re just making two copies of this molecule and then this molecule so we&amp;#39;ve taken a glucose molecule a six carbon molecule brought it into the cell phosphorated it I.E transferred that phosphate group uh that converts itself into that fructose 6 phosphate we attach another phosphate group to it again burning another ATP to get the fructose 16 bisphosphate and that breaks up into those two three carbon molecules right and so that&amp;#39;s glucose up well as far as we&amp;#39;ve gotten on this slide so let&amp;#39;s go to the next slide so we&amp;#39;ve got that well basically two copies of the glycer alide 3 phosphate and we bring in two molecules one for each of the glycer alide three phosphates of an nad+ and we turn that into an nadh this is going to be important because that nadh is a carrier of that electron and some of the energy from that glucose molecule is in that uh nadh molecule so at this point we can bring in an a DP molecule one each for every of the glycer alide 3es and remember we&amp;#39;ve got two of those glycer alide 3s and we get our first two ATP molecules made we then go through a couple other steps and we bring in two more adps and we get two more atps and a pyruvate molecule at the end of the of all this so bring the glucose molecule in burn an ATP burn another ATP we now split that six carbon molecule into two three carbon molecules each one of those three carbon molecules has a phosphate group on it and we can transfer that phosphate around and basically convert 2 a two adps into into two atps and then we can convert another 2 ad DPS into two atps at the end of glycolysis and end up with the pyruvate molecule so when glucose enters we get a net gain of two atps we get two pyate molecules and we get two molecules of the nadh at the end of glycolysis that&amp;#39;s what we that&amp;#39;s really what I want you to know about glycolysis for all of these metabolic reactions I don&amp;#39;t expect you guys to memorize the structures of all these compounds I don&amp;#39;t want you to memorize each and every step but I want you to know the overall process glycolysis starts with glucose we use two atps we get four atps out of glycolysis overall but since we burn two atps the net gain from glycolysis for atps is only two but we do get two pyruvates and two nadh molecules and we get those nadhs from the nadh plus molecule which is going to be important in a minute and remember that some of the energy from that glucose is in that nadh and some of it is also in the um pyruvate and certainly some of it is in the 28 the net a two atps that we produced so if we look at the overall ATP production from one glucose molecule right we got well two atps overall we got well some energy is in those two nadhs and in those pyrates so those are the those other products and there still energy in there then everything else on this chart we haven&amp;#39;t talked about in any detail at all except just letting you know that these things exist right so when we make this compound acetyl COA shown here right we get two more adps here um when we get into the citric acid cycle here we generate two atps and we get six more nadh&amp;#39;s and two molecules of an fad H2 which has a very similar um role as the nadh molecules now in the electron transport chain we make 28 atps in a very mysterious way which we&amp;#39;ll get into in the next video and we also make some water molecules now at the end of the day in theory from a single glucose molecule we can make 32 atps two from glycolysis two from from the citric acid cycle that gets us four and then another 28 from the electron transport chain and so we drive the electron transport chain using well the energy in the nadh&amp;#39;s and the fadh2s we&amp;#39;ll see that in the next video but and that 32 atps from a single glucose that&amp;#39;s the theoretical maximum sometimes there&amp;#39;s a little bit of inefficiency Sometimes some of the membranes are a little bit leakier than what they need to be as we&amp;#39;ll see for the electron transport chain and so sometimes we will&amp;#39;ll only get 28 sometimes we&amp;#39;ll get 30 but anywhere from 28 to 32 ATP molecules are generated on average from a single glucose molecule which starts this process all right so we now have to deal with the roles of oxygen in uh metabolism so that brings up aerobic and anerobic respiration up first is Anor robic this means we can break down glucose to get ATP with no oxygen in absence of oxygen molecules we can do this now if there&amp;#39;s no Oxygen present during glycolysis we have to take the pyruvates that are made and generate lact lactate or lactic acid molecules from that um we do that because we need to regenerate those nadh molecules those NAD plus molecules I should say those nadh plus molecules get turned into the nadh molecules if we don&amp;#39;t have nad+ molecules the glycolysis process stops and so in order to get nadh I&amp;#39;m sorry to get nad+ molecules back we have to turn the nadh molecules back into NAD pluses and to do that by doing that we can basically take that nadh take that hydrogen off that H part put it onto the pyruvate molecule to make the lactate molecule by doing that we regenerate the NAD plus so that glycolysis can keep on moving in spite of the fact that there&amp;#39;s no Oxygen around basically this has to happen because oxygen is required for pyruvate&amp;#39;s next couple of steps now if if oxygen becomes available at some later point we can convert that lactate back into U pyruvate or back into glucose by the Corey cycle uh and um we can get some of that energy back because some of that energy from the glucose molecule is still now in that lactate so anerobic respiration as we&amp;#39;ll see we can break down uh glucose with no o oxygen around we get U two molecules of lactate and two molecules of ATP so this is with no oxygen around right so this is um you know what happens in our cells when uh particular our muscle cells when they become short on oxygen just due to the fact that we&amp;#39;re you know really uh Contracting that muscle using a lot of ATP and our cardiovascular system is just not in uh capable of getting enough at ATP or enough oxygen in there to generate enough ATP and we can do this for a short amount of time in some of our uh anob muscles and so if we look at this in uh this Anor robic uh respiration so we have glucose here it goes through glycolysis uh shown here as number one we get our two pyate molecules but um we have to uh regenerate those NAD pluses so remember we get those two nadhs from as byproducts from turning the glucose into pyate but we now have to take those nadhs use them to convert the two pyrates into the two lactate molecules that regenerates the in a d plus molecules which will allow the next glucose molecule to be turned into two Pates and uh eventually into the two lactates right but we are still in that process generating two atps so we can still generate ATP in the absence of oxygen using this process as you&amp;#39;ll find out when you go through your um microbio biology classes a lot of microbes uh can generate atps live quite nicely with no oxygen whatsoever U this is how botulism toxin can survive in improperly canned goods for a very long time and cause problems for humans when they eat that food because botulism toxin is really really nasty and um the botulism bacteria can grow quite nicely in that nice sealed jar because it doesn&amp;#39;t need any oxygen and has lots of things to chew on uh because well you&amp;#39;ve preserving food sources uh in that jar and um yeah Anor robic uh bacteria uh can are nasty little buggers from a health standpoint so in contrast to that is what happens when there&amp;#39;s oxygen around in aerobic respiration so um we can break down the glucose with oxygen around to make carbon dioxide water and eventually 32 molecules of ATP but that isn&amp;#39;t going to include what we get from glycolysis and then the subsequent breakdown of that pyate through the um citric acid cycle and the um electron transport chain now most of the ATP which we generate comes from having oxygen around and so we have to go through glycolysis we then have to form this acetal COA compound we then run molecules breakdown products of that pyro pyate excuse me through the citric acid cycle we will get some atps directly from the citric acid cycle but in the electron transport chain we will use the nadhs and the fadh2 molecules generated from glycolysis acetal COA formation and the citric acid cycle we will use the energy in those molecules to make 28 out of those 32 atps in the electron transport chain so we&amp;#39;ve got aerobic respiration in uh well generalized here so we&amp;#39;ve got glycolysis right we take glucose we make two py two pyate molecules we get a Net G gain of two atps and we get two nadhs we then take those pyrates and we turn them into acetal coaz that generates uh nadhs and we still have some of that energy in that acetyl COA that acetyl COA molecule is fed into this citric acid cycle which we&amp;#39;ll go into detail in a little bit from that we get well some CO2 molecules we got some six nadh&amp;#39;s we get two molecules of fadh2 and we actually generate two molecules of ATP for every glucose molecule which starts through this process I.E the glycolysis process the electron transport chain will use all of the nadhs and the fadh2s that are generating to make well those 28 out of the 32 atps now this is where oxygen is really required and that oxygen will combine with some protons to basically form water molecules and uh we do create water as a byproduct of aerobic respiration so let&amp;#39;s look at some detail on how the pyate which we get from glycolysis gets converted into acetal COA in this process we do release a carbon dioxide molecule now this happens in the mitochondria those little tiny organel which everyone remembers as the PowerHouse of the cells now there is an nadh molecule made during this process so let&amp;#39;s take a look at that then we have to run everything through the kreb cycle uh we get basically a production of citric acid because at that point we have an oxil acidic acid which is part of that cycle and this incoming acetal COA they get together and make a citric acid molecule hence the Centric acid cycle name we then run through a series of reactions with the Centric acid molecule at the end of the day for every turn of this citric acid cycle we get an ATP molecules made we get nadh molecules we get fadh2s we get carbon dioxide and we get that oxal AIC acid back and since we have an oxal AIC acid back we can cycle around again uh for uh well when we generate another acetyl COA uh from well the pyate molecule so the pyate molecule is shown here it&amp;#39;s a nice three carbon molecule it&amp;#39;s in the cytool it moves from the cytoplasm the cytool basically into the mitochondria and the mitochondria has an inner membrane space uh within its own uh membrane and the Matrix uh is has an inter mitochondrial membrane in it so we take that pyate we basically which remember is a three carbon molecule we remove a carbon and that carbon leaves as a CO2 molecule now in that process we take one of these nadh I&amp;#39;m sorry NAD pluses and turn it into an nadh so some of the energy from that pyate has been transferred to that nad+ and becomes an nadh basically because we moved an electron onto it and then we get what&amp;#39;s known as an acetal group an acetal group is a two carbon group and this acetal group is a um important molecule in the metabol in a lot of metabolic pathways as we&amp;#39;ll see and so uh just remember that the acetal group is a two carbon molecule and has uh it&amp;#39;s a major crossroads uh in metabolism in that we can use this acetal group to feed into the citric acid cycle we could use this acetal group to make fats if we needed to or to make carbohydrates if we needed to this acetal group if it&amp;#39;s moving forward into the citric acid cycle gets hooked up with what&amp;#39;s known as co-enzyme a and then with once that uh twocc carbon group attaches to the co-enzyme a we get an acetal Co an acetal COA and so this Cycles around all the time Co COA will uh get together with this acetal group to form the acetal COA and then that acetal COA will get fed into the citric acid cycle so here you can see the citric acid cycle in all of its Glory so we have the acetal COA coming in from the top here and it gets together with oxil atic acid which is this four carbon molecule right here and so that gets together and forms citric acid which is the namesake for this entire cyclical process now this becomes isocitric acid and then at this point we have an NAD plus coming in down here we that comes off energized as an n DH and we lose a carbon dioxide molecule and we get alpha glucaric acid down here a five carbon molecule so when that CO2 leaves we get a five carbon molecule now this five carbon molecule right we have pull in another NAD plus we get another nadh coming out so some of the energy has been transferred into this nadh and we get a second CO2 molecule coming off this means that we are now down to uh acetal I&amp;#39;m sorry sual COA and at this point right we&amp;#39;re now back down to a four carbon molecule um we can now bring in an adenosine diphosphate and essentially make an ATP out of that um getting lost a little bit in the weeds we actually go through a g DP and GTP intermediate in this but for our purposes we just have to realize that for every turn of the citric acid cycle we get an ATP molecule out and from that we just get cinic acid suic acid will go through this next reaction where an fad comes in goes out as an fadh2 we&amp;#39;ve transferred some of the energy from cinic acid and turned it into fumic acid which will then go up here into the malic acid we got another NAD plus coming in forming an nadh again and reforming that oxil atic acid and then we can turn this whole cycle again with that next pyruvate because remember for every glucose molecule which starts glycolysis we get two pyruvate so every glucose molecule turns this cycle twice once for every P pyruvate and for every time this uh cycle occurs we get get an ATP molecule produced so the citric acid cycle produces one glucose for every turn and since we get two turns for every glucose molecule which enters the glycolysis process we get two atps per glucose which goes through glycolysis and then um down through the citric acid cycle so for the citric acid cycle we got a ATP molecule is formed for every time that Circle runs around we got a lot of nadh&amp;#39;s and one fadh formed we actually got um three nadh&amp;#39;s uh from the NAD pluses and we got one fadh from the or one fadh2 molecule from The Fad those F nadh&amp;#39;s and fadh2 molecules are are used to drive the electron transport chain which we&amp;#39;ll talk about in a minute so we also get co2&amp;#39;s being produced in this because we start with a six carbon citric acid molecule at the start of the cycle which then gets dropped down to the four carbon oxil acetic acid uh at the end of all this and so two of those carbons get pulled off as CO2 and we actually lose them as carbon dioxides and so um a lot so most of the glucose molecules which come in basically get uh trans those carbons get transmitted out of the body as uh some of them at least as carbon dioxide molecules and so um we quite literally breathe out part of the food that we actually eat which is kind of an interesting concept so um this should be the last slide for this uh video on the next video we&amp;#39;ll go into um a little bit more detail on this uh what actually happens next with the nadhs and the fadh2s look at um the uh electron transport chain and then figure out how we can feed in uh byproducts of fat metabolism and uh amino acid metabolism into some of the things which we&amp;#39;ve already talked about and some of the things we&amp;#39;ll talk about in the next video

Transcript for:Metabolism Overview

Transcript for:
Metabolism Overview