hello welcome to part seven you have come to the end we need to look at the second half of cell respiration and which is going to be the citric acid cycle or the krebs cycle and we need to look at this idea of the electron transport chain and what does this mean for atp please keep in mind that just as a refresher where we left off at the end of glycolysis we have in the bank two net atps we created four but we had to pay the bank back two from the investment phase and so we have two to the good for atps and we also created these two molecules of pyruvate or pyruvic acid for which we used to create a molecule of or two molecules of acetyl coenzyme a um it should be noted that each of those pyruvic acids that we created at the end of glycolysis each one will fuel or power the krebs cycle one time so we can actually crank the krebs cycle twice for each molecule of glucose that enters into the process of cell respiration starting with with glycolysis because again at the end of glycolysis we have two pyruvates or two pyruvic acids each one of those will create a molecule of acetyl coenzyme a which in turn will turn the krebs cycle one full crank so we get two cranks of the krebs cycle for each molecule of glucose that enters into glycolysis and we're not going to spend as much time with the krebs cycle because it is it is scary all right um but i'm going to give you the important things that you need to know which are mainly what are the byproducts what are we getting out of this cycle of the krebs cycle and what is the purpose and i will tell you that the purpose is you end the krebs cycle with exactly what you start with so in other words we we start the krebs cycle with this thing called citric acid you end the krebs cycle right with the precursor to citric acid um and what so what does all this mean well acetyl coenzyme a is going to join with a molecule that is known as oxaloacetic acid so oxaloacetic acid joins with acetyl coenzyme a to form citric acid and the rest of the krebs cycle is about taking that citric acid breaking it down and recreating acid so that it can join with another acetyl coenzyme a to form another molecule of citric acid to crank the krebs cycle once again all right um so what's what does this look like all right what does this look like well here's the krebs cycle okay again i told you it was ugly there's a lot of enzymes in here and there's a lot of um um redox reactions or reduction and oxidative reactions that are taking place here but here's here's what i want to draw you draw your attention to all right here is pyruvic acid being converted into acetyl coenzyme a and look at what we produce we produce a nadh right we produce an nadh we produce one of those nicotine nicotinamide adenine dinucleotides and we create a molecule of co2 and that is what we're creating when we uh ultimately produce this acetyl coenzyme a acetyl coenzyme a merges with oxaloacetic acid to form citric acid then watch we come through don't worry about what all of these little intermediaries are all right but we're coming down and look we create another molecule of nadh we create another molecule of co2 so now that's two nadhs two nadhs two co2s we're going to come along a little bit more oh we're creating another nadh and we're creating another co2 keep going hey we're creating an atp going hey we're creating this thing called fadh2 flavin adenine dinucleotide flavin adenine dinucleotide so we're creating one of these guys and we're continuing along and oh we're creating another nadh and by the time we create this nadh what do we have again oxaloacetic acid you start and end with the same thing so that this oxaloacetic acid can now merge with another acetyl coenzyme a to produce another molecule of citric acid to be able to run this again remember what i said this happens twice each glucose molecule is producing two pyruvic acids which is enough to produce two acetyl coenzyme a's which will turn this cycle twice why is that important well that's important because look at our end products for each glucose for each pyruvic acid that creates acetyl coenzyme a that merges with oxaloacetic acid to create citric acid we are creating three carbon dioxides that's going to be important that's what we exhale all right we're going to create four nadhs this is here's here's why nadh and fadh are important they carry hydrogen protons they carry hydrogen protons and that is in that is critically important for the electron transport chain and we'll we'll talk about that there in a few more minutes right so for each crank of the krebs cycle we are creating four nadh molecules we are creating one fadh two molecule one flavin adenine dye dinucleotide and we're creating a lonely molecule of atp but remember we're cranking this how many times twice so in actuality we are producing for each glucose molecule that enters into glycolysis we are producing six molecules of co2 we are producing eight molecules of nadh we are creating two molecules of fadh and we are creating two molecules of atp we can add these two molecules to the two from glycolysis and now we have four net atps produced so far right yes we're technically six but remember we had to pay back two so we're at a net of four and all of these guys are now head i shouldn't say not all of these guys that the atps go to the atp bank nadh and fadh now go off to the electron transport chain and the electron transport chain is all about the oxidation the removal of a proton from nadh and fadh and the h is hydrogen it's a hydrogen proton remember it's only got one proton in it that's it it is a proton and so the electron transport chain is all about stripping away the hydrogen proton off of nadh and fadh2 so that those hydrogen protons can be used to do oxidative phosphorylation which is the process of creating atp through the use of a hydrogen proton gradient that was created from the oxidation or the stripping away of hydrogen from nadh and fadh2 let that sink in oxidative phosphorylation is the production of atp powered by a hydrogen proton gradient that was created from the oxidizing or the stripping away of hydrogen protons from nadh and fadh2 here is the stripping away of the hydrogen protons so you can see down here you have your nadhs your fadh2s you've got some proteins in here that are directing the oxidation the stripping away of that hydrogen proton and look accumulating on the outside of the cell membrane or i should say the inner membrane of the mitochondria accumulating on the outside of the inner membrane of the mitochondria are hydrogen protons and those hydrogen protons charge the outside of the inner membrane of the mitochondria so that it is really positive and what happens when you get all of these positives together where they try to repel one another so how do they do that well they've got to find their way to the other side of the membrane and the way to get to the other side of the membrane is through a enzyme called atp synthase atp synthase atp synthase is this guy right here all right and so what are the components of this atp synthase well atp synthase is made up of a couple parts it's got a rotor it's got a rod and it's got a knob and what ends up happening is the hydrogen protons that are in high concentration on the outside of the inner membrane of the mitochondria pass through this stator right this stator is this is this it's almost like a rest all right by which the rotor sits on and so the hydrogen protons come down here into the stator and that powers the rotor to turn and in turn it cranks the rod all right and as it does that it actually brings the hydrogen proton down into the inside of the inner membrane so you can see hydrogen proton comes passing through the stator right that hydrogen proton cranks itself around the rotor as the rod turns it forces the hydrogen proton out and the rod is then turning this knob and it's the job of the knob to add the phosphate group onto the adp creating a tp you've done phosphorylation you've added the phosphate group onto the atp by using a hydrogen proton concentration gradient how freaking efficient is that i'll tell you because we do this process of chemoosmosis this idea of using a hydrogen proton concentration gradient to fuel and power an enzyme such as atp synthase for the sole purpose of doing phosphorylation adding the eight the phosphate group onto the atp the electron transport chain produces 34 atps 34 atps why because we're not using atp to create atpc that's the downfall of glycolysis glycolysis is using atp to create atp remember the investment phase we invested two atps we don't see that with the chemiosmosis or with the electron transport chain instead we see using a hydrogen proton to create an electrical charge that will power the enzyme to create the atp through phosphorylation where in the world did our body come up with such a great idea bacteria this is an evolutionary remnant to when mitochondria which is where this is taking place was an independent living organism mitochondria 3.8 billion years ago was a bacterium that eventually formed a symbiotic relationship with other bacteria what so our mitochondria our mitochondria are bacterial and it reeve and it kept this basic principle of fueling structures using a hydrogen proton gradient bacteria today still use hydrogen proton gradients to fuel its little flagellum bacteria don't have enough atp to be able to produce to power their flagellum to keep them moving it's too expensive they're too tiny they would burn out the amount of heat that would be dissipated from having to create that much atp would literally singe that little bacteria and so they use hydrogen proton gradients and the earliest mitochondrial ancestors maintained that when mitochondria developed the symbiotic relationship with other bacterial cells bigger than them mitochondria doesn't have the same chromosomal structure that we do in fact they've got circular dna that is completely separate and independent from every other genetic material in the human body it doesn't do mitosis mitochondrial don't engage in cell division such as mitosis binary fission which is the same process that most bacteria use to split into two your mitochondrial are bacterial it's a remnant left over highly effective primitive bacteria living in each and every cell of your body and it takes that primitive mechanism of creating atp and it maximizes it during the process of cell respiration to give you the biggest bang for your buck and you take those 34 atps and you add it to those two atps that we created during the krebs cycle and you add it to the four atps that you did that you created during glycolysis and you create 40 atp molecules from each molecule of glucose but remember you got to pay the banker so we've got to take two of those atps away and what do we end up with you end up with between 36 and 38 atp molecules and muscle cells they're not as effective the mitochondria is typically not as effective but in muscle skeletal muscle cells there's an overwhelming number of mitochondria so it's it kind of evens out but mitochondria and muscle and skeletal muscle produce about 36 atps overall all right fascinating evolutionary connections that are living in us today in every cell that we rely on we would die we would not be able to exist as a complex multicellular organism if it wasn't for these primitive symbiotic relationships that we have formed and we still maintain today with bacteria this is a pretty picture that shows you where glycolysis happens i think glycolysis glycolysis is happening within the cytosol and then the krebs cycle and good old transport the electron transport chain is happening within the mitochondria this the picture right here um this just kind of tells you when we talk about cellular respiration we're talking about aerobic respiration typically all right um because you got to do something with that electron from the hydrogen and so it's usually the oxygen that's accepting the electron well we there's two other ways of doing uh types of cell respiration anaerobic cellular respiration and fermentation and anaerobic respiration the final electron acceptor is not oxygen it is some kind of inorganic molecule and because of that it yields fewer atp molecules so typically anaerobic respiration not done in the presence of oxygen will yield between 2 and 36 atps now i will say this anaerobic respiration still engages in glycolysis krebs cycle and electron transport chain and during glycolysis it still produces a total of four atps during kreb's cycle it still produces two atps where it varies is during the electron transport chain because it's not using oxygen as that final acceptor and so it's not as efficient as at releasing hydrogen protons and so it's not going to be as efficient um it's not going to be efficient in producing as many atps as it does during aerobic respiration all right and so it uses nitrate ions um it uses sulfate ions um it uses hydrogen sulfide that's h2s over there and it uses carbonate ions that's this guy right here all right so this is a nitrate ion this is a sulfate ion this is hydrogen sulfide over here and this is a carbonate ion right there then we've got this little thing called fermentation which i absolutely love fermentation is amazing fermentation does not use any kind of no oxygen is required and here's the thing fermentation does not do the krebs cycle fermentation is a process that is done by bacteria and yeast and depending on what is what is doing the fermenting it will ultimately depend on what your uh your byproduct is all right so both bacteria and yeast many types of bacteria and yeast will do fermentation so uh they still do glycolysis all right uh which is why they produce two atps right two net atps it's because of glycolysis the actual process of fermentation does not produce any atp all right um and so this is this is a highly ineffective way of doing things but your bacteria for the most part will do fermentation and will produce something called lactic acid right so this is what gives swiss cheese the holes right bacteria are producing gas that's being released as this lactic acid and that's created a is what curdles the milk and makes the cheese go but it makes the milk go bad which is what produces the cheese to begin with same thing with sour cream same things with cottage cheese all that stuff there that is really bad sour old milk is all produced because of lactic acid released from the bacteria but think about how many good things we get from that though i think about all the cheeses that we get think about the yogurts that we get and all that kind of good stuff um so our food supply depends on lactic acid and fermentation but when yeast engage in fermentation they still produce a net of two atps through glycolysis but it is in fermentation the yeast do not produce lactic acid the yeast produces ethanol yeast produces ethanol um uh servatia all right cervatia that's a type of yeast that produces that's a that's brewer's yeast um it's what we use to produce and make create milk or i'm sorry nut milk beer all right the end product of fermentation though done by yeast is ethanol it's grain alcohol and so all of your not your beer your wine um your bourbons your whiskeys your vodkas all of those things are all dependent upon yeast fermenting sugar what creates the difference is the boiling temp the type of yeast that is used and very often the type of grain that is used all right so whether it's barley whether it's wheat whether it's rye whether it is some kind of mash that you use like within beer like corn so the grain that you are using very often determines whether or not you're going to make a bourbon or a whiskey or whether you're going to make a vodka or or a bourbon or whether you're going to make beer or whether or not you're going to make wine and of course with wine your your your what's doing what's being fermented is the fruit it's the grapes typically grapes right that are being fermented um and so it's not a grain at all it's not a grain at all most of your beers are going to be wheat based all right and then your barleys and your ryes and your corn is what's going to be producing your your bourbons your whiskies your your vodkas so fascinating stuff for fermentation it is horrible at producing atp but we get so many good beneficial things from the process of fermentation so this is just a nice little summary table for you this goes back to way back video 2 3 on looking at diffusion and osmosis all right endocytosis and exocytosis is right here so this is kind of a nice little summary table of passive and active transport that i wanted to give you guys and so uh at that um you have come to the end i'm not going to do a review of mitosis i'll probably post some some some things for you for that but i'm not going to do a video on mitosis or i should say the cell cycle because we covered that pretty heavily in the lab um so i will post some review stuff for you for that so there's not going to be a video on um on mitosis specifically all right but i will give you some review material on that and so with that said congratulations the two hardest chapters are done in my opinion chapter two the biochem chapter three cell bio is now done these are the most heavy laded uh content chapters that we have through all of amp one so you have survived in my opinion the worst of the course everything from here on out is all about application and use of everything that we have learned in chapters one two and three and so congratulations and i'll catch you on the flip side