hey everybody row this we're going to talk about the electron transport chain or the electron transport system so we've already been through glycolysis we've already been through the intermediate step we've already been through the Krebs cycle we generated a little bit of energy right we've made a total of four ATP that gain of two during glycolysis and then two during the Krebs cycle but as humans we had to spend two of those to get to get all these building blocks into the mitochondria anyways so we've barely made any energy but this entire time we've been collecting what I call the casino chips we've been collecting these full electron carriers that are now loaded down with electrons and hydrogen ions and we're gonna cash them in that's gonna be where energy is produced so this is called the electron transport chain that's exactly what it does but as you're gonna see here at the end it's the movement of protons that actually generates the energy needed to make ATP before we move any further you see these H pluses all over the place we can call them hydrogen ions or protons now the reason we can call them either is hydrogen is the only element on the periodic table that doesn't have a neutron so that means hydrogen is a proton and an electron well a positive hydrogen ion has its electron removed and that's why all that's left is a proton so don't be confused by that if someone's talking about proton pumps or proton pours or whatever they mean the same thing as hydrogen ions and I think protons are probably a fine word there okay so we're also looking at the process of oxidative phosphorylation the energy made prior to prior to this like during the call says where we weren't using oxygen was called substrate level phosphorylation so this is going to be oxidative phosphorylation okay so let's get let's go through this I know this is complicated but we have all we've brought in all these NADH is remember NADH used to be nad plus it became an idea H as it was loaded with electrons and hydrogen ions fa d HB came this fadh2 so now they're gonna come and dock on the electron transport chain and they're going to give up their electrons on their hydrogen ions so nadh is going to be able to generate enough energy to lead to the production of 3 ATP fadh2 as you can see here you know kind of starts later and is able to generate enough energy to make 2 ATP so those are kind of key things there but the key thing to note is now you have all these hydrogen ions and all these electrons as electrons are transported step-by-step through the electron transport system each time an electron is removed or transferred it gives a little bit of energy and this energy accumulates and when you have enough energy from the movement or flow of electrons you can now pump hydrogen ions so as then so these are these are hydrogen ion pumps or proton pumps and that and as electrons transfer through them they get a little bit of energy at a time and that gives them enough to pump out hydrogen ions so we've been calling it the electron transport chain which it is but it is this movement of hydrogen ions outside of this inner mitochondrial membrane in us in bacterias would be happening in the cell membrane and then back through is actually energy is going to be generated so there you see the electron transport system you have those three big proton pumps then you have your mobile electron carriers just to make this clinically significant the poison cyanide will actually block that cytochromes see right there in the middle which is why people that were poisoned with cyanide like in the movies where spies poison themselves rather than talk or whatever they died relatively quick really quickly because if you shut off the electron transport system then you you can no longer this the flow of electrons stops which means that ATP production would stop as well the other thing to note here is as these electrons are used up they need a final electron acceptor and that's gonna be oxygen so they're at the bottom of the image oxygen is going to accept these electrons once they've helped the the proton pumps work oxygen is going to accept those electrons and become water so this is why we we need oxygen we use aerobic respiration oxygen is our final electron acceptor there are other living things that don't use oxygen as the final electron acceptor but we need it so without oxygen same problem this is the reason that we breathe in is because if we don't get oxygen then we can't we cannot generate ATP and this is also the reason we breathe out because as you've seen during the intermediate step and the krebs cycle we produced carbon dioxide that we had to get rid of so your metabolism is what requires oxygen and generates co2 but okay so now we have it we have let's let's look up all these hydrogen ions here at the top we've created a concentration gradient and for several reasons number one so there's more hydrogen ions outside of this mitochondrial membrane than inside of it so diffusion says that these are going to be slamming in each other they hate each other they want to move right the example I use in classes is of each of these hydrogen ions had jump rope and they were whipping each other they'd want to spread out so they want to diffuse back into the cell so just the fact that there's a concentration gradient is reason enough but they also had it's called an electrochemical gradient because they have the same a charge and likes repel each other so electrically and chemically they want to leave they do not want to be here and then you could also make an argument that because they're their hydrogen ions they're positive a little bit of a pH diffusion issue here too but for so for multiple reasons 2 or 3 depending on how you want to look at it these hydrogen ions want to get back inside the inner mitochondrial membrane and if they do they can but let me go ahead and show you a little better image you can see a little bit the inside here the cells the the mitochondria or the electron transitions fine if you want to come back in that's fine but you have to come in through this enzyme this enzyme here is called ATP synthase it's specifically called a protein pore complex but ATP synthase is fine as hydrogen ions or protons flow through it it causes spinning there's a turbine it's basically an enzyme it's a turbine so think about like a wind turbine how when wind turbines spin the generate energy hydroelectric energy is water causing turbines turbines to spend nuclear power plants generates steam to cause it's a steam driven turbine so when things spin they generate energy that's that's that's common in the world around you it happens inside your cells too so as these hydrogen ions flow through these protons flow through ATP synthase it causes it to spin and this turbine spinning generates the energy needed to take ADP and add that third phosphate to it to make ATP adenosine triphosphate so this process the flow of hydrogen ions or protons here is called chemiosmosis just in case you ever see that term so in the end we needed all these electrons to power the electron transport system so that we could pump a bunch of hydrogen ions out of the mitochondrial membrane or wherever this is occurring in bacteria and then as they as they flow back in they generate the energy needed to make ATP so this is why you have to eat every second right you're either eating or your body's eating stored reserves because if you don't constantly keep these electron transporters bringing electrons then the system shuts off and without electrons you'd no longer be pumping these hearts and ions and we wouldn't have this electrochemical gradient and they'd stop flowing and you would quit generating ATP so all right so that's the I know this has been a lot but this is the so we've now been through glycolysis the intermediate step the Krebs cycle and the electron transport system so hopefully you now see how we've gone from food glucose our fuel to 36 ATP's in human and 38 ATP in bacteria so you've done it I hope I hope you grasp it at least to some level I get it it takes a lot of time maybe watch the videos more than once come back in a few months and review this just this is a very difficult process to understand and I hope you grasp it a little bit better now alright I hope this did help have a wonderful day be blessed