[Music] hello everyone this is andy from med school eu and today we're going to continue on with the topic of bioenergetics and more specifically we are going to discuss redux reactions in living things so first of all what are redox reactions and where do we use them in living things so redux reactions are energy capturing and energy releasing processes that largely consist of oxidation and reduction reactions called redox reactions so let's talk about oxidation and reduction because a redox reaction consists of two parts oxidation and reduction and they're coupled so if something is oxidized something else must be reduced within the same reaction basically the whole cornerstone of this information that you really need to know is that the process of redux reactions and oxidation reduction reactions it refers to the transfer of electrons so you should know that that this is all about transfer of electrons and then the reaction transfer of electrons would be also coupled with the transfer of protons in order to balance out the energy so what we've got is oxidation and oxidation is the loss of electrons loss of electron and reduction is the gain of electron gain of electrons so if one molecule is oxidized another molecule must be reduced within the same reaction and that's that's the that's the only thing that you really need to know about redux reactions and when they occur especially when we go through the process of glycolysis and other energy metabolizing processes i'm going to point out some of the reactions that would be going through oxidation and some they'll be going through reduction so now we're going to take a look at the oxidation levels of uh carbon compounds so another thing to note is that the more oxygen atoms that we've got the more oxidation levels that we have the more they are oxidized so here we have a carbon attached to four hydrogens meaning that it is fully saturated with hydrogens it because it's got the for the maximum four bonds it can have now if we are going from a methane so this is a methane molecule if we're moving down a level to an alkane which has a bond to another carbon molecule now here this carbon is no longer fully saturated it's not a methane ch4 it's a ch3 it's an alkane here and because of that because the carbon does not contain the maximum amount of carbon hydrogen bonds it is then on a it is more likely that it is oxidized now if we're moving down another level we've attached an oxygen molecule so so this would be an aldehyde and that's going down this could be an aldehyde or we can make it a ketone where has a double bond to an oxygen now this would consider to be another level of oxidation so moving on next we have another oxygen bonded to it with another oxygen there so that's that's two oxygens bonded to the carbon one with the double bond and that's of course another level of oxidation and the final level of oxidation would be that carbon is double bonded to two different oxygen molecules so let's let's label this as a trend for you to remember is that the further down that we go right here like this so this would be oxidation let's label this oxidized so this is oxidized this is oxidized this is not oxidized this is reduced so it the opposite of oxidation would be right here going upward that would be reduced so right here we can tell if we're just looking at the molecules as they are right now right here the ch4 i can easily say that it is reduced because it has a it has a full octet with the ch4 and has four bonds two hydrogens no bonds to oxygens now if if we're going down all the way to here let's say the carboxyl group right here i can say that this is oxidized because the carbon does not have the maximum amount of bonds it could have to the hydrogen in fact it has no bonds to hydrogen it is double bonded to an oxygen and one bond to another oxygen and the other bond goes to the carbon so it it has no bonds to hydrogen which is therefore could be said that it is oxidized because it therefore it has lost electrons to another atom now here the electrons are fully present within the carbon because it is attached to four hydrogen molecules so now let's take a look at a couple of of examples of where these reactions actually occur so first we're going to take a look at this molecule of nad plus which becomes nadh and we must figure out which one is reduced which one's oxidized and where is the transfer of electrons now this ah2 that's simply uh another organic compound it could be an acid or whichever compound it is we just count it as a it's it's not important to us what's important is the hydrogens the the protons that will be transferred so first here the uh inorganic molecule is going to transfer two electrons and one phosphate to the nad plus then what happens is of course as you can see the charges are going to balance out so positive positive that's two plus and then two electrons is two minus so that's going to balance out to being neutral right here and it forms a molecule called nadh now on the other side the other hydrogen will be transferred here so the h plus would be just transferred over as its inorganic hydrogen that would just be floating around and so which one is oxidized and which one's reduced well if we know that oxidation is the loss of electrons then what we're going to have is that this ah2 molecule is oxidized so it's oxidized and the nad plus which has gained two electrons and a proton is going to be reduced so this is reduced so let's take a look at a couple more examples that occur in biological systems and the first one here is um is step 6 of glycolysis so this is this is the second part of glycolysis that actually gives off energy we actually get atp and nadh from the second part of glycolysis and this is the first step so there are 10 steps in glycolysis and step number six which is the first step of giving off energy is a redox reaction this is the first redox reaction in glycolysis so this is step six of glycolysis and what we got here is the molecule of glyceraldehyde three phosphate i'm not going to write it down because it's not important the the molecule names and you're gonna learn all of these when we go through cellular respiration however this molecule is in step six of glycolysis called called uh glyceraldehyde three phosphate because the phosphate is on the third carbon group right here now we are adding on another inorganic phosphate the one right here this is pi inorganic phosphate so this phosphate is simply flowing around in the cytoplasm as glycolysis is occurring and it comes on and it's going to attach onto carbon carbon 1 and it becomes 1 3 bis phosphoglycerate and the name comes again from the attachment of phosphates onto their respective carbons so this phosphate inorganic phosphate would attach to the carbon one and this one attaches to carbon three therefore it's called one three bis phosphoglycerate and what what happens is this whole reaction undergoes loss of electrons and gain of electrons so here whenever you see an nad plus being formed into nadh this is automatically a reduction reaction so this is reduction and how do we know automatically that this is reduction reaction well because the nad plus is going to gain two electrons and a hydrogen atom with a positive charge so proton two electrons and the proton onto its its molecule and it becomes nadh this is the nadh is the reduced form and nad plus is the is the oxidized form and it goes from oxidized to reduce therefore it undergoes reduction because it has gained two electrons here now if this has gained electrons then this molecule must have lost electrons and this is why we would say that the molecule right here would undergo oxidation while this one here undergoes reduction and another example and this is the overall reaction of cellular respiration and in reverse it is the overall reaction of photosynthesis and both of these processes we're going to talk about in great detail in the upcoming videos but here what we got is we have our glucose molecule c6h12o6 and the glucose molecule will be oxidized so we go on to here and it's going to be oxidation because it's going to lose electrons and of course it's also going to lose oxygen as well and what happens with the other molecule our oxygen is that it's going to be reduced so here we undergo reduction so these are some of the common examples and we'll be going through redox reactions in the coming videos when we're learning about photosynthesis and cellular respiration and glycolysis which have plenty of redox reactions specifically when we are having an uh an electron carrier being reduced to its final form here so that'll be the end of today's video and in the next one we're actually going to begin with the process of photosynthesis and all the reactions involved in it [Music] you