for so midterm is coming up divide that we'll get a midterm grade and pretty quick are you guys are the calendar okay I'll keep reminding you yes about registration that's weird let me see the Gibbs free energy right we were talking about changes in free energy okay so we remember that our let me get a different color the free energy is Delta G so G is the gives free energy and that's um here the change in h which is the total energy right in the in the system minus what we're going to lose to entropy remember we always got to pay entropy so an entropy is calculated by the temperature times Delta s which is the change in entropy okay so this is the gives free energy equation okay so when we know the Delta G of a reaction that can tell us a lot about what's going on okay and everybody remembers for a chemical reaction we have reactants and we have either one product or multiple products and the reaction can go backwards and forwards in both directions okay so all right so we have to so if we want things to move only in One Direction which we do in the cell then we have to somehow stack the deck in our favor to make sure we never have the reverse reaction happening all right so let's take a look at some graphs that are showing us what's happening in a reaction okay so on the Y AIS this is the free energy so this is the energy okay you can think about it just as energy and then this is basically time okay over the course of whatever the chemical reaction is okay and so we have reactants and products okay so we have our reactants down here and we have our product up here okay which one has higher energy based on this graph the products right reactants are pretty low energy and what with the blue line is showing us is that we have to go uphill to get to the product okay so we're we're going uphill to do to get to those products to do this reaction we have to have energy to do it we got to put energy into the system okay so what kind of reactions usually are we putting energy into the system anabolic right who said that very good very good very good ab so these are these are going to be building reactions typically okay we also call them endergonic so this is a reaction that requires energy okay so we got to go uphill our reactants whatever their atomic structure is it has low energy they're typically typically when you have something that's lower energy it's really stable so it doesn't really want to change it's in a very stable state so to get it to change we got to put something in there to push it towards those products okay so we got that kind of reaction you can also have the opposite right so in this case who has higher energy the reactants right and we have our products down here that have lower energy okay and so this is a downhill reaction okay so in this case in a downhill reaction we don't need energy we're actually going to release energy in this type of reaction okay this is called an ex reaction okay so that would be equivalent to what type of General anabolic or catabolic catabolic reactions for the most part you'll see that not all reactions when we're breaking down glucose for example are really that um this different in between the reactants and products um so usually we have to we have them coupled in a in a series of reactions I'll tell you about that okay so this kind of feel the difference between the energy of the reactants and the energy of the products that change that is the amount of energy released okay this is the Delta G okay and for a reaction like this that is going downhill from reactants to products okay that's exergonic it has a negative Delta G okay and because we're going from high energy to low energy kind of down this energy H also happen typically spontaneously okay you'll also hear probably in more in chemistry that these are favored okay these are favorable reactions because they're going downhill we don't really have to do much right that make sense so if we go back and look at this reaction where we're going from low energy reactants to a higher energy product the Delta G for these reactions is positive okay okay so if we are looking at a chemical reaction usually you're given a Delta G so if it's positive or negative this is telling you about this reaction does it require energy or is it releasing energy okay is it favored in the case of negative Delta G or is it unfavorable where it's positive Delta G spontaneous or nonspontaneous so you'll hear all these terms applied when you talk about changes in free energy okay that does that seem pretty clear because we're going to be looking at a lot of different chemical reactions okay to make sure everybody understands this concept of Delta G the change in energy right so the Delta G is the energy we have available if possible to do work okay all right so we've already talked about this equation this is the uh gives equation for free energy right and Delta H is H is the total energy what we lose to entropy right entropy is the energy we cannot capture to do work the energy that's available for work okay does that make sense okay so this equation is pretty straightforward understand the components pretty easy okay and the only thing to that I'll remind you about because I'm sure you're going to do um calculations with this in chemistry don't forget that the temperature is always in kelvin okay I'm not going to ask you to do equations but I'm just reminding you because I know your Chemistry professors are going to ask you to do that okay so now if we kind of look back at our anabolic and catabolic reactions you can see exactly what you guys found from you know what you guys um eluded from the from the graphs an anabolic reaction is going to have a positive Delta G and a catabolic reaction where we're releasing energy that we're going to capture in molecules so that we can turn it into ATP that has a negative so when we talk about taking sugar glucose to CO2 in respiration you're taking something has high energy right and we're turning it into carbon dioxide and water which have low energy so carbon dioxide is the lowest energy form of carbon that you can get you basically stripped everything out of right so if we need energy we talked about this we have our buddy over here ATP where is the energy stored in ATP in the phosphate bonds that's right very good okay so we're going to have to hydr those bonds we're going to have to hydrolize those calent bonds okay so it's a hydrolysis reaction right so this is just showing you what this looks like so this this is our energy that we can used to do work so you know T typically you know ATP is not just being uh hydrolized in the cytoplasm okay it's it's in an enzyme so it's in a confined area where that bond is being broken and you can use that use that energy can be captured and used to form other bonds or form a new product okay so ATP is not just like hanging out in the cell being hydrolized randomly you need an enzyme for that the other thing know we talked we've talked about every every time we make an energy change or any reaction we have to pay a little bit to entropy right so if you look at this we're going from ATP which is you know one thing two two different things over here we've got an molecule of inorganic phosphate it's the phosphate group that we took off and we have adenosine D phosphate ADP so when you break something like that we now have more pieces that is considered less organized okay so that's we paid our entropy debt because we're going from something that is one thing organized into one molecule now we've broken it into pieces so it's just like if you took a vase and smashed it on the floor right you went from the base that was one thing to now you have thousands of pieces you have an increase in entropy in the universe okay so we paid our price to entropy okay and this reaction is this has a negative uh Delta G okay that makes sense all right so how many who remembers how many reactions are in glycolysis I've said it a couple of times anybody remember so that's 10 reactions 10 individual reactions going from glucose to pyruvate that's the final product of glycolysis okay so we have 10 reactions put together not all of those reactions have a PO have a they have not all of them have a negative Delta G some of them have a positive Delta G and some of them have like a really really small negative Delta okay so we don't want to move backwards from pyate to glucose we only want to move in One Direction okay so to do that those 10 reactions we consider them one thing okay they are coupled together so what you'll see when we talk about glycolysis is that there are actually three reactions of those 10 that have huge changes in free energy they have very negative Delta G's and because they have such a Negative free energy change they drive everything else in One Direction okay so that is what C is when you couple reactions and that's how the that's one of the ways the cell manipulates things to make sure that everything is moving in the right direction we don't get any kind of backward flow okay so even though some of the reactions might have a positive Delta g at the end of the end of the reaction the over we can add all those Delta G together so so these are additive so I can take those 10 reactions those 10 individual Delta G's and add them up to get one Delta G for glycolysis and when I do that it's negative that means it's going to go in the right direction it's going to go from the reactant to the product okay does that make sense some people yes some people okay so this is actually showing you um looking at some reactions that are coupled together so um obviously hydroling ATP is exergonic but glucose to glucose 6 phosphate is an endergonic reaction okay so it has a positive Delta G and this has the hydrolysis of ATP yes so for you have well I mean for glycolysis has 10 reactions but only three have a really negative Delta G the rest of them are just kind of they're they're they're they're kind of weak as far as the energy change okay so in that case we have three reactions that are driving the other seven to move in One Direction so it you know and every biochemical pathway you just have to look and see they all have very different steps um and so you know you can have a few or you can have all of them may have a negative Delta G it just depends on the reactions you're talking about okay so this is glucose to glucose 6 phosphate we talked about that reaction what reaction is that in glycosis taking glucose from the bloodstream we moving into the cell and it's glucose becomes glucose 6 phosphate so that's the first reaction of glycolysis right we start with glucose in glycolysis right and you can see it has a positive Delta G okay why do you think that is why do you think it has a positive Delta G what so look at what you're M what do you what are you going we're going from glucose to glucose 6 phosphate right so the reason it has this positive Delta is that glucose 6 phosphate is more energetic than just plain old glucose phosphate groups are very reactive they add a lot of energy okay so that's why it's going uphill that's why has a positive Delta G so it's it's a positive 3.3 kilo calories per mole but when we hydrolize ATP to do this reaction it has a negative Delta G of 7.3 so we can add these together and overall we have a really nice negative Delta G for that coupled reaction okay so this is the first reaction of glycolysis this is the last reaction so this is reaction 10 we're going from a called phosphino pyruvate to the final product which is pyruvate okay so this reaction has what that negative Delta G so what does that [Music] mean do we need energy for that no right it's it's releasing energy okay but you'll notice that this is actually a beneficial reaction for the cell because in this case we actually add a phosphate back to ADP to make ATP right so this is one of the places in respiration that we actually make a little ATP for ourselves but you notice that so we know the hydrolysis reaction has a negative 7.3 kilo calories per mole so the reverse reaction is a positive 7.3 kilo calories per mole so that's an uphill reaction making ATP okay and you'll you can see how large that free energy drop is going from phosphino pyate to pyate minus 14.8 kilo calories per mole okay this is actually one of the three reactions that drives everything towards py so we couple that to forming a new molecule of ATP and add it together we have a negative Del that reaction so phosphino pyruvate is a high energy molecule and it actually directly donates its phosphate one of its phosphates to um ADP okay that's something called substrate level phosphorilation okay which is a part of glycolysis that we'll talk about does that make sense to people yes no you guys look really tired wild parties over the weekend I'm guessing party after the game try to hang on she all right so I'm not going to beat a dead horse here we've looked at this okay you can add when you have a pathway you can add all those Delta G's up to get an overall Delta G for whatever that pathway is and that's true all the time I was telling you about when we talked about ATP last time we talked about how it was kind of kind of in the middle it wasn't super high energy but it also wasn't low energy it's kind of in the middle of the energy range and this is showing you sitting in that kind of in that middle region so phosphopyruvate is what we call a high energy molecule and that's because it can actually give its phosphate to something else which is unusual there not a lot of molecules that can do that okay glucose 6 phosphate on the other hand is pretty stable and so it has a lower energy so ATP can we can can accept know you can go downhill so phospholine on pyate can phosphate can phosphorate something down energy from it ATP can give energy down from itself but you can't go from glucose 6 phosphate back up okay you can't do the reverse unless you have an enzyme or something something else is going on okay so downhill you can do it uphill you can't so ATP has this intermediate Delta G right in the middle and that's because we want it to be an intermediary uh between these high energy molecules and lower energy molecules okay all right before I move on to talk about enzymes everybody seem seems okay right now it's it this is harder material I'm not gonna lie this this exam is harder it's more chemical it's a lot more chemistry and it doesn't come as easily homor when [Music] you're down questions and bring them and ask them because if you have the question promise you probably 10 or 15 other people have it yeah Abby for real that I love it let me go back to the yeah so this is a this is a go to the reaction yeah so well it can reverse sure because the products have higher energy so if they were just kind of left alone if we just had the products and the reactants yeah and reaction goes both ways so yeah it can you could have them going downhill uh but in these cases but the other thing the cell does to keep this from happening is there these are mediated by these reactions are mediated by enzymes okay the enzyme makes a big difference too because it's a catalyst and it's helping this reaction along without the enzyme well without the enzyme the reaction isn't going to take place at all right because we just put the reactants and the in a beaker and let it sit nothing's gonna happen because they're low energy right even but even if we took the products and put them in a beaker it would take a long time for the reactants yeah because basically you have to you're waiting for the products to somehow spontaneously break apart and that who knows that that could take years decades hundreds of years depending on what we're talking about so it's that's what's that's another thing that's really important in the reactions in our cells that we have enzymes that mediate these processes so they take place in a timely manner right otherwise they wouldn't and that's not going to work out for us we got to have things moving does that make sense okay so think about this a little bit when you're doing your homework you know when you have questions bring them to class okay so we can can talk about them and we'll we'll we'll do some practice questions as we go along all right all right so let's talk a little bit about enzymes all right so enzymes are proteins right most enzymes have a globular kind of rounded shape most enzymes have that shape so they're folded they have lots of intricate pockets and crevices that form active sites okay so this is showing you in a catabolic re reaction so this is a different way to that we show reactions you have these are the reactants and so in this case because we have an enzyme we say we have the enzyme and S is for substrate okay that's the same thing as the reactants we have a lot of terminology we of use interchangeably here in chemistry right so the enzyme can bind those substrates it has a very specific place to bind them okay that absolutely just fits them okay when they bind you form something called the enzyme substrate complex okay when you form this what happens is when they when you get the substr bound the enzyme kind of hugs down on the substrates okay you can actually see this change when you look at atomic structure and what it's do what the enzyme is doing is it's actually putting strain on those substrates it puts strain on the bonds squeezing them that makes the bonds break and now you can form the product okay so this is this how this is one of the ways that this is how enzymes actually facilitate reactions make them happen quickly okay so you go from enzyme substrate to enzyme product so this is the chemical reaction okay this is just binding this is just getting the substrates into that active so the pocket where the substrates bind is called the active site okay once you get the enzyme product complex the products are released okay and it happens very fast and that's because the products don't bind to the enzyme as well as the reactants okay and you'll notice we get back we have our products we get our enzyme back the enzyme is not used up it's not destroyed there it's it's ready to do this reaction again are you guys okay back there so you have an intact enzyme that can actually be essentially recycled okay so when we when enzymes are mediating reactions they're not destroyed they're not used up in the reaction okay they're just constantly being recycled to do that reaction over and over again right the same thing happens in an anabolic reaction you just have to put energy in to get this to happen Okay so you still have substrates that are going to react that are going to bind the enzyme you'll form the enzyme substrate complex when they're bound that's going to put strain on the bonds of the reactants and you'll move to the product and the product is rele so and again the enzyme do not changed okay so let's talk about if we look at kind of the nitty-gritty of what the enzyme is actually one of some of the things the enzyme is actually doing to make this change from substrate to products move quickly so this graph is the graph you're going to see a thousand times showing you the progression of a reaction Okay so AIS we're going to have Delta G this is time on the X AIS we have our reactants over here we have our products so in the last set of graphs we just had our reactants and products going and all we really saw was this the free energy change right we didn't see this part over here okay every reaction has it doesn't matter if it has even if it has a very negative Delta G there's always sort of a initial energy that has to be kind of put in for the reaction to get going okay this is called the activation energy every re action has this I don't care what the Delta G is okay so there's always going to be this little energy Hill at the top of the energy Hill is this very reactive molecule called the transition state so this is an intermediate between the reactant and the product it forms instantaneously and it's gone just as fast so you cannot we cannot um isolate transition St okay if you look at the blue line is this reaction whatever it is without an enzyme okay so okay red of crimson over here go over here this is the reaction with an enzyme okay what do you notice what is the difference between the blue and the red line that's right Co the red has a lower activation energy the little the h is much smaller when we have our enzyme than when we don't have it okay so enzymes lower activation energy right so they take those reactants in they put them in a confined space that wouldn't be there if the enzyme wasn't there the enzyme closes down on those substrates putting Bond strain on there okay that makes you get to the transition state very quickly so now you're that's what's making your heel really short very small and then once you get to the transition state you immediately don't no matter what reaction go from the transition state to the product okay so this is how enzymes work okay so they're acting to facilitate the reaction and make it move faster okay now what doesn't change is the delt it doesn't matter that the enzy is there of the Rea en not so adding an enzyme does not change the Delta G of problem you can't you don't change that Goodbody that all right oh yes sorry Riley it's always going to look something like this it is different depending on what the reactants are so you know the activation energy is different for every reaction but it's you're going to have the same shape so there's no change in that does that make sense all right so when we add an enzyme what we're doing is we're bringing down that activation energy that makes the reaction go faster okay so adding an enzyme increases the rate that the reaction happens it makes the reaction happen faster it doesn't change the Delta G okay and the whole reason it goes faster is because you lowered the activation energy right you don't have to go up as far to get to the transition state right makes sense does that seem okay all right so we talked about when we talked about protein structure remember you have to fold the protein to make it work it's not functional if it's not folded so it has to have at least tertiary structure to be functional when you fold enzymes you can see that they have an active site right and this is where the substrates will bind okay so and enzymes are very specific okay there there are most enzymes only bind a certain number a certain pair of sub pair of substrates or a substrate and they go to one product they don't they're very very specific because these these active sites have a really specific structure that is made to fit whatever that substrate is okay so enzymes are quite specific right so you can see that that substrate especially in the molecular model you can see that bound very precisely within that active site okay the enzyme actually has that molecule set so that the reaction takes place appropriately because of the binding okay you got to have protein folding for active SES Okay so unfolded doesn't work right so what kind of what kind of what level of structure is this when it's unfolded you just have a string of amino acids that's primary structure and then what about let's just say this is a single subunit protein folded what level of structure is that tertiary if it had multiple subunits what would that be portinary structure this is tertiary okay remember that from our last chapter we talked about okay let me skip that okay so this is kind of looking at an enzyme substrate complex so we're going to there is an enzyme called beta galactosidase so enzymes tend to have this ASC tacked on the end of them so you can always recognize okay so the enzyme beta galactosidase breaks this sugar bet gide okay now this is a relative of beta galacti side similar very similar structure but you can see it has a sulfur right here okay so this is actually interesting because because of the structure of the sugar the enzyme beta galactosidase can bind it but it just stays there it can't cleave it because the shape is not right okay so it's not enough that the substrate combine actually this is a this is the way we design in Pharmacology we're Des designing drugs that are Inhibitors we design something that looks like the actual substrate but it binds to the whatever the enzyme is that we're trying to inhibit and it keeps it from working okay so a lot of a lot of um in in biology of cancer we're talking about a certain class of pharmaceuticals are called protein kinas Inhibitors so this is where we uh far theologists have actually developed molecules that will bind to these protein kinases that mediate really important reactions in our cell and stop them from working okay because in cancer they tend to be mutated and they turn these pathways on all the time especially related to cell division so now you have a cell that's just dividing without any controls and that's not good okay does that make that make sense kind of shows you that enzyme specificity that active site is very specific all right I'm going to stop right here and we're going to take our quiz you can use your notes you can use your if you brought your book