hello you guys um we've made it now to the last set of notes in unit one these are the unit 1.3 notes and these notes we're going to look at um enzymes in a lot more detail uh We've we've mentioned enzymes a few different times throughout some of the previous videos but in these notes we're going to look into a lot more detail and go into a greater depth of what these enzymes look like and what they're doing and um their their function inside of living organisms this these set of notes are made up of three topics which are each pretty short actually and so each of these three topics should hopefully not be pretty quick and easy to go through in this video we're going to look specifically at topic one where we're going to focus just generally how enzymes work in general um and so let's take a look at that so uh uh if you remember or recall when I've brought up enzymes before I told you guys that what enzymes are doing is they are catalyzing chemical reactions meaning that they are allowing certain chemical reactions inside of your cells to to take place fast and quickly and efficiently um that's that's the job of an enzyme and these enzymes they're they're proteins so these are these are proteins that ultimately take on a specific shape and their job is to uh allow these certain reactions to take place inside of your uh your cells and so let's do a quick refresher on chemical reactions so chemical reactions um just to remind you guys these um this is when um you're you're taking certain molecules and those molecules are being turned into new molecules through chemical bonds being broken between atoms and then reformed between atoms in a different way to make these new molecules and so ultimately you're taking certain molecules that you're starting with and those atoms that are found in those molecules they're bonded together in this case usually by covalent bonds or bonding these atoms together of these different elements and these starting molecules um and then the chemical reaction what's going to happen is we're going to break those bonds apart we're going to take those atoms and break them apart from each other those bonds and then we're going to form new bonds between them so that we end up with new molecules so that's basically what's happening in a chemical reaction so here's an example with photosynthesis taking these starting molecules six carbon dioxide molecules and six water molecules ultimately are going to be used to make a glucose molecule and six oxygen molecules but that's basically just taking these atoms and then breaking them apart in these starting molecules and then putting them together in a different way forming new Bonds in these these new molecules now in a a chemical reaction well chemical reaction we summarize it with a chemical equation so this is called a chemical equation and so is this right here it's showing you basically a summary of what's taking place from beginning to end now the chemicals that are shown on the left side of the arrow those are called reactants so reactants are the molecules that you're starting with at the beginning of the reaction and then on the right side of the arrow you have What's called the products and these are the chemicals that we're ending with once this reaction is is done and so and then one more thing that we need to talk about before we get into enzymes is this uh this idea of Act of activation energy and so um every chemical reaction that exists has what's called an activation energy and so activation energy is this certain amount of energy that the starting molecules need to get to so whatever molecules are starting with there's a certain amount of energy that they initially need to absorb and get to in order for them to then be allowed to become these new products during the chemical reaction in order for the reaction actually happen and for those molecules to now become these new molecules and so that that initial amount of energy that the reactants need to absorb that's called the activation energy and every single chemical reaction that that takes place in the universe has has an activation energy if you look on this graph you kind of need to be familiar with a graph that kind of looks like this this should look a little familiar from chemistry but this is called an energy diagram and it's basically summarizing the the the change in energy that's taking place in a certain chemical reaction so in this reaction we're starting with these molecules these are just made up molecules this molecule a b and this molecule CD those are the two starting molecules and those molecules have a certain amount of energy to start with so molecules innately have a certain amount of energy just inside of stored inside of their their chemical bonds and so this y-axis is showing you how much energy they're starting with they're starting with this much energy now ultimately in this reaction they're going to become these new molecules molecule AC and molecule BD and those new molecules have a certain amount of energy and you guys can see in this case the amount of energy they have is less than the amount of energy the starting molecules had which which happens sometimes sometimes the molecules you end with have less energy than the molecules you started with sometimes they have more energy than what you started with but what is really important on here right now is this bump and so in order for these reactants to become the these products there's going to be this certain amount of energy that they need to climb up to that they need to absorb so the amount of energy that they have innately is not good enough they need to get to the certain amount of energy first in order for this reaction to actually happen so that they can become these new products and that is what we're looking at here that's the activation energy and look very carefully at this graph how it's labeled because this will come up in future questions that I ask you guys but uh it's it's the energy that you're starting with in the reactants and the amount of energy they they need to get to the top of this bump up here on the y-axis so going from here to here so that's why this arrow is labeled the activation energy says Arrow represents the amount of energy that these reactants need to absorb in order to get to the top of this energy barrier to get the amount of energy they need for this reaction to take place that's the activation energy be careful because a lot of students think that it's like from the bottom of this graph like from down here all the way up to here but that's not the activation energy because you're already starting you're not starting with zero energy you're starting with a certain amount of energy in these reactants which is this dotted line right here that's how much energy you're starting with and you need to get to the top here of this bump so that's the activation energy for this specific reaction shown in this diagram and every chemical reaction is different it has a different amount of activation energy that's required some chemical reactions have a very um large activation energy so they have a huge bump there's a lot of energy that the reactants need to absorb and for in order for the reaction to take place and for those reactions the ones that have a large activation energy if reactions have a large activation energy that means that that reaction is going to take place very slowly it means that that reaction is it's going to be very hard for that reaction to take place because there's so much energy the reactants need to absorb in order to get to that energy they need to get to and so reactions with large activation energies occur very slowly now if you have a reaction that has a small activation energy so in a different reaction let's say that there's a very small bump there's not a lot of energy the reactants need to absorb there's a small activation energy that's going to be a reaction that can take place a lot easier more easily and so that's going to happen a lot faster those reactants are very easily going to find and absorb the energy they need to get to because it's not a lot of energy they need to get to in order for the reaction to take place so just know that reactions with lower activation energies are going to occur more quickly or faster and usually this energy there is coming from the the um usually the the Heat or thermal energy that's around these molecules they can absorb that thermal energy from their surrounding and use it to get to that energy they need to get to in order for those reactions to take place now this leads us finally to enzymes and what they're doing and so an enzyme is a protein again I want to emphasize that enzymes are proteins um that are chains of amino acids that fold them into a specific shape and they these are specifically proteins whose job is to catalyze reactions or act as Catalyst in um inside of your cells in living organisms now a catalyst this is a chemistry term a catalyst just generally refers to any substance that allows a chemical reaction to go faster that increases the rate of a reaction and it's doing that by lowering the activation energy so because that substance is there that activation energy actually becomes a lower when that that catalyst is present the reactivation energy is lower and that is going to allow the reaction to happen more easily which is going to result in the reaction happening faster because the activation energy is lower and so that means the reaction is going to happen more easily that's what a catalyst is doing and so enzymes they're exactly that enzyme times are Catalyst they are lowering the activation energy for chemical reactions which are going to allow these certain reactions inside of your body to happen more quickly because now it's easier they don't need as much energy now um and so uh that that's what we see in living organisms we see these enzymes which are acting as Catalyst inside of cells on this planet allowing chemical reactions to take place way faster than they normally would had those enzymes not been present and so if you guys look at this graph I just want to point out like this black line represents the that's kind of like showing the reaction without an enzyme and so you're starting with this much energy you're ending with this much energy and the reactants and the products but the bump you can see the bump um the activation energy without the enzyme would be this Arrow right here you need to go from this starting amount of energy to the top here so this is the amount of energy you need to absorb according to this diagram without the enzyme now look what happens with the enzyme let's say the enzyme is present and so now there is an enzyme present in this chemical reaction we added an enzyme and that enzyme what it does is it it's represented by this red line here it's going to lower that bump that's all it's doing it's lowering it's not changing how much energy you start with or how much energy you end with it's just lowering the activation energy the the energy barrier that you see on this graph so now instead of needing this much energy you only need this much energy which will result in this reaction happening faster because it's going to be easier now for those reactants to get to the energy they need to get to in order to become these new products so that's that's ultimately what enzymes are allowing to happen inside of your cells now in terms of their their structure enzymes like I said these are proteins which are chains of amino acids all these different amino acids that were bonded together and those that giant chain of amino acids it folds up into its primary secondary tertiary structure and so you have this folded up polypeptide that takes on a very specific shape um and that uh that shape is going to be ultimately what allows so here's the let me move my little picture here um that that protein is going to fold up into a very specific shape kind of represented here or down here even and um that shape is what's going to allow it to catalyze specific chemical reactions inside of cells and so uh let's see where should we start let's start with the fact that um so uh and so this shape that the enzyme takes on it's going to have a very there's going to be a very special region on the enzyme shape called the active site and this is where all the magic is going to happen the active site so this is a special part of the enzyme shape and this part is important because this is where the enzyme is going to find those starting molecules and bind to them it's going to physically latch on to these starting molecules these reactants these molecules you're starting with and then by finding these molecules these are reactants and binding to them the enzyme is then going to allow those molecules to more easily become products once it grabs onto them and helps them out and so those reactants are going to bind here to the active site and when we're talking about a reaction that's catalyzed by an enzyme those reactants we call them substrates so a substrate is the re reactants that an enzyme is binding to so like if this enzyme was helping this reaction take place right here then the reactants would be the substrates would be CH4 and O2 those are the the molecules that those are the reactants that the enzyme needs to bind to so the reactants those are called we call them substrates that's what the enzyme is going to latch onto so that's the starting molecule the molecule you're starting with um which is going to bind to this active site now when it binds to the active site it forms what's called an enzyme substrate complex so here's the enzyme this purple blob here are the substrates the reactants the starting molecules that it's going to bind to and it latches onto them and enzymes they when they latch onto substrates they they form what's called a induced fit which is when the enzyme changes shape a little bit once it binds to the substrates and it changes shape just slightly in a way that kind of Embraces and latches on to the the substrates basically so that the substrates don't easily fall off before the reaction is done and so you guys can see here's the enzyme to start with but once it binds to the substrates you can see it takes on a slightly different shape once it binds onto those substrates and this is going to help it keep hold of those substrates and then something magical is going to happen where now those substrates can re interact with each other and form these new products the these bonds are going to start breaking and reforming and then they're going to become these new molecules and then once that happens the enzyme will let go of them and now you have these these molecules you're ending with and so uh basically that's that's how these enzymes are catalyzing these reactions they're binding to the reactants the substrates and then allowing them to become products and then that enzyme can then um redo that over and over and over again because during this reaction if you look at this picture this purple blob um is not actually being changed or used up during the reaction so from beginning to end this enzyme is staying the same so it's it's helping the reaction take place but it's not actually part of the reaction um the substrates these chemicals are changing into new chemicals products but the enzyme itself is not chemically changing and it's not being used up it's not like a one-time thing so these enzymes they can they can catalyze a reaction and then do it again and again and again and again um so which leads us to the end of topic one uh which is this idea that enzymes are are very specific so enzymes have a very high specificity which means that they can only catalyze very specific chemical reactions um and so there's there's only one reaction that they can help out with and that's it there's not a bunch of there's not all these other reactions that that enzyme can also help out with it's only a one type of reaction that that enzyme is responsible for so inside of cells there's thousands of different enzymes being made and each of those enzymes are controlling their their own very specific thing um and it's very very very specific I'll give you a couple examples in a second but basically the reason it's so specific is because enzymes have a very specific shape that they're folding into with a very specific active site and that active site can only bind to a very specific substrate and there's not a bunch of other chemical tools that it can bind to only a very specific molecule or molecules that it can latch onto and so those substrates they they bind to the enzyme so here's an example of a substrate of the starting chemical and then here's the enzyme in its active site that active site has a shape that's compatible with the substrate but it also has certain chemical properties that are also compatible with the substrate so what's going to happen is when the substrate binds to the active site there's certain weak interactions that are going to form between the substrate and the active site that are going to help them bind together and those weak interactions include things like ionic bonds that some enzymes can form with their substrate some of them form specific hydrogen bonds with their substrate or some of them have polar or nonpolar interactions that are taking place that are allowing them to to come together or bind with one another and so these weak interactions are kind of allowing the enzyme to temporarily hold on to the the substrate so to summarize every enzyme has a specific active site that has a specific shape and a specific set of chemical properties that allow it to form these weak interactions with a a specific substrate and so that's why the these enzymes can only work with certain chemical reactions and so for an enzyme mediated chemical reaction to occur it's saying that the shape and the charge of the substrate the shape of this substrate and the chemical properties of this substrate like it's its charge and ability to form hydrogen bonds and its polarity all of that needs to be compatible with the the active site of the enzyme in order for this to work and so here's a couple examples of how specific these enzymes are just to give you guys an idea so here's an example with lactase so lactase binds to this um this disaccharide called lactose so lactose is a disaccharide it's a carbohydrate it's a two monosaccharides bounded together this is a the sugar found in milk and so there's these two monosaccharides bonded together it's called one of them's glucose and one of them is galactose so here's a disaccharide we talked about this in topic one of the last set of notes and it can bind to lactose and then by binding to lactose it actually helps catalyze the reaction that breaks them apart there's a hydrolysis reaction that breaks the bond between them and so now you have glucose and galactose separated from one another and this can now be easily digested into your body with the help of this enzyme now that lactase like I said is is very specific and only can do that reaction so here's an example where it can't help out like here's maltose maltose is also a disaccharide but it's made of two glucose this is glucose and glucose bonded together but it's also a disaccharide but this disaccharide it can't break the bond between these two monosaccharides so lactase can't do anything with maltose and that's because lactase is very specific and can only catalyze the reaction of this very specific disaccharide breaking down into two monosaccharides it can't take this different mono disaccharide and break it apart or here's one last example this is amylase amylase is an enzyme who breaks the the bonds between glucoses and starch so in starch is a polysaccharide found in plants it's used to store energy we talked about this also in the last set of notes but this enzyme can break these glucoses apart and starch but cellular lows which if you guys remember cellulose is also found in plants it's a polysaccharide kind of plants and it's also made of a bunch of glucoses but amylase cannot break these glucoses apart so here's another interesting example where it's just a bunch of glucoses bonded together in starch and a bunch of glucose is bonded together in cellulose but in starch amylase can break these bonds but in cellulose it cannot break these bonds because it's very specific and that has to do with the glycosidic linkages between them if you guys remember there's two different versions of glucose the alpha and Beta glucoses And so in starch there's a certain pattern of these these bonds between them that amylase is compatible with but it's not compatible with this pattern of bonds found in in cellulose and so again just now enzyme is very specific and uh the the the name of an enzyme so enzymes have names and that name usually um is referring to how specific that enzyme is and so the the name of an enzyme always M ends with the suffix Ace most of the time almost all the time there's some exceptions but usually when you guys see a word that ends with Ace like lactase or ATP synthase or amylase these are these are enzymes enzymes the the ending of their name ends with Ace and their name usually refers to the substrate that they bind to are the type of reaction that they catalyze so like I said lactase well he binds to lactose that's hence his name um and then there's another here's another enzyme called ATP synthase ATP synthase is an enzyme who catalyzes a reaction that makes ATP so his job is to synthesize ATP so hence his name is ATP synthase that's the reaction that he's doing um but yeah that's basically it for topic one uh so uh hopefully that all makes sense so far anyway I'll see you guys later um and please watch the videos for topic two and three