uh what we have to cover here is uh what are enzymes basically now before we talk about enzymes though I just want to give you an example of a situation all right okay in Chapter 2 you learned about something called starch there were two types of starch molecules Amo and amop pactin and I'm drawing out an amose molecule over here as you can see amilos is just basically made up of many alpha glucose joined together by something known as Al Al 14 glycosidic bonds all right so let's say for example we want to break the glycosidic bond to break the alpha one for glycosidic Bond we need to carry out a reaction known as hydrolysis and what is hydrolysis by the way hydrolysis just basically means using water to break the calent bond in this case to break the glycosidic bond so I'm drawing out a water molecule over there represented as h 2 now if the water molecule were to just daintily go and touch the glycosidic bond just touches it uh will the water molecule break the glycosidic bond or does adding water immediately break the glycosidic bond the answer is actually no you see water cannot break the glycosidic bond immediately so okay if okay consider this situation then if you were to to take rice all right which contains a lot of starch by the way and if you were to just immediately add water to the rice will will the starch inside the rice just break down and become glucose immediately no it it does not so you might be thinking to yourself wait a minute have I been lied to because in Chapter 2 you were told that to break these covalent bonds such as glycosidic bonds you needed to carry out something known as hydrolysis which is using water so were you li to well no you were not Li to exactly you see to effectively break the bond you first need to weaken it all right you need water to break the glycosidic bond but the glycosidic bond is too strong and by just adding water to the bond it's not going to cut it so the water needs to effectively collide with the glycosidic bond at an extreme ex high energy level or at an extremely high energy always compare this to a situation I always tell this to my students you have your hand and you have a glass window all right if you were to just touch the glass window will it break it no it won't okay you have to use your hand and punch the glass window at a certain energy level or certain kinetic energy to break the glass window by the way please don't do that okay I'm just giving a comparison I don't want students to start breaking glasses all right it's just a comparison so uh same thing with water too if the water is to effectively break the glycosidic bond the water needs to hit the glycosidic bond at a high energy level so to effectively break the bond you need water but you need to heat the water up and increase its kinetic energy and hopefully it will bash onto the glycosidic bond and break it right but that's the thing so if you were to eat starch and the starch goes into your body are you then what are you supposed to heat your body up to a very high temperature no you can't heat your body up to a very high temperature and you'll turn into ashes all right so that's just not feasible that's not a practical approach to break glycosidic bonds when you eat rice for example or when you eat pasta um so in that case what you need to do is you may need to weaken the bond with a biological catalyst such as an enzyme so I'm just throwing an enzyme over there and what the enzyme actually does is the enzyme so uh so immediately students will go aha the enzyme breaks down the bond for us no the enzymes do not break down the glycosidic bonds all the enzyme does is the enzyme weakens the glycosidic bonds so that it's easier for the water to break it down so that's what uh enzymes are supposed to do so that's just an introduction to what why an enzyme is important so coming back to the question what exactly are enzymes then uh enzymes are first and foremost globular proteins and if you remember in chapter 2 globular proteins are basically proteins with 3D structures they can be tertiary or quinary depending on the situation they are spherical in shape okay I'm going to link uh a video Bel in the description so you can go back and do your on globular proteins and they are also water soluble because they can interact with water and enzymes are basically known as catalysts now what exactly is the meaning of catalyst so catalysts are just basically molecules or substances which make it easier for the reaction to take place let's just understand that as the definition of catalyst for now I will elaborate on that later but for now that definition is good enough so for example if you have water molecule trying to break the glycosidic bond in the starch will it be able to break it no it won't it just can't break the glycosidic bond because the glycosidic bond is too strong to break down but with the help of an enzyme that weakens the glycosidic bond on the right hand side the water molecule can easily now break the bond and therefore hydrolysis can happen now the amount of energy needed for the water to break the bond all right on the left side it needs a lot of energy you need to give the water a lot of energy so that it's able to break the glycosidic bond that energy is referred to as something known as activation energy by definition the energy required for the reaction to take place but with the help of the enzyme do you need to give the water a lot of energy or does it need to achieve that high amount of activation energy no it does not have to because with the help of the enzyme the enzymes actually weaken the bond therefore the activation energy needed to break the glycosidic bond is much lower enzymes make it easier for a reaction to happen by reducing the activation energy for a reaction to occur all right that's what enzymes do so then comes the question so why are enzymes so important in life like what's the big deal about enzymes like why do we need enzymes so I'm just basically drawing out a human cell here uh remember just a bit of revision for chapter one you can see the nucleus right there in the middle you can see ATS ribosomes on rough ER uh how do we know that's the rough ER because it's a single membrane or organel with interconnected membranes uh you also see the mitochondrian on the right side uh the one in red and the mitochondrian has a double membrane where it has a smooth outer membrane and folded inner membrane that's just a revision okay so the function of ribosomes on the rough ER are to synthesize proteins by joining amino acids together the mitochondrian carries out aerobic respiration where they break down organic molecules such as lipids and even uh pyro I'll explain this in Chapter 13 to synthesize a molecule known as ATP an important energy molecule and in your nucleus your nucleus carries out a very important reaction known as the synthesis of DNA now based on the list that I've written here within just one cell we have four different types of chemical reaction synthesizing protein is one chemical reaction breaking down lipid is an chemical reaction synthesizing ATP is a chemical reaction and synthesizing DNA is a different type of chemical reaction all these chemical reactions cannot happen without the assistance of enzymes and you need to have different types of enzymes to actually uh carry out these chemical reactions in the cells for example to synthesize protein an enzyme known as peptidal funas is needed to synthesize ATP you need an enzyme known as ATP synthes to break down lipids you need something known as eil COA dehydrogenase and to synthesize DNA you need two different types of enzymes known as helicase and DNA polymerase immediately students you might go do I have to memorize all this no you don't have to memorize all this you will be introduced to some of these enzymes in the future for example helicase and DNA polymerase will come back to haunt you in chapter 6 uh ATP synthes will be in Chapter 13 of was it chapter 13 no chapter 12 of A2 biology all right but you don't need to memorize all these enzymes right now the point I'm just trying to make is your cells carry out a lot of different type of chemical reactions and all these chemical reactions are assisted by different types of enzymes the interesting thing here that we know about all these different enzymes are their names end with the letter A at the back as e transfer a synth a dehydrogen a and polymer a and helicase I'm highlighting it over there so that you can see so that just gives you an idea that most not enzymes but most enzymes basically have their names ending with the alphabets ace at the back so long story short enzymes are just basically globular protein they reduce the activation energy how do they reduce the activation energy I'll talk about that later uh so they reduce the activation energy required for a chemical reaction to happen and they are important for biological reactions in and out of the cell and of course they usually end in the alphabets Ace although not all the time most of the time anyway