Transcript for:
Enzymes and Nucleic Acids Overview

we're going to do is focus on enzymes now but before I get into that I need to talk about the different types of chemical reactions that take place in terms of energy exchange when a reaction happens okay so there are two types of chemical reactions with regard to energy exchanges those are the first type is called an exogenic reaction exergonic reaction X means out or literally means reverse energy okay so in an exergonic reaction when a chemical reaction takes place energy in some form gets really okay so we have energy being released therefore after the reaction takes place the chemical products in the chemical bonds that pick up the uh the molecule there's less energy than there was in the reacting molecules because energy has been released everybody understand that you have a certain amount of energy in the chemical bonds and reacting models okay molecules that are acting together and then boom they either come together or they come apart or one comes apart okay and anyways now I've got the products of that reaction and those chemical bonds there's now less energy because energy has been released during the reaction Everybody follow that so that's an exergotic reaction another type is called endergonic reaction I guess an endergonic reaction energy is gained during the reaction reacting process so energy gets absorbed okay so it means then the products in their chemical bonds that make up those molecules are going to have more energy than the reactive molecules had in their chemicals understand that so we can depict that like this you don't need to draw this don't worry about that just to show you on the left is an exergonic reaction so here we have the amount of energy up here in the green molecules okay the reaction happens here are the products now and the products have less energy okay that makes up so we've gone downhill in terms of energy there on the other hand on the right hand side you see an advocatic reaction so here you have the amount of energy and the reacting molecules and then the reaction takes place and now we're up here in terms of the amount of energy in the chemical bonds okay everybody clear on the concept all right so let's look at some examples here hand warmers have you ever see these right okay so with the hand warmers you you cross your squeeze it and then you crush it and it starts to warm up why is that why does it feel warm to you why does it feel warm because teeth are released right heat is a form of energy so so that's an exergonic reaction right the the chemicals that are reacting inside that that pouch there all right releasing energy in the form of heat energy okay so that's an example of an exergonic reaction okay what we call Fire is what what's going on out of this match what kind of chemical reaction it's extra got it right energy is being released in what form forms what is fire It's a combination of yep light and heat exactly right so we have two forms of energy there right light energy and heat energy okay so that's extraordinary okay here's another example the coat pack we're just gonna use the cold pack so this time it's going to feel cold right as the reaction takes place and it's colder because why heat is being absorbed so energy is being absorbed endergonic reaction okay everybody follow all right so we didn't so in chemical reactions we have either exergonic reactions or endergonic reactions taking place okay so All chemical reactions whether they're endergotic or exergonic okay they're not just happening spontaneously they need this kick start to get them going okay so that that's an input of energy to start the reaction going even if it's an exergonic reaction where energy is being released you're going to end up that you know down at the bottom of the hill in terms of energy even that needs a Kickstart needs an energy input and that energy input is called activation energy activation energy so activation energy is the amount of energy that a reaction needs to start like when you start your car okay you turn the key if you have that kind of darn the key and that starts the engine so that that's the energy input to get it started to get it going okay so that corresponds to activation energy and what that does what that input of energy is is it is it destabilizes or loosens up chemical bonds between atoms in the molecules that are going to react so if you're gonna form if the atoms are going to form new bonds you have to lose the old bonds break those old bonds okay so that's what this activation energy does loosens up those old bonds so that so that it's more likely for us to form neutral configurations and then you get the product of the reaction does that make sense okay so the reaction will take place faster you know you can lower the energy requirement to start okay and that is called catalyzing the reaction catalysis or catalyzing reaction refers to reducing the amount of energy that needs to be put in to start the reaction okay so it's kind of it's like a discount so the activation energy is discounted here you need you need less energy to start the reaction so that'll make it easier then for the reaction to get going this makes sense Everybody follow this no um think of it like this got a lawnmower okay now we got two types of lawnmowers before you turn the key or the type where you pull it to start right which one's easier just turning the keys a lot easier than doing this if you've ever done this it's a lot easier okay so that would be catalyzing that particular reaction we can call it that okay so you if there's less energy required to get it going to get it started get the engine started does that make sense okay that's what I'm saying okay so that's called catalyzing that reaction just making it easier for it to happen and if it's easier to happen it's more likely that right so with that in mind now let's talk about enzymes so most enzymes are proteins there are some enzymes that are not proteins so what we're talking about here they're all proteins and they're called globular proteins can you guess what popular it's like all coiled up in a three-dimensional shape okay instead of being a straight chain so like the proteins in your hair those are straight chain proteins okay these are globular proteins all coiled up in three dimensions okay so these globular proteins um then beat up chemical reactions okay or catalyzed chemical reactions so they're doing that in biological organisms called biological catalysts and we need these enzymes to do this because without them we wouldn't be able to survive right so for example in our we'll talk about once we get done with all this chemistry stuff we'll talk about the digestive system and you'll see we produce a lot of enzymes in our GI tract to be a break from the foods as they pass through there okay it would happen anyway without the enzymes but you wouldn't be able to get anything out of the food okay which is way too slow okay all right so we need the enzymes then to speed up these reactions to sustain life now how do they do that well the way enzymes speed up these chemical reactions is number one they increase the chance that molecules will come together I said the increase of frequency of collisions between molecules so if you're going to have two molecules reacting they're not going to react if they don't come together does that make sense so therefore enzymes one-way enzymes speed up these reactions is by increasing the likelihood that they do come together all right that's number one second way they do that is by lowering the activation energy okay and again that's the amount of energy needed to start the chemical reaction so enzymes lower that requirement and then thirdly enzymes properly Orient three-dimensional space the molecules that are reacting so they're more likely to react we need higher seats in the back foreign okay that makes sense all right so that's the three ways that enzymes are speeding up these reactions Orient means turn it around so they're facing each other the right way okay all right now what makes up enzymes it's called the apoenzyme part okay so they have the APO M and I'll Define what these are the apoenzyme and we can have this other thing called either a cofactor or coenzyme okay so those are the two basic parts to an enzyme that the April enzyme and then either a cofactor or coenzyme they put those together and you have What's called the hollow enzyme Polo enzyme okay so the apoenzyme bonded to either a cofactor or a coenzyme now you have the complete functional enzyme which is called the hollow enzyme the apoenzyme is the actual protein structure remember proteins are made by stringing together one amino acids right so this is the chain of amino acids here that's the apoenzyme the term cofactor refers to something that an end needs to function correctly but notice it's inorganic what does that mean again inorganic doesn't contain carbon and hydrogen right okay so if it's inorganic it's just called and a lot of cofactors are the things that you'll find in in vitamin bottles the minerals that are in there those are used as cofactors for enzymes in our in our bodies okay if it's organic it's called the coenzyme so that's the difference between the term cofactor and coenza coenzymes are organic carbon and honey compounds okay later in the semester when we get into how we actually get energy out of food we'll talk about some specific coenzymes okay everybody follow that so far so you take the the protein part here the apoenzyme and then that is combined with either a cofactor or coenzyme and now you have the complete functional enzyme that's called the hollow enzyme a quick all right so let's look at some characteristics of enzymes okay first of all an enzyme speeds up a chemical reaction in living cells okay and that's all it does it just speeds up the reaction and then lets go to the products and then the enzyme can go back and do the same thing all over again so the enzyme itself is not changed by that reaction okay all it's doing is it's speeding up that reaction enzymes are very specific for what they do so enzymes are not good generalists they're specialists okay so as you'll see when we get into the digestive system we have a lot of different enzymes that we produce to be able to break down our food completely so lots and lots of different enzymes because every one of those is specific for a particular reaction okay um third characteristic is the enzymes can at least potentially depends on what the environmental conditions are so uh for example let's say let's see all right so I've got two markers here two markers here so these are the reacting molecules so if I'm an enzyme and I put these together then I have this as the product let's call this a Dye marker okay all right and then I can go back and do the same thing all over again you know take another two markers join them together and then I've got the product right or I can I can this and separate it into the two individual markers okay it just depends on which one I have more of okay if there if there are a lot more of these then the reaction is more likely to go in the direction of taking them apart Everybody follow okay so that's what I mean by catalyzing in both directions I've already mentioned that enzymes will lower the activation energy again that's the energy requirement to start the chemical reaction so enzymes lower that another characteristic of enzymes is you change speed into the reaction that could not happen anyway so the reaction itself has to be possible or an enzyme to be able to help so again enzymes do not speed up reactions that would not happen without them it's just that they speed the reactions up so they're happening you know maybe hundreds of times faster than they would otherwise does that make sense all right catalyze means speed up the reaction yep okay so let's take a look at the method of actuality how enzymes do this oh okay so again an enzyme is a protein and it may have this cofactor or coenzyme attached to it but the protein part again that's globular so it's just coiled up three-dimensional shape and because of that particular shape there's an area on the enzyme called the active site okay so there's this area on the enzyme called the active site and it's called that because that's where the action happens kind of the active site so the molecule or molecule that are going to react think of the markers here again for example okay these are called the substrates okay so the substrates bind to the active site so think of my hands as the active site okay so the markers attach themselves in there because they they fit just right and then the reaction happens and the enzyme releases the product okay if it's going the other way then this would be called the substrate okay does that make sense depends on which way you're going you call the substrate so if I'm joining these two markers together these are the substrates okay and then this is the product if I'm taking this apart this is the substrate and these are the products everybody understand the terminology there yep the substrate is whatever attaches to the active site so this is these are the substrates if I'm going this way to put them together okay if I'm taking it apart this is called the substrate so they in in either case they fit just right or they can be made to fit just right we'll talk about a minute here okay is that clear did that answer all right so how does that happen well two different two different uh explanations for how this happens one is called the lock and key hypothesis or lock and key mechanism and that is just what it sounds like okay we got a lot they got a key to Keep Us Alive okay so the substrate fits into the active side of the enzyme just like a key fits into a lot does that make sense all right so that's called the lock and key mechanism or lock and key hypothesis and that explains some and some reaction others are explained by What's called the induced fit hypothesis or mechanism okay so what does that mean that means you have you have those substrate that doesn't quite fit doesn't quite get into the active site but when the substrate gets close to the enzyme both of them change shape a little bit so now they fit that's called induced fit okay everybody understand the difference between these two so in this case the substrate fits just right into the active site in this case it doesn't but it's induced to fit as the molecules get close to each other there's an interaction between okay so here's an example of lock and key right the yellow thing is the substrate okay the reactant that's a substrate here's the actor right here okay and again all these circles here are what represent what is enzyme made of amino acids these are all amino acids here okay and because of the specific amino acids that are used to make this that's why it has this shape okay because of interactions between the amino acids so that if you remember that's called the tertiary structure remember that term tertiary structure so this tertiary structure you see up here um because of that structure we have this area here this this slot here okay that has just the right shape where this reacting molecule over here can just sit in there okay so this would be the substrate right okay the substrate is going to sit into the active site okay then the reaction happens so this is taken apart for example and then the products are released and then the same enzyme here can you go back and do the same thing again with another substrate molecule that answer yeah okay all right so this figure shows you again what I'm talking about so here's the enzyme the purple thing over here okay and there you can see um two substrates in this case right the blue one the red one here's the active site okay so because of this particular shape this model that has just the right shape to fit in over here this molecule is just the right shape to fit in over there all right everybody follow so they both sit in there and just for a brief fraction of a second we have this thing here this is called the enzyme substrate complex and it just lasts for just a fraction of a second okay and then we have the reaction here and then over here the yellow magnet that's the product okay so that product gets released and notice the enzyme is exactly the same thing as we had over here on the left all right everybody follow that okay so that's that's okay now enzymes uh the word nomenclature means how do you how do you name things that's called the nomenclature so for enzymes many enzymes are named by this scheme there are exceptions okay but many enzymes are named based on taking the root of the substrate name and and the ending a-s-e okay again not universally true but a lot of enzymes are made this way let me just show you a couple examples maltose remember that's a disaccharide Right double sugar disaccharide that's grain sugar so when you eat like cereal for example it contains maltose what's going to happen is that passes down through your GI tract because you're going to produce an enzyme in the small intestine which is called maltase okay notice we've taken the root of the name Malt House and added the ASE ending so what breaks down maltose is Maltese okay and remember that's digested into the two monosaccharides two glucose molecules okay see the scheme the naming scheme there is another example lactose milk sugar all right so when you drink milk or dairy products containing lactose in the small intestine again this enzyme called lactase okay um the lactase then breaks the chemical bonds and lactose to release the two monosaccharides glucose and galactin do this because you can't get anything directly out of lactose or malts they're too big to get absorbed so you have to break them down okay now sometimes people don't produce enough lactase or at all and so they can't break down the lactose so what would you refer to those people as well right lactose intolerant right because the lactose just passes right on through except instead of being broken down okay is that clear so there's the general naming scheme for friends and when we when we get into the digestive system like I said you'll see a lot of different enzymes and many of them are named that one okay Okay so we've got enzymes eating up chemical reactions so those reactions happen fast enough to Keep Us Alive there are five basic factors that affect how fast that reaction happens okay five major factors the first is for sure the temperature of the surroundings the environment where the reaction is taking place so take a look at this graph here we have temperature on the x-axis here degrees Celsius so we're going up to the up increasing temperature going to the right and then the rate of the reaction is shown on the y-axis here so the higher you go the faster the reaction what would you say is the optimal temperature for a human enzyme approximately to look like what is it it's right around 40 right you see that okay human body temperature is 37. 37 degrees is normal human body temperature on the Celsius scale okay so it makes sense that the optimal temperature for enzymes in our body bodies are around that temperature right around 40 37 somewhere in there okay does that make sense over here look at this one this is a optimal temperature for an enzyme from a bacterium that lives in Hot Springs and like old faith so bacteria that live there they have an optimal temperature of what about all right that's pretty warm okay 70 degrees that's pretty warm boiling temperature of water is 100 so that's pretty important so notice that as you go below the optimal temperature the reaction right here for example very very soft right where it increases as you get warmer and warmer right you see that same thing over there why is that because your increased temperature why does the reaction happen faster if you're ready say it again one more time yeah see what's happening here is we've got these molecules all right that are reacting together well they're not going to react unless they come together if they increase the speed of their movement they're more likely to come together in the active site right so by increasing temperature what you're doing is making a molecule move around faster right so notice that's true going they're getting faster and faster and faster until notice the optimal temperature and then what happens Suddenly It's slows way down or stops can you explain why that is why doesn't it just keep going faster and faster enzymes are what kind of molecules what are enzymes proteins okay so what can happen to a protein remember I talked about last week if you heat it up too fast too much denatures remember that falls apart that's what's happening here okay so the protein is getting denatured here so now you don't have that active site anymore because it's falling apart does that make sense same thing over there okay all right so uh temperature as you see here is one factor that affects the speed event reactions everybody clear on that okay the second factor is pH remember pH measures what acidity right degree of acidity all right so here's a similar graph right here notice we have two different enzymes here neither one of them corresponds to the nomenclature scheme that I mentioned okay so passion and trypsin those are both enzymes again in our small intestine or in our GI tract I should say what's the optimal pH of epson about what right about here right two and a half what about uh around seven somewhere around there ready six and a half right you agree okay these are two enzymes like I said in our in our gut which one of those you think is in the stock all right Epson works best at a low PH two and a half remember that's the lower the number the more acidic the environment right so in your stomach you have a lot of acid so one of the enzymes that we're releasing our stomach is pepsin it's going to work best inside the stomach on the other hand trypsin is released into the small intestine where the pH is near neutral around around seven so this enzyme is going to work best in the small intestine that's where it's released like I said because we'll see pepsin is really simple stuff okay all right both of these are protein digesting enzymes they break up proteins in our food all right so pH is another factor and again same thing here so notice that the pH is below the optimal pH it's a slower reaction if it's above the optimal pH lower reaction okay third factor that affects the speed of the reaction is the concentration of the substrate okay concentration of the substrate so on this graph here you can see the substrate concentration along the x x axis on the bottom there and you can see again the speed the velocity of the reaction on the y-axis so what would you say is the relationship between substrate concentration and speed of the reaction looking at this it was a general conclusion from that is this slow reaction right getting faster and faster at as substrate concentration goes up right everybody agree but then I notice it levels off here and now it's not getting any faster can you explain that so it's not just going to keep going huh somebody say something all right remember how this reaction happens you have the reacting molecules right they fit in the active site and while they're sitting in the active site they have the reaction occurring and then the product is released and that opens up the active site again okay so what's on over here why does it level up like you know how we did look um no no that's not enough do we have just one enzyme molecule we have a lot of enzymes same enzyme right a lot of copies okay so what's going on over here when you get to this point when you're looking at this the speed of the reaction levels off it's not getting any faster what's going on there yep yeah because you only have so many enzymes right so at this point it's saturated all the spots all the spots are taken okay all the spot all the seats are taken okay you got somebody gets up you gotta wait till somebody leaves the active site of an enzyme does that make sense so it's saturated no it's going to level off there because you only have so many enzyme molecules so many spots available okay so we you reach the capacity here in other words okay everybody follow that all right another factor that affects the speed of the reaction is the presence of any what are called inhibitor molecules inhibitors what do you think an inhibitor will do to the reaction rate it's based on the name it'll slow it down it'll inhibit it okay all right we're gonna I'm gonna take a little closer look at that in a minute and the fifth Factor is what are called the thermodynamic characteristics the thermodynamics of the reaction energy change or literally heat changes what that means heat changes or energy changes all right so I'm going to look at these two a little more closely here all right you ready for that okay let's look at Inhibitors here all right sure um are going to slow down the reaction but there are two possible types possible ways that can happen so first What's called the competitive inhibitor a competitive inhibitor so what a competitive inhibitor is is a molecule that looks like the enzyme it's got you know a shape that's very similar to the excuse me not the enzyme the substrate so it's got a shape that's very similar to the substrate take a look at the tree so here's the enzyme in purple okay here's the normal substrate the red thing there see the shape of the active site right so that that fits in there right however we've got these this blue thing here that's sitting in the spot so while that's sitting there this can't get it does that make sense so competitive Inhibitors are called that because they compete they compete with the substrate to get into the active site so they compete with the substrate for the active site so that means while the competitor is sitting there again that's the blue thing there while that's sitting there nothing's happened that enzyme is not catalyzing Everybody follow all right so that's called a competitive inhibitor okay uh competitive Inhibitors can be overcome if you provide more substrate because then the odds are better that the substrate will get in it instead of the competitive the inhibitor you understand that anybody have questions about that okay so that's competitive inhibition the other type of inhibition is called non-competitive not competitive okay and here's how this is different so this time we don't have any competition going on this time as you see here again here's the enzyme here's the active sight reader okay here's the substrate notice what happened in this picture is this yellow molecule here has attached itself to the enzyme not in here but somewhere else and when it does that that causes a change in shape of the protein here so the active site doesn't have the right shape anymore follow that so this molecule here is a non-competitive inhibitor it slowed down the reaction or maybe even stopped it without sitting in the active site okay so oops sorry so it binds to the enzyme outside the active site look at this in this picture it's over here right everybody will understand that so it's going to change the shape of the active site here so that it doesn't just doesn't fit anymore okay so an example of the previous one competitive inhibition some antibiotics work that way that's how so many antibiotics kill bacteria they function as competitive inhibitors for essential enzymes in the bacteria so they kill the bacteria cyanide cyanide is a poison and cyanide does is it functions like you see here as a non-competitive inhibitor for enzymes that are very important in our cells that allow us to get energy out of nutrients so if this happens then that enzyme is not going to work and if that enzyme doesn't work you're not going to be able to add energy out of it nutrients and the cell is going to die the person is going to die all right so you understand inhibition in either case it's going to slow the reaction down right or maybe even even stop it but how does that can either be competitive or non-competitive clear all right the fifth Factor um well here let me go through this first so the lay cells regulate uh the activity of enzymes and the reason I'm saying this is making enzymes takes energy it takes energy to make an enzyme for itself to make an enzyme well for example if you don't have any maltose around there's no sense making Mall takes right could you just wasting energy making the Yen sign Paul taste so and cells regulate the production of enzymes so here's what happens what are called signaling molecules are produced by cells in our body and these signaling molecules will attach themselves to enzymes okay and that changes the shape of the enzyme now where they attach is whatever similar to what I just showed you there non-competitive inhibition so they're attaching themselves to the enzyme not in the active site but somewhere else and that somewhere else is called an allosteric site other side so it's not in the active side it's somewhere else on the molecule Everybody follow that so just like the non-competitive inhibition I just showed you but but this is happening in order to control the activity of the enzyme with me here some of you are yep what did you say ouch literally other sites others so it's not in the active site it's somewhere else so the signaling molecules are two types one is called a repressor okay so a repressor is an example of a signal molecule and what that does is it inhibits the enzyme it represses the activity enzyme it slows it down okay the other type is called an activator so these are two different types of signal molecules here some are repressors some are activators activators as the name implies is going to activate the enzyme turn it on okay whereas repressors they're going to turn the enzyme off does that make sense so it's kind of like a switch so if you release a repressor it's going to turn the enzyme off at least an activator is going to turn the enzyme on and now the enzyme can catalyze a reaction Everybody follow us okay okay so here you see an example of both of these let's look on the top first everybody see this yeah okay so here's the enzyme in purple here's the substrate okay that pill-like thing so notice that fits right in here right okay and then you get the product so there's the there's the chemical reaction right there over here 's a repressor that's been produced by the cell or just uh it comes across a repressor might be you know a chemical in food or something and so the repressor fits in here that's not the active site that's an allosterous thing okay so notice when that happens the shape here changes right see that so so this can't fit in there anymore okay so after that's an example of depression the enzyme has been repressed okay on the bottom here notice initially something to get in there so it gets turned away here's an activator molecule okay this fits into this active or excuse me allosteric site that changes the shape of this so now this has the right shape and now the substrate can sit in there now that the reaction happens so that enzyme on the bottom has been activated everybody clear on the difference between these two okay so that's entire repression on the top activation on the bottom okay all right going back to what I said before about not producing enzymes when you don't need them all right here's how that happens this is called feedback inhibition feedback inhibition all right so go ahead and go ahead and draw this out so yeah molecule a molecule B molecule C molecule d all right so enzyme one converts molecule a to molecule B okay so that's one reaction now you have molecule B enzyme two converts molecule B to molecule C thanks and I got C enzyme 3 converts molecules C to molecule d okay so we have three different reactions here right and series one reaction leads to the next which leads to the next okay everybody understand that so we've got we started out with this molecule here and that's going to be used eventually to make that molecule there deeper right but it happens not just one by one reaction happens through a series of reactions okay all right so now molecule when molecule D shows up and it starts to accumulate molecule d acts as a repressor for enzyme one here okay so now this enzyme is repressed therefore you don't get any more d because you don't have a being converted to B you understand this so in other words this is a way to keep the cell from making too much of uh of this molecule over here okay so you're not wasting energy making more than what you need and so there are lots of different intertwining chemical reactions that happen in the cells in our cells and a lot of them work this way that's called feedback inhibition because this feeds back over here inhibiting the production of any more of d okay questions about that so here we have inhibition in a good way okay because you don't want to accumulate too much of a product you don't want to make too much of a particular amino acid if you don't need it yeah so inhibition is inhibition in general just means slowing down yep so in this case we're slowing down this reaction too much of that okay so is this to show up you got more and more of these molecules around right some of them will attach themselves to this enzyme which then stops this reaction so therefore you don't accumulate too much of that makes sense yeah everybody good all right okay so again um these enzyme catalyzed reactions are the rate of those reactions it's in by what so far what influences the rate of the reaction temperature number one what else pH okay what else but well temperature right temperature pH substrate concentration presence or absence of Inhibitors right and then fifth the thermodynamics so let's talk about that now okay all right so how thermodynamics affects the reaction so first of all thermodynamics that word Thermo Thermo refers to heat thermometer right thermostat so that's heat dynamic means change literally heat changes okay in other words energy changes what a reaction happens okay so let's say we have these two reacting molecules it could be the the markers here again right so the two markers I have all right maybe Everybody follow okay molecule a molecule B okay so they come together you get the product C is that clear a plus b produces C and this is catalyzed by an enzyme okay notice the double arrow that tells you that it could potentially go either that way or this way right okay if there's more A and B A and B are represented by the separate markers here okay so if we have more of those then the odds are that the reaction is going to go that way to produce C right just because there are more of the individual markers than there are of the double margin right okay so if we have more AP it's going to push the reaction to the right the way you say that the reaction to the right it's more likely to go that way okay if we have more C on the other hand it's going to force the reaction to the left okay is everybody clear on that concept yeah about to get lost so you're with me there so far okay now yeah this reaction is an exergonic reaction what does that mean excellent energy releasing right okay so if we're going to believe if we're releasing energy where do you put energy on this side or this side is energy a product or a reactant on this side okay so how many Vote for This sec all right how many vote for this side how many don't know okay energy releasing right so you can think of energy as a product right so therefore energies go up on this side you understand that it's exergonic it releases energy just like this releases this product right okay that's an exergonic reaction all right give you another chance here all right so if we think of this reaction going to the right okay if it comes back to the left then we think of that as slowing down you understand okay so if we have a lot of energy that's going to push the reaction back this way right just like if we have a lot of C it's going to push it back this way forever all right on the other hand okay here's your second chance so if we have an endergonic reaction where do we put energy yep okay so energy now goes on the left side right you can think of it as a reacting molecule in the same way so 100 goes on this side okay so now if we have energy over here just like if we have a lot of A and B we have energy over here a lot of energy because anyone has gone back to a that's going back this way this this reaction can go either way right so in other words with the markers here I can either take the separate ones and put them together produce the product or you can take the product and break it up into these right that's what that that's what this means so if I have a lot of these individual separate markers then it's more likely to go to produce this as the product the double market right on the other hand if I have a lot of these then it's more likely to go the other way right okay now think of energy in the same way so if I have a lot of energy that's an if if I have an X organic reaction that means energy is on this side so if I have a lot of energy it's going to push the reaction that way okay on the other hand here energy is on the left side correct so now which way is that reaction more likely to go to the right or to the left okay so energy is going to speed up that reaction okay do you understand that so what kind of chemical reaction that is also affects the speed of the reaction whether it's exergonic or endergondic okay any questions about that everybody good with that all right okay so now we're going to do a switch to the fourth group of macromolecules that we're talking about and again just to summarize what we've done so far talked about the structure of carbohydrates lipids proteins which include enzymes and now we're going to talk about nucleic acids okay so again these those four are called the macromolecules or biologically important molecules because they're found in every living cell all right unlike some of the group you went through in that handout the alcohols and so forth the hydrocarbons okay so organic also but those don't make up much of you know living cells okay whereas these four do okay and therefore they make up the majority of our food too where their food comes from living things so nucleic acids are the fourth group here two types of nucleic acids and those are DNA and all right DNA and RNA so these are the two types of nucleic acids let's learn a little more about them right so if you didn't know this before you will now um DNA everybody happens okay DNA stands for deoxyrino nucleic acid the D or the N or the a okay deoxyribonucleic acid so again if you didn't know this before you're about to learn where that name comes from all right deoxyribonucleic acid DNA so this is a chemical DNA and RNA are chemicals DNA everybody's heard of DNA um DNA is what performs our genetic code okay and after we go through this we're going to talk about what that means exactly genetic code okay so it forms a genetic code and the reason these are both called nucleic acids is because DNA was the first one discovered and it was isolated from the nucleus of the cell okay DNA is also found in mitochondria we're focusing on the nuclear DNA here so DNA is in the nucleus of the cell and again it forms a genetic code okay everybody have that so that's DNA okay deoxyribonucleic acid RNA the other type of nucleic acid and it stands for rival nucleic acid so the only difference in name here is we're missing the DIC okay so R ribonucleic acid okay the role RNA plays in the cell is it takes the genetic code which is in which is in the DNA and it uses that information denied the production of proteins in the cell remember proteins are made at the what the ribosome right okay so the RNA is used to guide the production of proteins and ribosomes using the information that's in DNA which is in the nucleus okay so in order to make that happen there are three types of RNA they each have their own role to play in this process these three types are called ribosomal RNA or little r RNA messenger RNA RNA and transfer RNA in order for a cell to be able to make proteins based on the information in the genetic code in DNA okay so far go back yeah okay so ribosomal RNA so after you see a ribosome here's a ribosome right here okay glycosomal RNA a little r r all that because it makes up the structure of ribosome so the ribosomes in other words are made of proteins and ribosomal RNA complex together that's what makes up the structure of a ribosome like you see here okay so ribosomal RNA is used by the cell to make ribosomes I clear so here's a ribosome made of ribosomal RNA and protein messenger RNA is called that because messenger RNA carries the message from d on it again the genetic code is in the DNA as we'll see that code gets copied into messenger RNA and that's what you see right here this brand that you see right here that represents messenger RNA so the the genetic code has been copied into messenger RNA what's going on in this picture is this ribosome is reading message okay so this the signal the message is carried from the nucleus where the DNA is located out to a ribosome ribosome and the cephalasm by messenger RNA clear and then the third type of RNA Transfer RNA is called that because you see over here for example Transfer RNA molecule and what it's doing is it's transferring an amino acid to the right Zone so the amino acids can be bonded together to make the protein okay this makes sense everybody and then in order to get that genetic code another in other words compared to use that to make a protein we need all three of these types of RNA to complete that process Everybody follow okay all right so before we get into that let's take a look at the structure of both DNA and RNA so nucleic acids again either DNA or RNA are big molecules okay and just like proteins are made from amino acids nucleic acids are made from molecules called nucleotides okay so the nucleotides are the building blocks the legs that are joined together to make a nucleic acid either DNA or RNA right everybody understand that concept so far so we take these smaller molecules together to make DNA or okay so here you see a picture of a nucleotide right here okay so every nucleotide has three components three components so every nucleus High contains What's called the nitrogenous base okay and that's represented over here in the peach color all right so there's the nitrogenous base can you guess why it's called nitrogenous yeah a lot of nitrogen atoms correcting them all so that's called the nitrogenous base secondly we have a pencils remember what that means so here you see the five carbons one two three four five same number there that's a five carbon sugar that's called a pentose all right so we've got the nitrogenous base over here in the peach color and that's bonded notice okay and then those two together that's called the nucleoside and then we add the third component here which is called the phosphate group that's the one of the functional groups I referred to before okay phosphorus in the center surrounded by all the oxygen there okay so when that's bonded to the sugar okay so nuclear side it's just these two when you add this in that's a nucleotide Everybody follow so that is a building block right there the nucleotide okay the nitrogenous base nitrogenous based um in DNA consists of one one of four possibilities all right so we've got four different nitrogenous bases those are either atomine or guanine adenine of guanine okay you do not need to know these structures don't worry about that they're showing you the pictures so you can see what the molecules are here's the adenine here's one okay they're usually just abbreviated A and G A and G okay now these are called purines these two are called purines okay notice what they have in common is they both have two rings see that double ring structure so the purines have a double ring structure okay when we get to the structure of DNA all right so a nitrogenous base can either be adenine or guiding or cytosine or thiamine your cytosine here's thymine okay so in DNA we have one of these four right here and again these are just usually if you get a c and T all right these two are called pyrimidines so cytosine and thymine are called pyrimidines notice how they're different from the purines they only have one ring all right everybody see that it's a single ring these have a double ring these have a single ring so we're going to have one of those for okay and they're usually disagree just use the first letter so a g c or t clear all right in RNA RNA we also have four possibilities that's where I stopped last time yeah so in RNA again four possibilities two of those are the same purines adenine or guanine okay a or G so that that's the same the other two possibilities are again perimetings okay the difference is instead of thymine what you see in the bottom here instead of having thyme DNA excuse me RNA does not contain thiamine instead of containing uracil in its place and that's shown over here on the right hand side and the bottom okay so in RNA the four possible nitrogenous bases are a g c or U that clear that's one difference between DNA and RN DNA contains thymine not uracil RNA contains uracil not thymine a little bit better on that all right so again that's the nitrogenous bit and as we'll see that becomes the basis for What's called the genetic code okay which specific sequence of nitrogenous bases is found along DNA all right the sugar is also different between DNA and RNA so again here's a nucleotide okay so there's the nitrogen space we just talked about over there in DNA that's going to be either a g c or t right an RNA that's either a g c or U okay all right here's the sugar the pentose down here and notice that the sugar is numbered the carbons in the sugar are numbered starting over here okay this will become significant a little bit this is called The One Prime carbon two prime carbon three prime carbon four Prime and five Prime carbon right there okay so they number they numbered that way clockwise you'll understand why I'm imagining that a little bit all right so the pentose again that's the sugar so that's this right in DNA that sugar is called deoxyribose and that's where the name comes from deoxyribonucleic acid okay so that's the sugar here that's found in DNA in RNA the sugar is ribose so there's a second difference between DNA and RNA DNA contains deoxyribose RNA containers ribose see those names are similar there all right we take a look at the actual sugar here let me zoom in on it okay you can see the difference is where it says R right here okay so in RNA that's an o h hydroxy remember it's called the hydroxyl group okay that's what you have over there an RNA and DNA is just hydrogen so that's the difference okay D that's why it's called deoxy missing the oxygen okay everybody understand so there's a second difference between d i and our next first difference is in DNA thymine instead of uracil and RNA uracil instead of thymine okay the second difference is the sugar is different okay all right so again every nucleotide again this is a nucleotide these are the building blocks that are bonded together to make either DNA or RNA um so every nucleotide has a nitrogenous base bonded to a pentose sugar and then that in turn is bonded to the phosphate group so there's a nucleotide put on that so far all right so to make both DNA and RNA these nucleotides get strung together in these long chains what happens is the pentose the sugar of one nucleotide forms a bond with the phosphate of another one that repeats itself over and over and over and over again so we get What's called the pentose phosphate backbone to the molecule that's true again for both DNA and RNA okay so we can picture that like this so here's one nucleotide here's the nitrogenous base here's the pentose sugar here's the phosphate group there's another nucleotide right here here's the nitrogenous base contose sugar phosphate all right everybody follow okay oops sorry so then what happens is we get a bond here between the phosphate of one nucleotide the pentose sugar of another that's called the phosphodiester bond right there so phosphodiester bonds are what join nucleotide together those are called phosphodiester bonds so similar to what happens to form proteins from amino acids right remember amino acids are joined by peptide bonds these are called phosphodiester bonds Okay so we've got these long chains of of uh nucleotides and again this is true for both DNA and RNA all right now when this happens in the cell it always happens starting at one end and going towards the other end of the molecule the chain here okay one end of the chain is always called the five Prime end and the other chain okay and this is always catalyzed by an enzyme like I said and we need enzymes to do everything your body okay so there's an enzyme that joins this to that these two sit in the active site of the enzyme and the enzyme bonds them together to form the phosphodiester bond okay the enzymes remember are specific so the enzyme that does this always starts at this end and goes that way it never starts at this end it goes this way it can't do this okay and this is true for all living things as far as we know okay so always starting at the five Prime end and working in the three prime Direction all right so let's see exactly what I mean by that don't try to draw this okay all right here we have a nucleotide and a nucleotide right okay but you understand so two nucleotides all right Watch What Happens here Okay so notice there's a hydroxyl group here oh on the sugar okay so that comes off and notice over here there's a hydrogen on the phosphate okay so that comes off we get one what's that called again when we pull water out yep dehydration dehydration right so that's a dehydration reaction when the water gets pulled out we got this new bond between the two nucleotides that's the phosphodiester bond is that clear so that process repeats itself over and over and over and over again okay so you end up with this long chain of nucleotides joined together by phosphodiester bonds when it's all said and done then if you look up the top end of this of this structure here remember I said to pay attention to the numbering and the sugar okay so this is always something one prime carbon and it goes clockwise this is the five Prime carbon okay at one end of the molecule we still have um Let's see we still have the phosphate bonded to the five Prime carbon okay all the way at the other end we still have o h on the three prime with me there everywhere in between we pulled the water out so the o h is how to make water right anybody follow that so this end up here where we have the phosphate Bond into the carbon that's called the five Prime end the other end where we still have the hydroxyl group The oh that's called the three prime end okay all right so we can depict that here here's the five Prime end up here there's the three prime end down there of the of the chain everybody understand all right so it always goes that way like I said the enzyme that joins these nucleotides together always works going that way starting at the five Prime end and going at a three prime Direction is that clear it never starts at this end and goes that way okay all right so we have the the fox the pentose phosphate backbone here then we have these nitrogenations here and those notice are attached at this at this point here which is the one prime carbon okay so the nitrogenous bases are sticking out from this chain as you see here and they are bonded to the one prime carbon of the sugar okay again that's true for both DNA and RNA I have any questions so far a couple significant things you should remember nucleotides are always added starting at the five Prime ad and working in the three prime Direction okay to form this backbone of the molecule we have we have a pentose or a five carbon sugar a one nucleotide over here one nucleotide bonding to the phosphate of another and again that repeats itself over and over so we've got to sugar phosphate sugar phosphate Etc that's the balance and then sticking out from there bonded to the one prime carbon of the sugar are these nitrogenous bases which again could be adenine for example cytosine you know flying Etc Everybody follow them all right so the form DNA then or DNA we have two of those strands that I just talked about two of those chains that are twisted around each other as you see a picture here and this is what's called the double helix structure the language structure this was figured out by Watson and Crick in the 1950s figured out this structure one of Nobel Prize for that so we've got the two strands as you see there twisted it around each other like a ladder that's twisted okay so that's what's called the double helix okay the two strands are complementary to one another okay they're complementary what that means is whenever there's an adenine in one strand there's always a thymine in the other and those are held together by two hydrogen bonds remember what hydrogen bonds are okay so you've got a hydrogen it's part of one polar covalent bond and another as part of another polar covalent bond and so there's an attraction between them that's the hydrogen bond okay so there are two hydrogen bonds that join those together and then whenever there's a guanine in one strand there's always a cytosine in the other those are held together by three hydrogen bonds so that's what complement complementarity that's what it means to say they are complementary to each other so take a look over here so here you see for example here's cytosine okay in this strand therefore we have guanine on this strand and they're one two three hydrogen bonds holding those together up here is thymine in this strand on the left therefore adenine and the Strand on the right held together by two hydrogen bonds understand that okay now remember I said that pure rates are adenine of one right adenine and line and they have the double rings okay the pyrimidines are cytosine and thymine and Di uracil and RNA those have one ring those are the perimetings notice we have a DOT over here a single ring over here here we have a double ring over here a single ring over here what that means is the distance between these two is always the same to follow that okay all right so again they are out the two strands are complementary so if you're given the sequence in one strand you can figure out the sequence in the other also the two strands are anti-parallel they're called anti-herald all right so what's that the word anti-federal okay so they're complementary and they're anti-parallel okay so this is what I have my parallel means this is part of both strings so we've got two nucleotides on the left side two nucleotides on the right side all right and here you can see the hydrogen bonds that are holding the two chains together right three here two there okay you see a difference between the left side and the right side other than the specific uh nitrogenous bases you see anything else different take a look at how the sugar is oriented the blue colored sugar there are excuse me purple colors each other notice on the left side the oxygen is on the top the right side the oxygen is on the bottom all right the reason for that is on this side it's running this way on that side it's running this way okay that's what anti-parallel means so here we're looking at the two strands notice at one end on one strand this is the five Prime and this is the three prime end on the other strand this is the five Prime end and that's the three prime follow that so anti-parallel means they run in opposite directions okay so they're complementary number one we've got C here therefore G there Etc and secondly they're anti-parallel meaning the strands run in opposite directions okay any questions about that good all right so that's DNA here's RNA okay RNA consists of one strand is one string okay so DNA has two strands RNA has one string like the Coronavirus is an RNA virus okay RNA so the nuclear the genetic material in the coronavirus covid-19 virus is RNA okay all right so several differences between DNA and our DNA has two strands we have one strand sugar and DNA is called what what's the name of the sugar found in DNA starts with the D deoxyribose the name of the sugar in our RNA is ribos okay the four nitrogenous bases found in DNA are what a G c or t the four found in RNA are a as you C or U okay DNA is found in the nucleus of the cell and the mitochondria as I mentioned last time RNA there are three types right messenger transfer ribosomal so it depends on the role it plays where it's found in the cell okay all right so several differences again DNA and RNA all right