Exploring Enzymes, Water, and Acids

Oh well today we're going to be covering enzymes, water, acids, and bases. So let's go ahead and hop into our learning outcomes. So today we want to look at the notation and basically how we write and how we describe chemical bond formation and chemical reactions. And then we're going to look at the energetics of those reactions, whether they require energy input or whether they give off energy. Then we're going to look at some of the different factors that determine reaction rates. Okay so how fast Do these reactions occur under different circumstances? Then we're going to look at enzymes, what they do, why they're important. We want to take another quick look at water and look at why it's important as a solvent and look at its polarity. And then we're going to look at acids and bases, specifically the concentration of H-plus ions in the solution as it relates to the pH scale. And then we... to look at a pH buffer system and look at how your body resists changes inside of pH. So starting with our notation and energetics, what we're going to be talking about is the energetics from chemical energy. So all the energy that you use in your body is chemical energy, things we get from breaking down bonds between chemicals. So most of this energy, of course, is acquired from food for us. And all of the chemical reactions that are going on in your body are going to fall into two different categories, right? Based on whether they require energy input or whether they give off energy when the reaction happens. So an endergonic reaction, endergonic reactions are going to require an input of energy, okay? So ender, right, is going to require an input. of energy for the reaction to proceed. A reaction that is exergonic, okay, so exergonic, X here, EX, is going to release energy. The reaction proceeds. Okay, so let's look at this kind of in a graphical way. So here's an example, here's our graph of what happens in an endergonic reaction. So we're going to start out with our reactants, that's the products that were the things that we're beginning with, the molecules that we're beginning with. And then we're going to have to input energy here into our system, right? So you can see that this is going to require an input of energy here. And then we're going to create our products, right? And our products are what we end a chemical reaction with, right? So endergonic here, you can see we're going to require us to put this energy in. So what's a biological example here of an endergonic reaction, right? One that you should be familiar with. Well, photosynthesis here is the classic endergonic reaction. So inside of photosynthesis, our products here, okay, will be here on the left side of our reaction. So we're going to, I'm sorry, I just think I just said that backwards. Let's start this slide over again. So here we have a biological example of a endergonic reaction. and kind of the classic reaction for reaction is photosynthesis. So let's take a look at photosynthesis. So in photosynthesis, we're going to start with our and our reactants here, our CO2 and that are going to be created are going to be on our right side here. So this is going to require an energy input to Change these low energy products, the CO2 and energy product, right? Plants get that massive amount of energy that they have to input into this process from capturing sunlight. So the sun is going, the question here, what plants get. So now let's flip over and look at an exergonic reaction. We're going to see that it's just the opposite, right? So an exergonic reaction. is going to release energy. Okay, so now as we move from our reactants, right, which was on the left side of our equation here, that's what we started with, energy, and this is going to mark it being an exergonic. So let's look at a biological example of an exergonic. Okay, this is what goes on in our bodies for cellular respiration. So now we're going to start with that glucose. Let's assume that you ate. something sugary or carbohydrates and sugar, and you've taken in the glucose. Now we want to break that glucose down so that we can get the energy from it, that energy release from the exergonic reaction. So we're going to start with our reactants. So this time our reactants over here are going to be our glucose and our oxygen. We eat glucose with our food, we breathe in oxygen from the air. And our products is going to be CO2 and water. and then the energy release. So then we're going to exhale that CO2 to get rid of it. We have the water in our system that we can excrete if we need to. And we've harvested now this energy, right, about, tells you there about 686 kilocalories of energy from breaking down this glucose molecule. In all these chemical reactions, I was already using these names, but I didn't exactly define them for you. So I just want to give you... definition here when we're talking about the notation of these reactions. The reactants are what I had on the left side of the equation here, and it's the substances that are entering into the reaction. Sometimes we have some intermediates. I didn't talk about intermediates here, but you might have some intermediate products that are just there temporarily for a short amount of time, and then eventually you'll get into your products, which is your final result, the end result of the reaction. Let's continue this notation and look at a couple of classic chemical reactions. So we're going to have our reactants on the left. We're going to have our products on the right. And we're just going to use some A and Bs here to represent basically any types of chemical compounds here. Just kind of use them as a generic form, kind of like you would in algebra. So a decomposition reaction is when we're going to start with two things, and they're going to... decompose and basically break apart into two individual items. So a decomposition is going to start with an AB and that's going to decompose into A plus B. That is in direct opposition to a synthesis reaction, which is going to be the reverse of that. So that's going to be starting with an A and adding a B and then the product is going to be AB together. These reactions can be reversible. as you see in the bottom right hand corner, and to denote a reversible reaction, we're going to put an arrow going in both directions. If that reaction was not, when we're not doing it, it is not a reversible reaction, we're going to draw a single arrow in the left to right, a direction indicating we're going from our reactants to our products. So if this is reversible, and this equation can kind of slide back and forth based on different factors and concentrations and other things that we're going to look at, Then it's said to be reversible and we denote that with the double arrow going in both directions. Another classic reaction that we're going to see is an exchange reaction and we're going to see that in the bottom left hand corner there and that's starting with an AB plus a CD and then you're going to exchange those and so then you're going to end with something like AC and then BD. Okay so here's a couple of examples of reactions for you. Let's replace our A's and B's now and actually put in a couple of examples here for you. So on top, you're going to see a reversible synthesis and decomposition reaction. So if we take carbon dioxide and make a carboxylic acid out of that, this is how CO2 is transported through your body and bloodstreams can be excreted at the lung. right so it needs to basically take co2 in its gases form convert it to something it can move this carbonic acid moves it through your and then it converted back to co2 for you to exhale an example of an exchange reaction and here you see what happens if you mix we have a hydrochloric acid and sodium hydroxide so we're missing mixing HCl here in a OH and if we have the exchange reaction here we're gonna exchange OH with the H, that's going to give us H2O, and ACL, which is basically salt. Mix an acid and base together, that's what you're going to get. A little salt. We have been talking with a bunch of chemistry so far. Chemistry, intro chemistry is a prerequisite for the course. Kind of focus and move away from just kind of... their chemistry and start to focus on chemistry. And so biochemistry is that combination of biology and chemistry. I mean, so we refer to it as the chemistry of life. So now we're going to start. Putting all of this, the chemistry and the reaction mechanisms that we looked at, in a organic, in a life-based setting. And in that, we're going to find that the chemistry of life involves organic compounds. So an organic compound is a compound that's going to contain carbon that is bonded to hydrogen. So when you go to take organic chemistry, for example, it's all about these carbon-containing compounds. Inorganic then are going to be compounds which do not usually contain lots of carbon, right, bonded to hydrogen. And there's some other examples there, you know, water, acids, bases, salts, right, those are just some examples of inorganic chemicals. I also want to highlight here, since you haven't had organic chemistry yet, that when we draw these different chemical compounds, and you're going to start to see some of those as we get into macromolecules and stuff in the next lecture, that we don't want to draw out the entire chemical structure because it's just way too complicated, way too much information that we don't. So organic chemists have a kind of shorthand version for drawing compounds, and this is the way you're going to see a lot of the compounds presented as we move forward. So just to refresh you on chemistry and make sure that you're not confused about the structures you see. I want you to know and make sure that you understand that these two structures are equivalent to each other, meaning the hydrocarbon chain you're seeing on the left is exactly the line structure that you're seeing on the right. So how have we reduced that? Well, the way we're going to kind of shorthand this is we're not going to draw any carbons. What we're going to say is at the intersection of these lines, we're going to assume there's a carbon. So if we go in and we put our carbon in, Everywhere that there's an intersection on these lines, we'll see that we have our six carbons, okay, the same six carbons that we have right here in the center of the compound. And then we assume that if there's not something properly written there, that that carbon is filled in with hydrogens, okay? So I can now go back and H on each one of these, right? That carbon only had one connection. It wants four. So it needs three hydrogens. This carbon should have two hydrogens on it. So you could go through and fill all those in if you wanted. But instead of having to draw all this and have all these carbons and hydrogens and have all this clutter in the way, it's much easier for us to be able to draw a simple line structure. Exactly. Exactly. So as you start to see these carbon rings and these other structures coming up, all those carbons and all those hydrogens are there. It's definitely still an organic compound. We're just not drawing for simplicity's sake. All right, so now let's kind of shift gears and start talking about what are the factors that influence reaction rates? Okay, so we've got some reactants. They're going to be converted to products, right? How quickly does this happen? A couple things that have to happen in options. The first thing is, electrons have to come in physical contact. They cannot bond with each other if they don't leave each other and come. And the next thing that happens is they must overcome the pulse of force of their electrons. So those valence shell electrons, right, going around the outside, we've got those positive and negative charges, right? So if they don't touch each other in the correct orientation, And if they've both got maybe a positive side and a negative side, and the two negative sides combine and touch each other, they're still going to get repelled. So not only do they have to come in contact, they have to come in contact in the right orientation and be able to overcome this repulsive force, right, of bringing electrons for each other, which is what's going to happen when two atoms are close to each other. So our different factors that are going to influence these reaction rates are down here. And so we want to look at concentration, our reactants. The temperature the reaction is occurring at, okay? Our different reactant properties, right? Solid, liquid, gas, things like that. And then is there a presence of a catalyst? So breaking these down, how does concentration influence a reaction rate? In general, the higher the concentration, collisions you're going to have, so the faster the reaction rate. The concentration, the lesions, the faster reaction length. Low concentration means fewer collisions, means less probability of two things, you know, coming together in the correct orientation. And so that's going to happen at a slower rate. There's a point where, this is all part of negative feedback, right? There is a point where you can increase the concentration so much that it starts to have a negative effect, right? But in general, especially at lower concentrations, increasing the concentration is going to speed up. the reaction. We also need to consider our reactant properties. Okay, so let's talk about something, say, as a solution that's something that is solid. Okay, so reactions that take place inside of a liquid or inside of a solution, right, take place much faster than something in a solid. Why? Once again, it's about number of collisions, right? So things that are molecules that are in a solid, they don't move very far or very fast, right? So their number of collisions is very low, right? So anything that happens in a solid phase is going to have a much slower reaction rate than something that happens in the solution phase. Also, going back one slide here, let's take a quick look at the rusty car in the lower right-hand corner, right? And think about this as well. Where does rust happen? Okay, so rust is a reaction. It's oxidation of metal. And it happens where air, right, is touching that surface. Does rust happen in the middle of a solid piece of metal? No, it doesn't. Because there's not oxygen that is available in the solid piece center of the metal, right? So this reaction can only happen on the solid surface where it comes in contact with air, for example. So that solid phase is going to limit reactions to only happening in the surface because in the interior nothing is available for reaction. We can also talk about temperature. So when you increase temperature, you increase the amount of kinetic energy in the system. So energy is not created or destroyed. It has to go somewhere. So when you add temperature into the system, you're adding energy into the system. And that's going to result in kinetic energy of the molecules. It means they're going to move faster. So if they are moving faster, so a high temperature means that they're moving a lot faster. If they're bouncing around very speedily, chances are that they run into somebody in the correct orientation, goes up the faster the particles. So that means things that are cold and slow, that these particles move slower. And that means that they're going to then have a lower or slower reaction rate in colder temperatures. And then finally, we want to talk about the presence of a catalyst. So we're going to be looking at enzymes coming up, which are our biological catalyst. But inside all of chemistry, you can have a general catalyst. And a catalyst comes in and speeds up the reaction rate. And it does this by lowering the activation energy that's required for the reaction. So remember on our graph when we were talking about an endergonic reaction, right, requires this energy input into it. A catalyst is going to lower that energy input that is required, making this matching process faster and more efficient. So catalysts are going to speed up. The presence of a catalyst is going to speed up this reaction rate. So, like I said, in our bodies, our catalysts are enzymes. So enzymes are proteins that are inside of our body, and they want to lower that activation energy down and make this reaction process more efficient so that it happens faster. So how do they do that? Well, they're this reusable protein, and they are highly specific for a particular reaction. And basically they... play matchmaker in this scenario and they help the reactants find each other in the proper orientation so that they can speed up the reaction and make it much more efficient, right? Which actually requires the energy that's required for it to happen because you're not wasting energy having things just randomly bump around and not run into each other in the correct orientation. So looking at a cat, at a enzyme here as a catalyst, on the right we have an example of an enzyme called sucrose. Sucrase, sorry. So sucrase is the enzyme, and what it does is it takes sucrose, that's the substrate, that's the reactant that we're going to start with, and it actually breaks sucrose in half into glucose and fructose. So normally, this reaction does not want to proceed. Once sucrose is together, it does not want to break apart. So if you want To acquire the glucose, say, that you've been having in your body as sucrose, and you need to break that back apart, having this enzyme available is going to make that a much easier and much more efficient process, and it's also going to speed it up because it is a biological catalyst. So here's the graphical representation, bringing those graphs back of what we were talking about. So we had our energy of our reactants over here. And we're going to go through a process, and this is the energy of our products. Okay? So what we're doing here is this is actually an exergonic reaction. Right? We need to get a release of energy, ultimately, a release of energy when this happens. First, we have to get over this hump. There has to be some energy input to actually break the sucrose apart. And then once we get it broken apart, ultimately the glucose and the fructose are going to have more energy available than the sucrose did. But the sucrose doesn't want to break, and we've got to put that amount of energy in. By adding an enzyme that's going to assist us in this process, instead of having to put in this giant amount of energy, the enzyme helping in playing... maker and speeding up this reaction, we have to put this amount. And so that's going to leave us, it saved us this amount of activation inefficient, and that's going to make this happen. So just like we had different factors that affected our enzyme reaction rates, we're also going to have factors that influence an enzyme. and it's effective. And some of these are going to be the same, but let's take a look at them. So first of all, temperature. So yes, increasing temperature is going to speed up the reaction. It's a catalytic reaction, enzymatic reaction, or temperature is going to increase reaction rate. However, you have to be particularly careful in enzymatic reactions because An enzyme is a protein, and since an enzyme is a protein, high temperatures denature, unfold, destroy. So you can increase your temperature trying to increase your reaction rate, but if you push it too far, if your Icarus can fly too close to the sun, wings may push the temperature too high, you denature your enzyme, and everything is ruined. The enzyme ceases to function, the reaction completely fails. can push temperature up but not into nature. Concentrations are also going to affect action. with enzymes just as concentration did those without enzymes. However, let's think about now the negative feedback aspect of concentration. We talked about negative feedback loops earlier, right? And so this idea of negative feedback is that eventually putting in so much reactants, or even if the reaction's been running a long time and there's a high concentration of products now, either way... there's a point at which this begins to hinder the reaction. So if you've got all these reactants and they're revolving around and revolving around, got to smack together in that proper orientation. If you start putting other couples and products, right, it makes it more difficult for those reactants to move throughout and each other. So at low concentrations, adding more concentration is great and speeds up the reaction. It is already full and jam-packed. If you're cramming people for space, right, then it's not official concentration. You can actually inhibit. Also, besides having reactive product concentrations, you can increase the concentration of the enzyme. We'll speed up the reaction rate once again to a point. So if all of your enzymes aren't busy making matches and doing jobs, then adding more enzymes, adding matchmakers into your reaction will speed up the process. If your limiting factor here is an enzyme number, if your limiting factor is availability of reactants, for example, having more matchmakers to kind of go in and help join won't do you any good. If there's no reactants to join. together. So, and then once again, having extra concentration of enzyme, extra matchmakers in the way in the environment, if they don't have a job to do, they're just bulky and in the way, clogging up space. For enzymes, something we didn't consider in our initial reaction rates, we want to talk about, okay, so once again, pH here is... penetration of H plus ions on a solution. pH is going to have an effect on the protein shape. So an enzyme is a protein, has this folded 3D structure, and we're going to...... only has its proper shape and its proper function. So, as I said, enzymes are specifically designed and tailored for us... And so that enzyme has a particular pH range, the pH of the environment that it was designed to work in, that it best operates. And if you put that enzyme in a different environment that it's designed for, that it doesn't automate effectively or efficiently, you're going to have very poor reaction rates. So for example here, enzymes work, say, in your stomach. We'll talk about, say, pepsin is a digestive enzyme in the stomach and pepsin works at an pH of around two that's an extremely pH scale goes from essentially one to fourteen so two is only extremely low so if you took pepsin and you took it outside of that acidic stomach environment to say just a regular pH of seven that enzyme is not its job. It's not going to catalyze reactions to those conditions because it's not going to shape and function to its job. So pH is important and pH balance is very important inside of your body. The enzymes in your body would stop working, which means you wouldn't be able to do any chemical reactions, which would mean. So just a couple of examples of how important. A single enzyme can be if your body is incapable of performing a single reaction thousands. So here's one of our little A&P in the real world verbs. Like I said, I love to kind of bring these in and give you some real handles on this information. So if you have an enzyme deficiency, so if your enzymes are working. functioning or your body and you have something wrong, your DNA mutation or something like that, and you don't produce this enzyme, then you can't catalyze the reaction. So, for example, Tay-Sachs disease is an enzyme deficiency. And what happens if you, it causes an accumulation of gangliosides in the brain. And eventually, if you can't get rid of the gangliosides, it ends up being toxic to the brain and it usually causes death. Also, if you've ever heard of the kind of the boy in the bubble or somebody that's severely immunocompromised, a severe combined immunodeficiency syndrome is also caused by the lack of an enzyme. And so that adenosine deaminase there, if you don't have that, you basically don't have an immune system. If you don't have an immune system, then you're basically living against some type of... infection, getting an infection virus, something like that. Then finally, our last example is probably the one you're most familiar with, and this is fetal ketoneur. If you have a child or infant, one of the first things they do when you have a baby is they immediately take them and they do a test to see if the baby is able to process phenylalanine. So if you don't have this enzyme you're not able to convert phenylalanine into tyrosine and if you have a buildup of phenylalanine it leads to mental retardation and seizures and so you can avoid this by simply through diet by simply not ingesting phenylalanine and so that's where the baby you see the baby formulas now that usually more expensive but we have these special baby formulas that say no pka on them right and The infant stuff, you'll see this, you know, there is marked for infants with phenylcutineuria. And that's what they're trying to do is through diet, right, avoid the ingestion of phenylalanine so it doesn't lead to the seizures and mental condition. So now we're going to kind of shift gears again here. We're going to next learning outcome, revisit, continue to revisit water throughout. force calls your body is 70 percent. One of these reactions we're talking about are happening in this aqueous environment and so the property is water. So this time we want to focus on reactions inside of your body is using body is taking heat. So the first thing that reason that body is kind of using water is that water absorbs heat. Changing significantly temperature. So that will basically use water as a heat sink. Your cellular respiration, where lots of energy, there's lots of reactions going on. And those reactions is going to be heat. These reactions that give off energy is going to be lost as heat. And so your body has to have a way of dealing. is basically being this giant and producing this heat uses water to soak um as like i said as a heat sink to kind of soak that also water carries heat with it when it changes from liquid to gas so now is this well this is how your body keeps cool so You go to sweat, leave the surface of your skin, and it carries the heat with it. So as it evaporates, it's actually going to cool. Your heat is going to be transferred. So that's a really important property. That's why sweating is effective for lowering. Also, water cushions and protects the body's structures. Okay, so we have your cells. field of our skin and it gives us that because it balance and buoyancy protection or is going as a so we want friction uh inside of our body you've got lots of cells rubbing against each other actions use energy and generate heat friction So we make sure and use water as a lubricating source. The other part that we're going to talk about while we're talking about water is hydration spheres. So we're going to be moving into talking about diffusion and osmosis. And one of the driving forces here behind osmosis is going to be hydration spheres. So basically, when you put ions in a solution, so let's say we had a beaker of water. water and we're going to put some table salt, right? Sodium chloride. We know that when we put the salt in the water that it's going to disassociate into ions, right? We're going to have a positively charged sodium and negatively charged chlorine that are now floating around in the water. So when we do that, because they are charged and the molecules that we've put them in are also polar, water is going to orient itself in a particular way. So the chlorine, right, that was neutral. negatively charged is going to have all the positively charged hydrogens side, the hydrogen side is going to towards the chlorine, which means it's going to want to put its negative side away from. And then the opposite is going to be true when we look at what's going on with the sodium. So in the sodium, you're going to see that we want the negative side. The water is going to be oxygen side that's negative will be turned towards the sodium. Nitrogens, heavily charged. So these have opposite, opposite orientations. So if you've ever wondered why do you throw salt in the water, why does it disassociate into these ions? Why doesn't it just snap together into sodium chloride and be salt floating around? How does it? dissolve. It's because once the, the pulls them apart, they get surrounded in these hydration spheres. So now there's these bubbles, these writers around. So now anytime I negatively charge, it has all natives out here on its surface. So and then on the outside, these sodiums, positives. So once these get watered, these balls, then these hydration spheres kind of get stuck in the sodium with each other to intentionally rejoin, right, as long as the water's present. If the anon that is not the surround but if this on was not completely and had some gaps where some more water The attract if we had other loose loose waters would come in here and into the slot if this wrapping wasn't because this is one of those driving forces. I'll do this a little. So I just showed you is a solvent. Solutions, right, universal solvent. That was, it had great cause. Here's where we're going to see this again, that water is a solvent for a hydrophilic solvent. loving or feeling it also means that it's going to be partially charged or it is going to be so this is where we get dissolves so what i mean by that like dissolves like is that what is right so therefore is going to dissolve polar So now let's start to talk about acids and bases. So some of our solutions that we have, we can talk about being acidic or basic. And so let's start with acids. An acid is an electrolyte. So remember that was a charged particle. We put ions into water. We have charged particles in the water. We said that that is... that that is now an electrolyte. So acids are an electrolyte because they're going to release this H+, this charged particle, into the solution. And so they are proton donors, right? H+, right? Hydrogen, proton donor. And so they're going to release these H-plus ions out into the solution. If we measure the concentration of H+, that is going to determine our acidity. And this is what we refer to as pH, that concentration of H plus ions. So in the bottom left here, we have HCl, that's hydrochloric acid. And if you put hydrochloric acid, when you add it to water, it disassociates into H plus and Cl negative. And that's going to give you a high concentration of H plus ions in solution. Just the opposite is to look at bases, okay? So bases are also electrolytes, okay? Why are they electrolytes? Because they ionize, disassociate in water, and are going to put charged particles into the water. Except the charged particle that is being put into the water here is a base releases OH negative or a hydroxyl ion. So acids released H plus, bases release OH minus. So the OH-concentration here, if you were to measure that concentration, is what's known as alkalinity. Now we usually talk about things in concentration of H plus ions. We usually refer to things in H. Alkalinity is more rarely measured, but if you're doing tests, like say for your swimming pool, for example, you've probably done an alkalinity test before. And what you're measuring there is the concentration. of OH minus the concentration of those hydroxyl ions that are present in the water. So you can see here on the bottom, NaOH is sodium hydroxide. It's a strong base. And if you take that strong base and you put it into water, it's going to disassociate into Na plus, sodium, and our hydroxyl, our OH minus. Earlier I mentioned if you take an acid and a base and you mix them together, meaning the H plus ions here were from... Acid, and you take your OH-here that were from your base, okay, add those together, you're going to get water. Because you're adding H+, and OH-, and that is H2O. So, the pH of solutions, as I mentioned, is determined by the concentration of H+, ions. My aside, pH is... Concentration of H plus I. So we have a scale of pH. I'm going to show you that goes from one in the center of our scale at seven. So water is a neutral pH. It's in that sitting right. So it's going to have a seven. So. If we have a solution that has a plus ions, we say that it is an acid that has an abundance of O, we say base. Here's our scale that I was talking about, and this is a base 10 scale. So notice here that as we go from 1 to 2, for example. to the minus one, ten to the minus two. So we're talking The difference in pH 1 and pH 2 here is a tenfold change. We're talking about an entire decimal place here, okay? So as we're going through, say, a difference here in 1 pH, I'm going to say the difference in pH 1 and pH 2, a single digit here, would be the same as, say, comparing a million H plus ions to 10 million H plus ions. It's a huge difference. So people say, oh, well, the pH is one, or pH was two, it was three, not a big deal, right? It's close. No, it's a massive deal. It's a huge miscalculation, okay? So pH is on a logarithmic scale, which means minor changes in the number of pH. It's actually massive changes in the amount of H plus ion concentration. So that's what I was saying. You're talking about a million H plus ions versus 10 million H plus. plus ions, right? And so, and that difference only gets greater as we go up in scale, right? That decimal place, that tenfold difference. So also this is a negative logarithm scale, and pH means H plus concentration. Once again, a higher H plus concentration. So that means that the H plus concentration, so this is 10 to the zero, and this is the highest. Down here at the bottom is 10 to the negative. 14 zeros before it. So don't be confused in the way the numbers that are written 10 to the negative 14 That's the really small number 10 to the zero. That's the so that means that a lower H plus Concentration means that you actually have a higher pH numbers that you're more basic. So H plus means So since we said that changes in very small changes on the pH scale are actually massive changes of H plus pH, the enzymes in your body are tailored at a specific pH. The body takes great care to resist any rapid changes in pH. pH would destroy your enzymes. If you don't have any enzymes, you can't do actions. chemical reactions be fatal. So your body has this buffer system in place and this buffer is going to try to prevent a rapid shift in the NPM. So buffers resist or prevent these rapid shifts. Does this keeping weak acids bases help maintain this equilibrium? So basically, let's assume that if you're pH is rising, pH rises, that actually means that your H plus concentration is actually low. So if your pH starts to rise, what you want to counter this, kind of in that negative feedback loop style, pH starts to rise to the set point, what you need to do is release some H plus ions into the solution. That's going... to increase the H plus concentration, H, and it's going to burn that set point right inside that opposite side if the pH starts to fall. So if the pH is falling, that what actually means is that our H plus concentration is now increasing. So how are you are you going to counter that? Well, you need to actually take H plus, right? Or you need to take H plus out of the solution. So you can do that by say, if you put in an OH negative base, hydrogen is going to burn and it's going to remove that H plus from the system. Top, you can see your blood pH levels, okay? And a happy, your normal and happy blood pH here is at 7.4, okay? Normal blood pH, hopefully there you can read that, is at 7.4. When you get above 7.45 or below 7.35, okay? So we're talking about plus or minus here, 0.05. Change in pH, okay? This is when your body starts to freak out and respond, right? This is, that green homeostatic range is about plus or minus 0.5. If you get outside of that, your body's going to start to respond and try to correct the problem, right? It's going to kind of go into panic mode. So when you go above 7.4, okay, you're becoming too basic, okay? And if you go below 7.3... 7.35, right? You're becoming too acidic, okay? So all the way down, if you enter, say, acidosis, okay, that's going to be this whole range from 7.35 down to 7.0. And that's that range where your body's going to be fighting to increase pH, right? That's going to be this bottom example here. So we were talking about in acidosis here. This is this bottom situation. So you want to bind up those H plus signs and get them out of there. And the opposite is true on the upper end. So this is the range, right, that your body can handle, that the buffer system works. What happens when you get outside of seven, okay, above 7.8, you've reached a range where this is probably fatal. So this is for buffering. So 0.5 here is your buffering capacity. Okay. Plus or minus as little as 0.4 can be fatal. So is there a big difference in pH 7 and pH 8? Absolutely. What's the difference in you being alive or being... So make sure even though they're tiny numbers... that you understand it's a logarithmic scale, which means we're talking about massive ion concentration. And also this is extremely important. So here's showing you how that buffer system works, right? Because we're just talking about looking at releasing H plus into the solution or binding H plus out of the solution to help counter the H change. So here's giving you the actual biological. system, and we can look at carbonic acid in the blood as an example of this. So if you have H2CO3, you have this carbonic acid in your blood, and if you need more H+, at least your system, right, to increase that H+, concentration, if you want H+, right, we increase that, means that our pH then we can shift this direction which is going to give us more available H+. This is a reversible chemical reaction. So what does that mean? On the screen, so I don't want to confuse you, but that means that I could use the backwards arrow and go the other way. So if I needed to raise my pH, if I needed to lower my H+, right? I could take those H plus ions out by adding by HCO3 negative right to the solution. I could actually take that H plus out and reform the carbonic acid and remove that H plus from the solution. So having these little buffering systems, these reversible reactions where things can flip between the carbonic acid, having the free H plus in solution gives your body a way to resist and to fight. Finally, how do we know what your pH is? So in the lab, we use a pH meter. It's a little probe you can actually put in the solution, and it will tell us exactly what the H-plus concentration is in that solution so that we can do calculation in the old-school pH indicators and some other ones that you might be seeing. I've seen before is litmus paper. So you see example of the And when you go in our laboratory section, you may see a couple examples where they show litmus paper and its function and just indicating whether something is acidic or basic. So in the center there, the center beaker is water. So if you put these two pieces of litmus paper, they make a red paper and a blue paper, and you put them in water, which is neutral, and nothing changes color. When you put the blue paper into an acidic mixture, you can see on the left there that the blue paper then turned red, meaning that was an acidic mixture. And then on the right, you can see that the red paper turned blue, blue meaning that that is a basic solution. We have more complex indicators than just kind of the yes-no acidic basic. Like you see with the pool test strips there where they kind of have this tricolor system. You can dip it in. And in the laboratory, these are the dip strips that we use quickly for experiments just to check the pH of a solution if you don't want to go through the most accurate process of actually going through and checking it with a meter. Finally, we were able to make these pH indicators, different solutions for a pH indicator. And there's actually one kind of through the third grade science experiment here. And you can make an indicator from cabbage juice. So if you take red cabbage and if you boil it, the pigments in red cabbage actually respond and the hydrogens actually bond here to the pigment. And depending on how saturated the pigment is with hydrogen ions, it's going to change the color here of the cabbage juice, which means it's a great indicator since it changes color depending on hydrogen. Hydrogen plus concentration, H plus concentration, we can use it as a grade. That is all for this lecture, so join me back next time.

And then we're going to look at the energetics of those reactions, whether they require energy input or whether they give off energy. Then we're going to look at some of the different factors that determine reaction rates. Okay so how fast Do these reactions occur under different circumstances? Then we're going to look at enzymes, what they do, why they're important.

We want to take another quick look at water and look at why it's important as a solvent and look at its polarity. And then we're going to look at acids and bases, specifically the concentration of H-plus ions in the solution as it relates to the pH scale. And then we... to look at a pH buffer system and look at how your body resists changes inside of pH. So starting with our notation and energetics, what we're going to be talking about is the energetics from chemical energy. So all the energy that you use in your body is chemical energy, things we get from breaking down bonds between chemicals.

So most of this energy, of course, is acquired from food for us. And all of the chemical reactions that are going on in your body are going to fall into two different categories, right? Based on whether they require energy input or whether they give off energy when the reaction happens.

So an endergonic reaction, endergonic reactions are going to require an input of energy, okay? So ender, right, is going to require an input. of energy for the reaction to proceed.

A reaction that is exergonic, okay, so exergonic, X here, EX, is going to release energy. The reaction proceeds. Okay, so let's look at this kind of in a graphical way.

So here's an example, here's our graph of what happens in an endergonic reaction. So we're going to start out with our reactants, that's the products that were the things that we're beginning with, the molecules that we're beginning with. And then we're going to have to input energy here into our system, right?

So you can see that this is going to require an input of energy here. And then we're going to create our products, right? And our products are what we end a chemical reaction with, right? So endergonic here, you can see we're going to require us to put this energy in. So what's a biological example here of an endergonic reaction, right?

One that you should be familiar with. Well, photosynthesis here is the classic endergonic reaction. So inside of photosynthesis, our products here, okay, will be here on the left side of our reaction. So we're going to, I'm sorry, I just think I just said that backwards. Let's start this slide over again.

So here we have a biological example of a endergonic reaction. and kind of the classic reaction for reaction is photosynthesis. So let's take a look at photosynthesis. So in photosynthesis, we're going to start with our and our reactants here, our CO2 and that are going to be created are going to be on our right side here. So this is going to require an energy input to Change these low energy products, the CO2 and energy product, right?

Plants get that massive amount of energy that they have to input into this process from capturing sunlight. So the sun is going, the question here, what plants get. So now let's flip over and look at an exergonic reaction. We're going to see that it's just the opposite, right?

So an exergonic reaction. is going to release energy. Okay, so now as we move from our reactants, right, which was on the left side of our equation here, that's what we started with, energy, and this is going to mark it being an exergonic. So let's look at a biological example of an exergonic.

Okay, this is what goes on in our bodies for cellular respiration. So now we're going to start with that glucose. Let's assume that you ate.

something sugary or carbohydrates and sugar, and you've taken in the glucose. Now we want to break that glucose down so that we can get the energy from it, that energy release from the exergonic reaction. So we're going to start with our reactants. So this time our reactants over here are going to be our glucose and our oxygen. We eat glucose with our food, we breathe in oxygen from the air.

And our products is going to be CO2 and water. and then the energy release. So then we're going to exhale that CO2 to get rid of it. We have the water in our system that we can excrete if we need to. And we've harvested now this energy, right, about, tells you there about 686 kilocalories of energy from breaking down this glucose molecule.

In all these chemical reactions, I was already using these names, but I didn't exactly define them for you. So I just want to give you... definition here when we're talking about the notation of these reactions.

The reactants are what I had on the left side of the equation here, and it's the substances that are entering into the reaction. Sometimes we have some intermediates. I didn't talk about intermediates here, but you might have some intermediate products that are just there temporarily for a short amount of time, and then eventually you'll get into your products, which is your final result, the end result of the reaction.

Let's continue this notation and look at a couple of classic chemical reactions. So we're going to have our reactants on the left. We're going to have our products on the right.

And we're just going to use some A and Bs here to represent basically any types of chemical compounds here. Just kind of use them as a generic form, kind of like you would in algebra. So a decomposition reaction is when we're going to start with two things, and they're going to... decompose and basically break apart into two individual items.

So a decomposition is going to start with an AB and that's going to decompose into A plus B. That is in direct opposition to a synthesis reaction, which is going to be the reverse of that. So that's going to be starting with an A and adding a B and then the product is going to be AB together. These reactions can be reversible.

as you see in the bottom right hand corner, and to denote a reversible reaction, we're going to put an arrow going in both directions. If that reaction was not, when we're not doing it, it is not a reversible reaction, we're going to draw a single arrow in the left to right, a direction indicating we're going from our reactants to our products. So if this is reversible, and this equation can kind of slide back and forth based on different factors and concentrations and other things that we're going to look at, Then it's said to be reversible and we denote that with the double arrow going in both directions.

Another classic reaction that we're going to see is an exchange reaction and we're going to see that in the bottom left hand corner there and that's starting with an AB plus a CD and then you're going to exchange those and so then you're going to end with something like AC and then BD. Okay so here's a couple of examples of reactions for you. Let's replace our A's and B's now and actually put in a couple of examples here for you.

So on top, you're going to see a reversible synthesis and decomposition reaction. So if we take carbon dioxide and make a carboxylic acid out of that, this is how CO2 is transported through your body and bloodstreams can be excreted at the lung. right so it needs to basically take co2 in its gases form convert it to something it can move this carbonic acid moves it through your and then it converted back to co2 for you to exhale an example of an exchange reaction and here you see what happens if you mix we have a hydrochloric acid and sodium hydroxide so we're missing mixing HCl here in a OH and if we have the exchange reaction here we're gonna exchange OH with the H, that's going to give us H2O, and ACL, which is basically salt. Mix an acid and base together, that's what you're going to get.

A little salt. We have been talking with a bunch of chemistry so far. Chemistry, intro chemistry is a prerequisite for the course. Kind of focus and move away from just kind of... their chemistry and start to focus on chemistry.

And so biochemistry is that combination of biology and chemistry. I mean, so we refer to it as the chemistry of life. So now we're going to start. Putting all of this, the chemistry and the reaction mechanisms that we looked at, in a organic, in a life-based setting.

And in that, we're going to find that the chemistry of life involves organic compounds. So an organic compound is a compound that's going to contain carbon that is bonded to hydrogen. So when you go to take organic chemistry, for example, it's all about these carbon-containing compounds.

Inorganic then are going to be compounds which do not usually contain lots of carbon, right, bonded to hydrogen. And there's some other examples there, you know, water, acids, bases, salts, right, those are just some examples of inorganic chemicals. I also want to highlight here, since you haven't had organic chemistry yet, that when we draw these different chemical compounds, and you're going to start to see some of those as we get into macromolecules and stuff in the next lecture, that we don't want to draw out the entire chemical structure because it's just way too complicated, way too much information that we don't. So organic chemists have a kind of shorthand version for drawing compounds, and this is the way you're going to see a lot of the compounds presented as we move forward. So just to refresh you on chemistry and make sure that you're not confused about the structures you see.

I want you to know and make sure that you understand that these two structures are equivalent to each other, meaning the hydrocarbon chain you're seeing on the left is exactly the line structure that you're seeing on the right. So how have we reduced that? Well, the way we're going to kind of shorthand this is we're not going to draw any carbons. What we're going to say is at the intersection of these lines, we're going to assume there's a carbon.

So if we go in and we put our carbon in, Everywhere that there's an intersection on these lines, we'll see that we have our six carbons, okay, the same six carbons that we have right here in the center of the compound. And then we assume that if there's not something properly written there, that that carbon is filled in with hydrogens, okay? So I can now go back and H on each one of these, right?

That carbon only had one connection. It wants four. So it needs three hydrogens. This carbon should have two hydrogens on it. So you could go through and fill all those in if you wanted.

But instead of having to draw all this and have all these carbons and hydrogens and have all this clutter in the way, it's much easier for us to be able to draw a simple line structure. Exactly. Exactly.

So as you start to see these carbon rings and these other structures coming up, all those carbons and all those hydrogens are there. It's definitely still an organic compound. We're just not drawing for simplicity's sake.

All right, so now let's kind of shift gears and start talking about what are the factors that influence reaction rates? Okay, so we've got some reactants. They're going to be converted to products, right? How quickly does this happen? A couple things that have to happen in options.

The first thing is, electrons have to come in physical contact. They cannot bond with each other if they don't leave each other and come. And the next thing that happens is they must overcome the pulse of force of their electrons.

So those valence shell electrons, right, going around the outside, we've got those positive and negative charges, right? So if they don't touch each other in the correct orientation, And if they've both got maybe a positive side and a negative side, and the two negative sides combine and touch each other, they're still going to get repelled. So not only do they have to come in contact, they have to come in contact in the right orientation and be able to overcome this repulsive force, right, of bringing electrons for each other, which is what's going to happen when two atoms are close to each other.

So our different factors that are going to influence these reaction rates are down here. And so we want to look at concentration, our reactants. The temperature the reaction is occurring at, okay? Our different reactant properties, right?

Solid, liquid, gas, things like that. And then is there a presence of a catalyst? So breaking these down, how does concentration influence a reaction rate?

In general, the higher the concentration, collisions you're going to have, so the faster the reaction rate. The concentration, the lesions, the faster reaction length. Low concentration means fewer collisions, means less probability of two things, you know, coming together in the correct orientation.

And so that's going to happen at a slower rate. There's a point where, this is all part of negative feedback, right? There is a point where you can increase the concentration so much that it starts to have a negative effect, right? But in general, especially at lower concentrations, increasing the concentration is going to speed up.

the reaction. We also need to consider our reactant properties. Okay, so let's talk about something, say, as a solution that's something that is solid. Okay, so reactions that take place inside of a liquid or inside of a solution, right, take place much faster than something in a solid. Why?

Once again, it's about number of collisions, right? So things that are molecules that are in a solid, they don't move very far or very fast, right? So their number of collisions is very low, right?

So anything that happens in a solid phase is going to have a much slower reaction rate than something that happens in the solution phase. Also, going back one slide here, let's take a quick look at the rusty car in the lower right-hand corner, right? And think about this as well.

Where does rust happen? Okay, so rust is a reaction. It's oxidation of metal.

And it happens where air, right, is touching that surface. Does rust happen in the middle of a solid piece of metal? No, it doesn't. Because there's not oxygen that is available in the solid piece center of the metal, right? So this reaction can only happen on the solid surface where it comes in contact with air, for example.

So that solid phase is going to limit reactions to only happening in the surface because in the interior nothing is available for reaction. We can also talk about temperature. So when you increase temperature, you increase the amount of kinetic energy in the system. So energy is not created or destroyed.

It has to go somewhere. So when you add temperature into the system, you're adding energy into the system. And that's going to result in kinetic energy of the molecules. It means they're going to move faster. So if they are moving faster, so a high temperature means that they're moving a lot faster.

If they're bouncing around very speedily, chances are that they run into somebody in the correct orientation, goes up the faster the particles. So that means things that are cold and slow, that these particles move slower. And that means that they're going to then have a lower or slower reaction rate in colder temperatures.

And then finally, we want to talk about the presence of a catalyst. So we're going to be looking at enzymes coming up, which are our biological catalyst. But inside all of chemistry, you can have a general catalyst. And a catalyst comes in and speeds up the reaction rate. And it does this by lowering the activation energy that's required for the reaction.

So remember on our graph when we were talking about an endergonic reaction, right, requires this energy input into it. A catalyst is going to lower that energy input that is required, making this matching process faster and more efficient. So catalysts are going to speed up. The presence of a catalyst is going to speed up this reaction rate. So, like I said, in our bodies, our catalysts are enzymes.

So enzymes are proteins that are inside of our body, and they want to lower that activation energy down and make this reaction process more efficient so that it happens faster. So how do they do that? Well, they're this reusable protein, and they are highly specific for a particular reaction. And basically they...

play matchmaker in this scenario and they help the reactants find each other in the proper orientation so that they can speed up the reaction and make it much more efficient, right? Which actually requires the energy that's required for it to happen because you're not wasting energy having things just randomly bump around and not run into each other in the correct orientation. So looking at a cat, at a enzyme here as a catalyst, on the right we have an example of an enzyme called sucrose.

Sucrase, sorry. So sucrase is the enzyme, and what it does is it takes sucrose, that's the substrate, that's the reactant that we're going to start with, and it actually breaks sucrose in half into glucose and fructose. So normally, this reaction does not want to proceed.

Once sucrose is together, it does not want to break apart. So if you want To acquire the glucose, say, that you've been having in your body as sucrose, and you need to break that back apart, having this enzyme available is going to make that a much easier and much more efficient process, and it's also going to speed it up because it is a biological catalyst. So here's the graphical representation, bringing those graphs back of what we were talking about.

So we had our energy of our reactants over here. And we're going to go through a process, and this is the energy of our products. Okay? So what we're doing here is this is actually an exergonic reaction.

Right? We need to get a release of energy, ultimately, a release of energy when this happens. First, we have to get over this hump. There has to be some energy input to actually break the sucrose apart. And then once we get it broken apart, ultimately the glucose and the fructose are going to have more energy available than the sucrose did.

But the sucrose doesn't want to break, and we've got to put that amount of energy in. By adding an enzyme that's going to assist us in this process, instead of having to put in this giant amount of energy, the enzyme helping in playing... maker and speeding up this reaction, we have to put this amount.

And so that's going to leave us, it saved us this amount of activation inefficient, and that's going to make this happen. So just like we had different factors that affected our enzyme reaction rates, we're also going to have factors that influence an enzyme. and it's effective. And some of these are going to be the same, but let's take a look at them. So first of all, temperature.

So yes, increasing temperature is going to speed up the reaction. It's a catalytic reaction, enzymatic reaction, or temperature is going to increase reaction rate. However, you have to be particularly careful in enzymatic reactions because An enzyme is a protein, and since an enzyme is a protein, high temperatures denature, unfold, destroy.

So you can increase your temperature trying to increase your reaction rate, but if you push it too far, if your Icarus can fly too close to the sun, wings may push the temperature too high, you denature your enzyme, and everything is ruined. The enzyme ceases to function, the reaction completely fails. can push temperature up but not into nature. Concentrations are also going to affect action. with enzymes just as concentration did those without enzymes.

However, let's think about now the negative feedback aspect of concentration. We talked about negative feedback loops earlier, right? And so this idea of negative feedback is that eventually putting in so much reactants, or even if the reaction's been running a long time and there's a high concentration of products now, either way...

there's a point at which this begins to hinder the reaction. So if you've got all these reactants and they're revolving around and revolving around, got to smack together in that proper orientation. If you start putting other couples and products, right, it makes it more difficult for those reactants to move throughout and each other.

So at low concentrations, adding more concentration is great and speeds up the reaction. It is already full and jam-packed. If you're cramming people for space, right, then it's not official concentration.

You can actually inhibit. Also, besides having reactive product concentrations, you can increase the concentration of the enzyme. We'll speed up the reaction rate once again to a point. So if all of your enzymes aren't busy making matches and doing jobs, then adding more enzymes, adding matchmakers into your reaction will speed up the process. If your limiting factor here is an enzyme number, if your limiting factor is availability of reactants, for example, having more matchmakers to kind of go in and help join won't do you any good.

If there's no reactants to join. together. So, and then once again, having extra concentration of enzyme, extra matchmakers in the way in the environment, if they don't have a job to do, they're just bulky and in the way, clogging up space. For enzymes, something we didn't consider in our initial reaction rates, we want to talk about, okay, so once again, pH here is...

penetration of H plus ions on a solution. pH is going to have an effect on the protein shape. So an enzyme is a protein, has this folded 3D structure, and we're going to......

only has its proper shape and its proper function. So, as I said, enzymes are specifically designed and tailored for us... And so that enzyme has a particular pH range, the pH of the environment that it was designed to work in, that it best operates. And if you put that enzyme in a different environment that it's designed for, that it doesn't automate effectively or efficiently, you're going to have very poor reaction rates.

So for example here, enzymes work, say, in your stomach. We'll talk about, say, pepsin is a digestive enzyme in the stomach and pepsin works at an pH of around two that's an extremely pH scale goes from essentially one to fourteen so two is only extremely low so if you took pepsin and you took it outside of that acidic stomach environment to say just a regular pH of seven that enzyme is not its job. It's not going to catalyze reactions to those conditions because it's not going to shape and function to its job.

So pH is important and pH balance is very important inside of your body. The enzymes in your body would stop working, which means you wouldn't be able to do any chemical reactions, which would mean. So just a couple of examples of how important. A single enzyme can be if your body is incapable of performing a single reaction thousands. So here's one of our little A&P in the real world verbs.

Like I said, I love to kind of bring these in and give you some real handles on this information. So if you have an enzyme deficiency, so if your enzymes are working. functioning or your body and you have something wrong, your DNA mutation or something like that, and you don't produce this enzyme, then you can't catalyze the reaction.

So, for example, Tay-Sachs disease is an enzyme deficiency. And what happens if you, it causes an accumulation of gangliosides in the brain. And eventually, if you can't get rid of the gangliosides, it ends up being toxic to the brain and it usually causes death.

Also, if you've ever heard of the kind of the boy in the bubble or somebody that's severely immunocompromised, a severe combined immunodeficiency syndrome is also caused by the lack of an enzyme. And so that adenosine deaminase there, if you don't have that, you basically don't have an immune system. If you don't have an immune system, then you're basically living against some type of... infection, getting an infection virus, something like that. Then finally, our last example is probably the one you're most familiar with, and this is fetal ketoneur.

If you have a child or infant, one of the first things they do when you have a baby is they immediately take them and they do a test to see if the baby is able to process phenylalanine. So if you don't have this enzyme you're not able to convert phenylalanine into tyrosine and if you have a buildup of phenylalanine it leads to mental retardation and seizures and so you can avoid this by simply through diet by simply not ingesting phenylalanine and so that's where the baby you see the baby formulas now that usually more expensive but we have these special baby formulas that say no pka on them right and The infant stuff, you'll see this, you know, there is marked for infants with phenylcutineuria. And that's what they're trying to do is through diet, right, avoid the ingestion of phenylalanine so it doesn't lead to the seizures and mental condition. So now we're going to kind of shift gears again here.

We're going to next learning outcome, revisit, continue to revisit water throughout. force calls your body is 70 percent. One of these reactions we're talking about are happening in this aqueous environment and so the property is water. So this time we want to focus on reactions inside of your body is using body is taking heat.

So the first thing that reason that body is kind of using water is that water absorbs heat. Changing significantly temperature. So that will basically use water as a heat sink. Your cellular respiration, where lots of energy, there's lots of reactions going on.

And those reactions is going to be heat. These reactions that give off energy is going to be lost as heat. And so your body has to have a way of dealing.

is basically being this giant and producing this heat uses water to soak um as like i said as a heat sink to kind of soak that also water carries heat with it when it changes from liquid to gas so now is this well this is how your body keeps cool so You go to sweat, leave the surface of your skin, and it carries the heat with it. So as it evaporates, it's actually going to cool. Your heat is going to be transferred. So that's a really important property. That's why sweating is effective for lowering.

Also, water cushions and protects the body's structures. Okay, so we have your cells. field of our skin and it gives us that because it balance and buoyancy protection or is going as a so we want friction uh inside of our body you've got lots of cells rubbing against each other actions use energy and generate heat friction So we make sure and use water as a lubricating source. The other part that we're going to talk about while we're talking about water is hydration spheres. So we're going to be moving into talking about diffusion and osmosis.

And one of the driving forces here behind osmosis is going to be hydration spheres. So basically, when you put ions in a solution, so let's say we had a beaker of water. water and we're going to put some table salt, right? Sodium chloride. We know that when we put the salt in the water that it's going to disassociate into ions, right?

We're going to have a positively charged sodium and negatively charged chlorine that are now floating around in the water. So when we do that, because they are charged and the molecules that we've put them in are also polar, water is going to orient itself in a particular way. So the chlorine, right, that was neutral.

negatively charged is going to have all the positively charged hydrogens side, the hydrogen side is going to towards the chlorine, which means it's going to want to put its negative side away from. And then the opposite is going to be true when we look at what's going on with the sodium. So in the sodium, you're going to see that we want the negative side.

The water is going to be oxygen side that's negative will be turned towards the sodium. Nitrogens, heavily charged. So these have opposite, opposite orientations.

So if you've ever wondered why do you throw salt in the water, why does it disassociate into these ions? Why doesn't it just snap together into sodium chloride and be salt floating around? How does it?

dissolve. It's because once the, the pulls them apart, they get surrounded in these hydration spheres. So now there's these bubbles, these writers around. So now anytime I negatively charge, it has all natives out here on its surface.

So and then on the outside, these sodiums, positives. So once these get watered, these balls, then these hydration spheres kind of get stuck in the sodium with each other to intentionally rejoin, right, as long as the water's present. If the anon that is not the surround but if this on was not completely and had some gaps where some more water The attract if we had other loose loose waters would come in here and into the slot if this wrapping wasn't because this is one of those driving forces. I'll do this a little.

So I just showed you is a solvent. Solutions, right, universal solvent. That was, it had great cause. Here's where we're going to see this again, that water is a solvent for a hydrophilic solvent. loving or feeling it also means that it's going to be partially charged or it is going to be so this is where we get dissolves so what i mean by that like dissolves like is that what is right so therefore is going to dissolve polar So now let's start to talk about acids and bases.

So some of our solutions that we have, we can talk about being acidic or basic. And so let's start with acids. An acid is an electrolyte.

So remember that was a charged particle. We put ions into water. We have charged particles in the water. We said that that is...

that that is now an electrolyte. So acids are an electrolyte because they're going to release this H+, this charged particle, into the solution. And so they are proton donors, right? H+, right? Hydrogen, proton donor.

And so they're going to release these H-plus ions out into the solution. If we measure the concentration of H+, that is going to determine our acidity. And this is what we refer to as pH, that concentration of H plus ions. So in the bottom left here, we have HCl, that's hydrochloric acid.

And if you put hydrochloric acid, when you add it to water, it disassociates into H plus and Cl negative. And that's going to give you a high concentration of H plus ions in solution. Just the opposite is to look at bases, okay? So bases are also electrolytes, okay? Why are they electrolytes?

Because they ionize, disassociate in water, and are going to put charged particles into the water. Except the charged particle that is being put into the water here is a base releases OH negative or a hydroxyl ion. So acids released H plus, bases release OH minus.

So the OH-concentration here, if you were to measure that concentration, is what's known as alkalinity. Now we usually talk about things in concentration of H plus ions. We usually refer to things in H.

Alkalinity is more rarely measured, but if you're doing tests, like say for your swimming pool, for example, you've probably done an alkalinity test before. And what you're measuring there is the concentration. of OH minus the concentration of those hydroxyl ions that are present in the water. So you can see here on the bottom, NaOH is sodium hydroxide. It's a strong base.

And if you take that strong base and you put it into water, it's going to disassociate into Na plus, sodium, and our hydroxyl, our OH minus. Earlier I mentioned if you take an acid and a base and you mix them together, meaning the H plus ions here were from... Acid, and you take your OH-here that were from your base, okay, add those together, you're going to get water.

Because you're adding H+, and OH-, and that is H2O. So, the pH of solutions, as I mentioned, is determined by the concentration of H+, ions. My aside, pH is... Concentration of H plus I.

So we have a scale of pH. I'm going to show you that goes from one in the center of our scale at seven. So water is a neutral pH. It's in that sitting right. So it's going to have a seven.

So. If we have a solution that has a plus ions, we say that it is an acid that has an abundance of O, we say base. Here's our scale that I was talking about, and this is a base 10 scale. So notice here that as we go from 1 to 2, for example.

to the minus one, ten to the minus two. So we're talking The difference in pH 1 and pH 2 here is a tenfold change. We're talking about an entire decimal place here, okay?

So as we're going through, say, a difference here in 1 pH, I'm going to say the difference in pH 1 and pH 2, a single digit here, would be the same as, say, comparing a million H plus ions to 10 million H plus ions. It's a huge difference. So people say, oh, well, the pH is one, or pH was two, it was three, not a big deal, right? It's close. No, it's a massive deal.

It's a huge miscalculation, okay? So pH is on a logarithmic scale, which means minor changes in the number of pH. It's actually massive changes in the amount of H plus ion concentration. So that's what I was saying. You're talking about a million H plus ions versus 10 million H plus.

plus ions, right? And so, and that difference only gets greater as we go up in scale, right? That decimal place, that tenfold difference.

So also this is a negative logarithm scale, and pH means H plus concentration. Once again, a higher H plus concentration. So that means that the H plus concentration, so this is 10 to the zero, and this is the highest. Down here at the bottom is 10 to the negative.

14 zeros before it. So don't be confused in the way the numbers that are written 10 to the negative 14 That's the really small number 10 to the zero. That's the so that means that a lower H plus Concentration means that you actually have a higher pH numbers that you're more basic. So H plus means So since we said that changes in very small changes on the pH scale are actually massive changes of H plus pH, the enzymes in your body are tailored at a specific pH. The body takes great care to resist any rapid changes in pH. pH would destroy your enzymes. If you don't have any enzymes, you can't do actions.

chemical reactions be fatal. So your body has this buffer system in place and this buffer is going to try to prevent a rapid shift in the NPM. So buffers resist or prevent these rapid shifts. Does this keeping weak acids bases help maintain this equilibrium?

So basically, let's assume that if you're pH is rising, pH rises, that actually means that your H plus concentration is actually low. So if your pH starts to rise, what you want to counter this, kind of in that negative feedback loop style, pH starts to rise to the set point, what you need to do is release some H plus ions into the solution. That's going...

to increase the H plus concentration, H, and it's going to burn that set point right inside that opposite side if the pH starts to fall. So if the pH is falling, that what actually means is that our H plus concentration is now increasing. So how are you are you going to counter that? Well, you need to actually take H plus, right? Or you need to take H plus out of the solution.

So you can do that by say, if you put in an OH negative base, hydrogen is going to burn and it's going to remove that H plus from the system. Top, you can see your blood pH levels, okay? And a happy, your normal and happy blood pH here is at 7.4, okay?

Normal blood pH, hopefully there you can read that, is at 7.4. When you get above 7.45 or below 7.35, okay? So we're talking about plus or minus here, 0.05.

Change in pH, okay? This is when your body starts to freak out and respond, right? This is, that green homeostatic range is about plus or minus 0.5.

If you get outside of that, your body's going to start to respond and try to correct the problem, right? It's going to kind of go into panic mode. So when you go above 7.4, okay, you're becoming too basic, okay?

And if you go below 7.3... 7.35, right? You're becoming too acidic, okay?

So all the way down, if you enter, say, acidosis, okay, that's going to be this whole range from 7.35 down to 7.0. And that's that range where your body's going to be fighting to increase pH, right? That's going to be this bottom example here.

So we were talking about in acidosis here. This is this bottom situation. So you want to bind up those H plus signs and get them out of there. And the opposite is true on the upper end.

So this is the range, right, that your body can handle, that the buffer system works. What happens when you get outside of seven, okay, above 7.8, you've reached a range where this is probably fatal. So this is for buffering. So 0.5 here is your buffering capacity. Okay.

Plus or minus as little as 0.4 can be fatal. So is there a big difference in pH 7 and pH 8? Absolutely.

What's the difference in you being alive or being... So make sure even though they're tiny numbers... that you understand it's a logarithmic scale, which means we're talking about massive ion concentration.

And also this is extremely important. So here's showing you how that buffer system works, right? Because we're just talking about looking at releasing H plus into the solution or binding H plus out of the solution to help counter the H change.

So here's giving you the actual biological. system, and we can look at carbonic acid in the blood as an example of this. So if you have H2CO3, you have this carbonic acid in your blood, and if you need more H+, at least your system, right, to increase that H+, concentration, if you want H+, right, we increase that, means that our pH then we can shift this direction which is going to give us more available H+.

This is a reversible chemical reaction. So what does that mean? On the screen, so I don't want to confuse you, but that means that I could use the backwards arrow and go the other way.

So if I needed to raise my pH, if I needed to lower my H+, right? I could take those H plus ions out by adding by HCO3 negative right to the solution. I could actually take that H plus out and reform the carbonic acid and remove that H plus from the solution. So having these little buffering systems, these reversible reactions where things can flip between the carbonic acid, having the free H plus in solution gives your body a way to resist and to fight. Finally, how do we know what your pH is?

So in the lab, we use a pH meter. It's a little probe you can actually put in the solution, and it will tell us exactly what the H-plus concentration is in that solution so that we can do calculation in the old-school pH indicators and some other ones that you might be seeing. I've seen before is litmus paper. So you see example of the And when you go in our laboratory section, you may see a couple examples where they show litmus paper and its function and just indicating whether something is acidic or basic.

So in the center there, the center beaker is water. So if you put these two pieces of litmus paper, they make a red paper and a blue paper, and you put them in water, which is neutral, and nothing changes color. When you put the blue paper into an acidic mixture, you can see on the left there that the blue paper then turned red, meaning that was an acidic mixture. And then on the right, you can see that the red paper turned blue, blue meaning that that is a basic solution.

We have more complex indicators than just kind of the yes-no acidic basic. Like you see with the pool test strips there where they kind of have this tricolor system. You can dip it in. And in the laboratory, these are the dip strips that we use quickly for experiments just to check the pH of a solution if you don't want to go through the most accurate process of actually going through and checking it with a meter.

Finally, we were able to make these pH indicators, different solutions for a pH indicator. And there's actually one kind of through the third grade science experiment here. And you can make an indicator from cabbage juice.

So if you take red cabbage and if you boil it, the pigments in red cabbage actually respond and the hydrogens actually bond here to the pigment. And depending on how saturated the pigment is with hydrogen ions, it's going to change the color here of the cabbage juice, which means it's a great indicator since it changes color depending on hydrogen. Hydrogen plus concentration, H plus concentration, we can use it as a grade. That is all for this lecture, so join me back next time.

Transcript for:Exploring Enzymes, Water, and Acids

Transcript for:
Exploring Enzymes, Water, and Acids