Hello everybody and welcome to chapter 2, chemistry. When you hear the word chemistry, you probably have some fear and some emotional responses take place because for some reason chemistry scares people. So hopefully by the end of our explorations of chemistry here, you'll be a little bit less afraid of the concept.
Our first slide here looks at three different versions of hydrogen. So we can talk about isotopes. An isotope of an element is a version of it that has a number of neutrons. That's the neutral charge particles.
It has a different number of those than the average or than the standard. So a standard hydrogen, the one here on the left, has no neutrons. A atom of deuterium is hydrogen. but it has an abnormal number of neutrons.
In this case it has one, so that makes it an isotope. So an isotope just means a different number of neutrons than you would normally expect. The third example here, tritium, is also hydrogen, but it has an abnormal number of neutrons as well, and it has two, so it's called tritium. All three of them are hydrogen, but they have different properties.
because of those differing numbers of neutrons. And not all isotopes, but many isotopes become radioactive as part of having an abnormal number of neutrons. Carbon-14 is probably one of the most famous of the isotopes.
It has normally a couple of neutrons with it, six neutrons. and carbon-14 would have a higher number than that to get up to that mass of 14. So a lot of times that particular element is used to try to figure out how old something is. When we look at things that are dissolved in water, we can have a solution, a colloid, or a suspension.
And the differences between them are really the size of the particles that are dissolved in the water. They're small enough that you don't see them, so they're not scattering light. There's nothing there to see necessarily because they're so small.
And they don't settle. So once it's dissolved into that solution, it's going to stay that way. And it's never going to settle out to the bottom of the container. The example here is mineral water.
So that water contains a number of dissolved minerals. that you don't see because they're so small. They don't settle out.
They stay there no matter what. A colloid is involving larger particles that are large enough to scatter light so you can see them, but they are not big enough to make them settle out. The classic example here is jello, and one really cool thing about the colloid known as jello is its consistency.
You know that Jell-O is sort of a squiggly, wiggly sort of thing that somehow or another hospitals always feel compelled to serve to every person in the hospital. Even though for most of the folks there, it's a horrible thing to have in their diet. But what's really cool about Jell-O is how you make it.
You add the powder, the magical powder, to water, and you heat up the water, and you stir it around, and then you let it cool off. And when it cools off, that, let's say, red liquid turns into a red gel. then you call it jello.
And if your kids are particular, you can get a specific shape of jello mold. So you can have Dora jello or Darth Vader jello or whatever kind of shape you want to have there. In the olden days, you just got a cup shape of jello and you called it good.
But let's say they don't like the shape. That's no big deal. All you would have to do is heat the jello up. It would go back to liquid.
pour it into a different mold, cool it off, it would go back to the semi-solid gel condition again, and you can do that back and forth quite a few times. So the temperature then determines the consistency of that particular example, and that's what makes jello so cool is its ability to change shape only based on temperature. Not all colloids do that, but that particular one is interesting in that regard. A suspension is when you have particles that are quite large, and large is relative here.
They are big enough that they scatter light so you can see them, and not necessarily see individual particles, but definitely tell something is there, other than just a clear water. And they're also big enough that they're going to settle out. So with gravity, they will not stay suspended. The biological example here is blood. So the test tube on the left of blood is fresh out of a person, it's mixed, and everything is suspended.
But if you give that a little bit of time, let's say you let it sit on the counter for an hour or so, or you put it into a centrifuge device which will spin it down within a matter of seconds, those red blood cells will be pulled to the bottom of the test tube by gravity. And what you see then is that blood is mostly water, the plasma part, and with only a small percentage, in this case around 45%, is red blood cells. So the suspension of blood only stays mixed when it's being stirred, when it's being actively pushed through the body.
So as long as you have blood flow in the body, you will have mixing and remaining of mixed blood in that condition. If you have poor circulation in some part of the body, you might actually get settling of the blood. and the separation of the red blood cells from the plasma, and that can become a problem. When we're thinking about chemistry, and then we start thinking about reactions, the question is, is this thing going to react?
Is it going to have a chemical reaction? And if so, how significant is it going to be? And so the simple way to know before you try it, if something is going to react or not, is to look at its electron shells or its electron orbitals. And here we see helium and neon are the two examples here. We find those on the far right-hand vertical column of the periodic table, and they're what are called the inert gases or the Nobel gases.
What that really means is that they're not reactive. So reactivity has two things really to consider. One is electrical charge.
Do the number of electrons equal the number of protons? So are our positive and negative charges balanced? If that's the case, from an electrical perspective, they are not reactive.
If the protons don't equal the electrons, then the atoms are electrically reactive. The second criteria here, and probably the one we spend the most time thinking about, is that full outer shell. that full outer area of orbit, is it full? Or does it have empty spaces in it? The helium example here in the first area of orbit only has space for two electrons, so it's as full as it can be.
It is not reactive because protons equal electrons, and the outer area of orbit is as full as you can make it of electrons. So it's really difficult to make helium do something. or to react with other things, because it's already as happy as it can be.
Neon, the example there, that second area of orbit can only hold eight electrons, so it has eight, and the protons and electrons equal each other. It is also non-reactive. And a neat thing about neon is we can run some electricity through it and make it glow. So you can tell if a business, at least in the olden days, was open or closed, or perhaps what kind of alcohol the local bar is serving by looking at the glowing neon in the window.
So those not being reactive are useful because of their lack of reactivity. Reactive elements are those that don't already have protons equaling electrons, or they don't already have a full outer area of orbit. So most of the elements in the periodic table, aside from that far right-hand vertical column, are going to be reactive somewhat.
The farther away from being electrically satisfied and or having a full outer area of orbit, an atom happens to be the more reactive it's going to be. So some chemical reactions think mixing table salt in water. Do you see anything happen? No, you don't, because while a reaction is occurring, It is a very, very mild reaction, so it doesn't produce any visible outcome.
If you mix vinegar and baking soda, you see something happen. We would call that a relatively mild, starting to get into the moderate chemical reaction category. We can see something happen there because those molecules, those atoms, are reacting dramatically enough, trying to get everything sorted out, that we can see it.
Perhaps a much more violent and dramatic reaction would be what happens when you mix white phosphorus with water. Now normally you would think mixing water with something would make it non-reactive, would stop a reaction, would stabilize it, but in this case water is the trigger for a very violent, powerful explosion. So white phosphorus burns very, very violently and very, very hot. when it's exposed to water because that is a way for the white phosphorus to reach a level of stability, to get electrically satisfied, to get a full outer area of orbit.
And it had a lot of work to do. In the process, it was very, very noticeable. Something like a pound of white phosphorus and perhaps 10 gallons of water would make an average-sized office building disappear from existence. So this is very, very unstable stuff. to the point that you would not want to open a container of white phosphorus on a humid summer day because the simple humidity of the air might cause that container of white phosphorus to react.
So, again, some reactions quite dramatic, others not so much. Now, unless you're working with phosphorus grenades in the military or underwater welding or explosives, you're probably not going to run into white phosphorus. So you probably wouldn't need to worry about that.
But something like mixing two different kinds of cleaners. Let's say you have a chlorine-based cleaner and an ammonia-based cleaner in your cleaning cabinet, and you say, oh, well, two good cleaners. If I mix two good cleaners together, I should get a super cleaner.
And what you get is a super killer, because the gases that are produced from those reactions of those things, which should never mix together, can be fatal if you don't get out of it in very short order. If you've ever tried that and didn't die, you learned that it's really nasty stuff, so don't mix those things together anymore. If you had drawn out those elements on paper, in the format you're seeing here, you could have looked and seen that they don't have outer areas of orbit that are full.
Perhaps their positive and negative charges aren't balanced. There is going to be a reaction here, and perhaps we shouldn't do that. So drawing it out on paper is always a safer way to check that sort of thing.
Molecules have shapes, and those shapes are determined by the kinds of bonds that are present. You can have both of these types of molecules here, carbon dioxide and water, both have covalent bonds that are holding them together. And in the covalent bond video, you learned all about that. But...
the different kinds of covalent bonds determine the shape. In this case, carbon dioxide is one atom of carbon, two atoms of oxygen, held together by double covalent bonds on each side of the carbon. So carbon had four empty areas of space in its outer orbit, and that needed to be filled. So oxygen, each having two empty spaces, was able to share two sets of electrons between each oxygen and the carbon. So when you're sharing two sets of electrons, rather than just one set, that's a double covalent bond.
This particular example equals nonpolar. So nonpolar means the charges are equally shared throughout the molecule. There's not a positive end or a negative end like you would see on a magnet.
With the water molecule, at the bottom of the screen here, the oxygen shares two sets of electrons, one with each hydrogen. Everybody gets happy that way, but the sharing of charges within the molecule isn't equal. What you find is that the oxygen pulls on those negative electrons a little bit harder than the hydrogens do, so that means the oxygen end is slightly negative, the hydrogen end is slightly positive. So now we have a magnetic positive and negative pole situation.
This unique characteristic of polar covalent bonding, is what gives water all of the very unique characteristics that it has. So water molecules actually attach to each other in this fashion. A negative oxygen from one molecule is attracted to a positive hydrogen from another molecule. As you can see here, each water molecule is capable of hanging on to multiple other water molecules all at the same time. Each individual attraction between a negative oxygen and a positive hydrogen is a relatively weak attraction, but there are so many of them within a particular unit of water that overall it makes a very strong, cohesive set of attractions.
You can see the insect here in the picture actually standing on water, and you can see the depressions under each of its feet, meaning that it's actually pressing the surface of the water down a little bit. But all those individual hydrogen-oxygen attractions that it's standing on are strong enough to hold it up. As humans we really haven't figured out a way to reliably be able to do this because those molecule attractions are not strong enough generally to hold us up.
Now you will notice if you were to jump into a swimming pool and you happen to hit at a little bit the wrong angle you'll discover that well water does not readily break those bonds and let you through. So I know it says in the book that water serves as a cushioning agent. That is definitely not correct. Water isn't a cushioning function really because something that cushions needs to be compressible.
It needs to be squishy. Water is not. Water is very unsquishy. So if you need a cushioning agent for the body, fat is a much better option for that. We can have different kinds of chemical reactions occur, and the types vary based on what's happening.
In a synthesis reaction, the objective is to build larger molecules. So in this case, let's say we're trying to build a protein. So we have amino acid molecules, things like glutamate, and proline, and valine, and threonine, and tryptophan, and others that you've probably never heard of before. If we take a lot of those, we can put them together into a larger molecule. We can synthesize, in this case, a full protein.
So a synthesis reaction builds larger molecules. And often, but not always, you can tell which type of reaction you're dealing with by the temperature. And often, a synthesis reaction will get colder because it's taking energy from that area and storing it.
in between those molecules as they're attached. The second kind of reaction here is a decomposition reaction. This occurs when you have a molecule that is broken down or decomposed into smaller pieces. So the example here is glycogen, which is an animal energy storage molecule in the blood, gets broken down into individual glucose. So the objective here would be to release energy, to generate some energy.
for some sort of thing to occur. And often, you would expect the temperature for a decomposition reaction to increase, as the energy that was trapped between those individual particles is released as they're broken apart. The third option here is an exchange reaction, where both synthesis and decomposition are occurring.
So basically, you're rearranging. You're taking what you had and reconfiguring it. to make it into something a little bit different. So reactions are going to be one of those three scenarios.
When we talk about acids and bases, we're talking about things that we measure as pH. So when we talk about the pH of something, what we're really talking about is how much hydrogen does it have in it. And we're always comparing hydrogen to hydroxide, or OH. So the H to OH ratio. And the more hydrogen there is relative to the hydroxide, the more acidic it is. The more hydroxide there is relative to hydrogen, the more basic the substance is.
And we can measure those substances on a pH scale that goes from 0 to 14. Anything below 7, so between 0 and 7 is an acid. Anything between 7 and 14 is a base. So really what we're saying is if it's below 7 on the pH scale, it has more hydrogen than it has hydroxide.
And the more acidic it becomes, the more hydrogen it has relative to the hydroxide. Above 7, that means we have less hydrogen than we have hydroxide. And the higher we go towards 14, the more hydroxide we have relative to hydrogen. And so 7 then would be hydrogen equals hydroxide.
The pH scale is a logarithmic scale, and what that means is that when we go from 7 to 6, we didn't change by a factor of 1, we changed by a factor of 10, and each number compounds by a unit of 10 from there. So if we were to look at something that had a pH of 7, it was perfectly neutral, and we were to ask how much more acidic is black coffee than let's say pure water at a ph of seven if black coffee has a ph of five the water was seven before this discussion you would have said the coffee is two times more acidic than the water. Now perhaps you're thinking it's 20 times more acidic because if each number represents a unit of 10, 10 plus 10 equals 20, but that's not right either. Remember we said this is a compounding scenario.
So from 7 to 6 is 10 times more acidic. From 6 to 5 is another 10 times. So from 7 to 6, 10. From 7 to 5 is actually 100. If we were to go from 7 to 2, so we're talking about pure water compared to lemon juice or stomach acid. From 7 to 6 would be 10, to 5, 100, to 4, 1,000, to 3, 10,000, to 2, 100,000.
So what we would say is that lemon juice or stomach acid is 100,000 times more acidic than pure water. Now we're talking big differences. If before this I had said that blood was normally a pH, as we see here, of 7.4, and it were to go to 8.4, you would have perhaps replied, so what? It changed by 1. No big deal. Except now we know it changed by a factor of 10. So the blood at that point would be 10 times more basic than it was supposed to be.
So if the pH went from 7.4 to 7.5, That would be a 1 times change. Going all the way to 8.4 would be a 10 times change, and at that point, it doesn't matter how much it changed, you're most likely dead. Your body doesn't really tolerate large swings in pH very well, especially if it doesn't go back quickly. So all kinds of different examples here in real life and where they would fall on the scale. The good news is that your body has a number of actually three different buffering systems, whose job is to keep the pH of things where it's supposed to be.
So a buffer is a very unique compound that can act like an acid, or it can act like a base, depending on what you need. If the body is becoming too basic, the buffer will act like an acid, and basically remove hydrogen, or rather add hydrogens to the scenario, increasing the hydrogen to hydroxide ratio. If the body's becoming too acidic, the buffer is going to act like a base.
It's going to actually absorb hydrogens from that solution and bring the body back in a basic direction. So a buffer can release hydrogen or it can absorb hydrogen, acting like an acid or acting like a base, to keep the body's pH where it needs to be. And for the most part, the body does a really good job of that.
And generally, you don't have too much in the way of problems. Most of the time, if the pH gets off very much and causes problems, that's a result of excessive physical activity and perhaps some sort of extreme metabolic scenario. So, usually, not a problem for a healthy person.
Some macromolecule chemistry would involve things like carbohydrates, proteins, and fats. So... the way that these molecules are assembled, it's going to be a synthesis reaction because we're building something large from small things, is going to be what we call dehydration synthesis.
So let's say we have two different things that we want to put together. Let's say the first one is glucose, the second one is fructose. And by themselves, they're stable.
They have full outer areas of orbit. They have electrical positive. protons, negative electrons equaling each other, so they're non-reactive. To make them reactive we have to take away some sort of stability. So what if from the glucose in the green here we were to remove an OH?
That would cause the carbon, if we go down here to the bottom we see each of these points would have represented a carbon, so a carbon atom right here would no longer have been sharing electrons with an oxygen. That would leave an empty space in the outer area of orbit for carbon, so now glucose has become reactive. If we took fructose, and we can see down here that it had a number of carbons as well, again, one at each point, and if from that scenario we had an OH here, what if we take off an H?
So that then makes the oxygen reactive. Then the oxygen and the carbon from our glucose, could get together as we see up here at the top. They would form a covalent bond between the oxygen and the carbon.
forming, in this case, sucrose as the end product. In the meantime, we've removed OH from one side, H from the other. When we add those together, we get H2O, or water. So by removing water, that's dehydration, we built something.
We synthesized. So dehydration synthesis really means to remove water that then causes those molecules to become reactive and get together to form something different. What if we want to break them back apart again? So we formed it as part of some sort of process, and let's say the body wants to break those sugars apart from the sucrose back to the glucose and the fructose, so then we could use it for energy.
So if we built it by removing water, what do you think would happen if we added water back in? Hopefully you're thinking that would cause the sucrose to break apart, and return to its original glucose and fructose by returning the OH to the glucose and returning the H to the fructose. And that would be the correct answer.
So it's very simple to build carbohydrates. It's also very, very simple to break them apart and get the energy from them. And this is why the body loves carbohydrates.
You like them because they taste good, because really they're sugar. The body likes to work with carbohydrates because it's so easy to break them apart. So a healthy diet, in my opinion, can contain up to 60% of your total daily calorie intake being carbohydrates, and your body will find that to be very easy. You've no doubt heard of things like the Atkins diet, or some of the other low-carb, no-carb, I guess keto is the catch diet of the week. And those diets are focusing on keeping carbs away from the body.
Starve the body of carbs. Force it to use protein and fat for energy. And conceptually, that makes sense because it's very difficult for the body, relative to carbohydrates anyway, to get energy from fat and protein.
So the body is working harder than you lose weight. The problem is it's not always... properly choosing which proteins and which carbohydrates to break down. And sometimes in those keto sort of scenarios, the body actually starts eating itself. Rather than metabolizing the fat you want to get rid of, it starts eating muscle.
It starts eating other parts of the body that you didn't want to have happen. So I wouldn't recommend those sorts of extreme carb-avoiding diets because the body doesn't always do a proper job of seeking its alternate energy source. and carbs are just so much fun to eat anyway, why would we want to avoid that?
Some of you perhaps are carbohydrate addicts, and you know who you are. In our previous life, when you could go to a restaurant and sit down at a table, some restaurants would bring baskets of bread to the table, and you know who you are. You would pick the restaurant based on what kind of bread they brought to the table.
In other words, what kind of carbohydrate were you in the mood for? And if you're anything like me, you would get your money's worth on eating that supposedly free bread before they ever brought you the main course. If we look at carbohydrates, they come in three flavors.
Monosaccharides, disaccharides, and polysaccharides. Monosaccharides means one sugar. So it's an individual molecule.
It can be glucose, fructose, galactose, deoxyribose, and ribose, as you see across the top here. Disaccharides means two sugars, so two monosaccharides hooked together. In our previous example, we saw glucose and fructose get together to form sucrose.
If we had two different glucose molecules together, that's called maltose. Or if we put a galactose with a glucose, we would call that lactose. So those different kinds of sugars start to get into the category of some people can't have them. So you perhaps know, and hopefully aren't yourself, lactose intolerant people. If you're lactose intolerant, what that means is your body doesn't know how to break down lactose into galactose and glucose again.
It's missing the enzymes that it takes to break those molecules down. What that really means for your life is that you can't have real dairy. So real cheese, real milk, things like that are off your list.
Unfortunately, that means pizza is not an option. Ice cream is not an option. All of the wonderful things in a normal diet aren't available.
Then you have to switch to something like almond milk. And my question has always been, how do you milk an almond? Where does the milk come from? And I do know if you crack it open inside, I've never seen milk in there before. So that's a great mystery to me as to where almond milk really comes from.
But we'll just roll with it and pretend that it's real milk for those of you who don't have a choice. Polysaccharides are long chains of monosaccharides hooked together. The glycogen example we saw on a previous slide is a polysaccharide. So poly means many. So many...
monosaccharides hooked together forming a larger chain of something. In the world of fats, we build fats just like we talked about with dehydration synthesis. So in the triglyceride formation up here at the top, we see the removal of water here resulting in our end fat product over here.
So carbohydrates, fats, and proteins all use dehydration synthesis. The middle picture here is a phospholipid molecule. And this is a really important fat because this is what makes up cell membranes.
We'll get to cell membranes in the next chapter, but they're really important things. So without enough fat in your diet, you would not be able to build cell membranes. So sometimes people think if I could eliminate fat from my diet, I would be healthier.
And that sounds good, but I've just told you, you wouldn't be able to make cell membranes without having some fat in your diet. So don't go fat-free. That's not only boring, fat tastes really good, but it's also going to starve your body of some things that it needs. Additionally, your body needs fats in the form specifically of cholesterol, as you see in the bottom picture here, and you've heard perhaps that cholesterol is bad for you.
That's not really the case. You can have too much, obviously, and that would be a problem. But you need cholesterol in the body so that you can build some pieces of cell membranes, and cholesterol is also the starting molecule for testosterone and for estrogen.
So if you want to express as a male or as a female, you sort of need these fats so that your body can make those sex steroids. What you often see in very, very thin female model types, is they're sometimes lacking in female body figure because they don't have enough fat in their diet to build that shape and to produce enough sex steroids to express some of the female sexual characteristics that normally identify an individual as being female when you would look. Here's that phospholipid, so making up the cell membrane up close and personal here.
And there's the cholesterol a little bit closer. And if you were to take an image of testosterone or estrogen and lay it over the top of cholesterol, you'd find an almost exact match. So the difference between cholesterol and the estrogens and testosterone is very, very little. And even within testosterone, looking at it compared to estrogen, there are very, very few differences.
So very small differences in very small molecules make huge differences. in outcome and in product. Proteins.
Proteins are relatively complex assemblies of molecules, also built by dehydration synthesis, but the important question is here, how do we build a protein that is functional? So proteins come in four different flavors, or shape, structure, combinations, and the first is a primary structure. A primary structure is simply a chain of amino acids. So those things we mentioned earlier, the glutamates, the leucines, the threonines, all that good stuff. Just hook a string of those together makes a primary structure.
But a protein does its job based on shape. And each type of protein has to have a unique shape. And you can't get thousands of unique protein shapes from a primary structure.
So we take the primary structure and use it to form a secondary. And as you see here, a secondary structure is taking the primary and coiling it or folding it, or perhaps both. This then starts to give us unique shape, but not enough to actually form a functional protein.
So we would then take a secondary structure and coil it and fold it some more to form what you see here as a tertiary structure. For some proteins, tertiary structure is sufficient. It forms a functional protein.
But some proteins need to go one step further to a quaternary structure. And a quaternary structure is simply two or more tertiary structures assembled together in a larger structure. This gives very, very complex shape and allows for the formation of thousands of unique shapes to form all the different types of proteins that the body needs to function.
So a functional protein occurs at tertiary, perhaps, or at quaternary, but not before. Primary and secondary would just be intermediate steps getting you to a functional protein. You've heard of enzymes, but perhaps you don't really know what they are. An enzyme is a protein, and its specific job is to increase the rate of chemical reactions, make them happen faster. If you think about what you might have had the last meal that you consumed, think about what you ate and how long it's going to take your body to get the energy out of it, to carry out the reactions of digestion and metabolism.
And the answer for that really is a couple of hours. The food is in the body typically no more than 24 hours, So in that time, you have to do everything with it that you can. So with enzymes, as you can see in the second picture here, the energy it would take to achieve a particular reaction is much less than it would take without that enzyme present. And it takes a much shorter period of time to get to the end product. So with enzymes in your mouth, for example, back to that delicious bread item you're eating at your favorite restaurant, you can chew a...
a mouthful of bread, and in a matter of seconds, the enzymes and saliva had digested most of that carbohydrate to the point where you feel like you started with a full mouth of bread, and now there's not much left. So that bread was almost completely digested in a matter of seconds in the mouth with enzymes. Without enzymes, you perhaps could still get to that end product outcome, but it would take a lot longer. If you are a Star Wars fan, you perhaps would recall in the first three movies, which were actually the second three, but we didn't know it until the second three came out, that Luke was captured by the Jabba the Hutt terrorist worm.
And the worm went and took him to drop him off in a pit, and at the bottom of that pit was a monster. And that monster did not have enzymes in its digestive system, so when it swallowed its prey, it would take thousands of years to digest it. obviously an inefficient process. And we don't have even days or weeks to allow our system to slowly digest things.
We certainly don't have anywhere in the body to store all that material, a week's worth of intake to store it while it's processed. So with enzymes, things work pretty well. Without enzymes, you may or may not be able to finish something in the time frame that it really needs to happen in. So without enzymes, the heart.
cannot function properly. If you overheat, you could have a heat-induced heart attack because the enzymes helping the heart to function would become inactivated. So proteins can actually lose their proper shape. If they lose their shape, they lose their function.
And things that can cause them to lose their shape, and we say they are denatured when they lose their normal shape, might be things like temperature getting too hot or too cold. It might be salt concentrations getting too high or too low. It might be the pH of the surrounding tissues and fluids that gets too high or too low. So if any of the parameters in which the cells are living get off, enzymes and proteins might lose their function, and it could go as far as cause death or certainly cause one to feel unhappy. If you've ever experienced heat stroke or heat exhaustion, you know exactly what we're talking about here.
And essentially the body overheated and the enzymes started to lose their function. As long as you catch it before it's permanent, the enzymes and the proteins will return to their normal shape and function. It might take a couple of days or weeks depending on how badly you messed it up. If you boil an egg, you are heating the egg until the protein becomes permanently denatured.
And once an egg is completely boiled, it will never go back to liquid inside again. So in that case, when you're cooking your food, sometimes you denature the proteins. as just a function of cooking the food.
Think of your body overheating as cooking. Here's an example of how an enzyme actually achieves the speeding up of the reaction. The purple enzyme we have here is going to grab onto things that need to react. So for two different molecules to react with each other, they must bump into each other. And they must bump into each other at exactly the right angle.
where their reactive areas will be perfectly aligned. If you wait for that to happen just by random chance, it might eventually get there, but that's pretty low odds. So the enzyme captures each of the particles, lines them up perfectly with each other, so that their reactive areas are pre-aligned, the reaction occurs, then the enzyme releases the product, and away you go.
So back to the idea of the reactions in our body. Might they eventually randomly bump into each other? Sure.
But you might be days or weeks waiting for that to occur. So the enzyme ensures that every time those two particles touch each other, they are perfectly aligned. The reaction occurs, and life goes on very nicely. DNA is a molecule that is made of some sugars and some things that we've talked about a little bit. But here's a close-up view, the double-stranded DNA molecule, and what you find up here at the top of the screen is this idea that there's a lot of stuff.
There's a phosphate group. There's a sugar group. There's some protein component to this. And so really we're saying DNA is a very complicated molecule from a chemistry perspective. We'll talk a little bit more about DNA and what it does later in your anatomy experience, but for right now, we're saying the chemistry of it is complicated, which is why many people spent many years trying to figure out what the shape of DNA was, and they were able to eventually do so based on the chemistry.
They were able to say, here are the molecules involved, and they can only bond with each other in this particular pattern, and so they were able to deduce, basically by working chemical reactions on paper, the shape and then eventually we're able to verify that with some other techniques. So if we look at that individual basis here, the two strands of DNA, the adenine and the thiamine in this case, we can see a lot of covalent bonds going on within each molecule and within the two themselves. And these little dots in the middle are indicating some hydrogen bonding.
that are actually holding the two strands together with each other. So everything about DNA and how it works is really a chemistry problem. We can look here at the bigger picture. DNA is basically just a long string of these hydrogen bonds.
Remember, that's an attraction between the positively charged hydrogen and a negatively charged something else. going on here in this very important molecule and certainly very complex molecule after you've watched the other videos that i've posted for chapter two that will wrap up your chapter two experience so hopefully you learned a lot about chemistry here at least enough to no longer be scared of it but perhaps respect it a little bit more than you maybe did before If you have any questions, make sure you post those in the Unit 1 discussion board, and I'll see you next time.