a guest Nov 13th, 2018 82 Never
- BI222, Video 2
- You know, we've already talked a little bit about some of the polymers in our body. For example, you know that this monomer, this monosaccharide, if you will, called glucose, can form really long chains of things, which we can call—if there's two of them, we call it a disaccharide, like table sugar. Or if you put a bunch of them together you can have polysaccharides like starch and glycogen which store energy and cellulose which is used for structure in living things like plants specifically a plant cell wall or something like that. But I don't want to give you the impression that it's all about carbohydrates, okay. I want to talk to you about some other cool things. All right?
- Now here's something. This is always fun, man. Don't run away when you see this. This is not as scary as it looks, okay. Look at the size of this baby. This is a fat molecule, all right, and it belongs to a group of molecules called lipids, and I want you to understand what we—I mean, if you—you know, structure follows function, and I'm going to talk to you about lipids in a second, but look at all the bonds in this thing. What would this be perfect for? Well, this is kind of a storage molecule, isn't it? And that's what—one of the functions of lipids.
- You see, lipids—there are, really there's a bunch of different things in lipids, but the three that are most important are the fats, okay, and fats and oils are used in bodies to store energy. So for example, corn oil, you know, we squeeze corn to get the corn oil out of there, and that literally is used to store energy. Oils can also be used as waterproofing materials too, okay.
- Which brings us actually to a third type of lipid, waxes. Now when you think of wax, and where do you find wax? Well, we find it in our ears, and indeed, it's a protection there. It's to make it sticky so things get stuck before they go in your ears, like creatures. Not like cats, I mean, but like, you know, small bacteria and things like that. So these are for protection. Plants use waxes for protection.
- So the lipids, you know, it's really about storage and waterproofing, is really what it's about. We even use these in our cell membranes, to produce that—maybe you've heard the term hydrophobic layer, that waterproof layer on the outside. Well, there's also a group of things—so that's, that—that's another polymer that's very important. Well, how about a third polymer? Have you heard of the term nucleic acids? Now nucleic acids are found in the nucleus of the cell, and they have a name that ends in nucleic acid. There's one called deoxyribonucleic acid, and ribonucleic acid, okay. Well, these two things are incredibly important in the way our bodies work, because these things control our genetic abilities. They literally give you the traits that you pass on to your offspring, and give your cells the traits that your cells pass on to their offspring. So that's another polymer.
- So what have we seen? We've seen starches, polysaccharides in other words. We've seen sugars, carbohydrates in other words. We've seen lipids, and now we've seen nucleic acids. But you know what? The real workhorse of your body, the thing that works the hardest to keep you going is a group of things called proteins. And proteins work in a lot of ways. They work as structure, but they also work as something called enzymes, and enzymes are the coolest thing, because they act as something called a catalyst. Now you may have heard a definition of a catalyst is something that speeds up or slows down a reaction, but doesn't change.
- Let me show you how that would work with a protein. I'm going to draw the wolf model of an enzyme. There it is. Now this is catalyst. Now this thing will work with something called a substrate, and I'm going to take a substrate, and I'm going to take this and I'm going to put it in there, and I'm going to take this and I'm going to put it in there. Now look what's going to happen. This is going to react with them, and it's going to put them together by a bond. And yet, the enzyme, the catalyst itself, will not change. It will look exactly the same when it's done.
- So think about this. These proteins can actually change something without themselves changing, and that's a catalyst, but if you think about it, now we can think of why catalysts work the way they do. For example, somebody once noticed that the warmer you make these things, the more likely they are to function. Why? Think about it. If this is warmer, it's moving faster. If it's moving faster, it's going to do this reaction faster. We've also noticed that if we make it too warm, the thing is going to not work. Why? Because it twists and this active site doesn't work anymore, okay. Well, then—so temperatures is a function of this. If we change the pH, if we make it more acidic or basic, what's going to happen? Well, this active site may not work as well. It's specific. You know, this whole idea of enzymes and proteins being the workhorses of your body, if you think of them as catalysts, you can really see why they are just that.
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