[Music] Hi everybody, it's your AP biology teacher Mr. Poser. Today we're getting into AP biology topic 1.3 and that is the on the introduction to macroolelecules. We got a little bit of an introduction to macroolelecules in our last video that was on 1.2 the elements of life. We talked about how carbon, hydrogen, oxygen, and in some cases nitrogen, phosphorus, and sulfur um are the primary atoms that make up all the different biological molecules that make up living things. And those are your carbohydrates, proteins, lipids, and nucleic acids. Our four next subsequent lessons after this one are about carbohydrates, proteins, lipids, and nucleic acids. Um but first, we got to get into a little more introduction into macroolelecules because what actually is a macroolelecule? Well, macro means big. Um, so big molecules, all right, how are those made and how are they broken down? That's what this is going to be about here. Hence these two little pictures here, the breakdown of a large molecule and buildup of another molecule. We're going to see exactly how that works. Um, and I've had some students ask me some questions like this in the past before. Um, and I've actually had a few YouTube commenters kind of wonder about this as well. Um, and I think it's important to discuss this because, you know, a lot of times AP biology is like, "All right, know this, know this, know this, know this, know this, know this, and then it'll be on the exam." But a lot of times some of the underlying base knowledge um is required for context and to gain a deeper understanding here. So, uh, I'm going to make this really, really simple here. Um, so one of my commenters and several of my students in my past were like, "All right, why are dehydration synthesis and hydrarolysis, those two reactions that we're going to be talking about today, the buildup of monomer or excuse me, buildup of monomers into polymers and the breakdown of polymers into monomers. Why is that even necessary?" Uh, well, all living things have to take in carbon based molecules from their environment. Aka, you have to eat food. Um, and then your food is used as well, it's used as fuel for energy, but it's also those building blocks from your food are used to make up the molecules in your cells that make up you. Okay, so uh let me let me pose it this way here. All right, let's say you have this nice delicious uh ham sandwich for lunch and then uh you eat that ham sandwich and let me put it this way. Do you become part ham sandwich? I mean, that poster in the lunchroom uh in your elementary school said, "You are what you eat." So, are you ham sandwich if you're going to eat that ham sandwich? And I would say no, not not exactly. But the molecular components of that ham sandwich, presuming that that the parts of that ham sandwich came from a living thing once, um the parts the molecular components of that ham sandwich are going to be rearranged to form the components that make up you. Okay? So, uh, think of it like a Lego set, right? You take, if you take apart a Lego set and you get, uh, get those individual bricks, you can rearrange those individual bricks to form something completely new. And that's what metabolism is. Um, and metabolism can be broken down broken down into two main groups here. The buildup of large molecules from smaller ones and the breakdown of large molecules into smaller ones. Um, and there's two types of reactions here that we're going to be talking about today. Um, but let's just clear this out of the way here first. And what I mean by a polymer is that it's a large molecule made of smaller subunits. All right? So I took these uh colored circles here. Um and these could be amino acids. These could be monossaccharides. These could be nucleotides maybe. Okay? But uh they're all it represents a molecule that's made up of a group of smaller other ones that's usually put into a chain type of shape. Um so a large molecule made of smaller subunits is a polymer. If I take all these little circles together and I link them up, um therefore I am making what's called a polymer. Poly means many. All right? And the opposite of a polymer is what's called a monomer. And it looks like my face is in front of the definition over there. Okay? But uh monomers are small subunits made of larger molecules. So if I take apart this polymer, I break the bonds between these uh individual components, I can get their individual subunits by themselves, which are what are called monomers. All right? And these are all separated out. There are no covealent bonds between them. Um so check it out. Here's a really really simple schematic of these uh two main groups of reactions here. All right, so let's just say you know this is a polymer that comes from your food. This polymer comes from your ham sandwich. Um and it is a large complex macroolelecule because it made it came from a living thing, right? But in order to use that, you can't just like take that polymer and then put it to use on your own. Maybe in some cases you can, but generally speaking, it's not really a thing. So it needs to be broken down into those small pieces first which are called which is called hydraysis. Okay. The breakdown of a polymer into monomers is called hydraysis. And we're going to be looking at that in a second here um in a little bit more detail. All right. And then if I want to take those poly or excuse me those monomers and put them back together and rearrange them in new ways that my cells can actually use and I can benefit from well then I need dehydration synthesis. And that's our other type of reaction that we're going to be looking at today. And hydrarolysis and dehydration synthesis are exact opposites of one another. Um and it's that's going to become very very clear here in just a moment. All right. So hydraysis is the type of biological reaction that breaks down large molecules into smaller ones. A very simple definition there. Okay. So if I take this large molecule, this polymer up here, I'm going to assume it's a polysaccharide, but we're going to talk about that in the next uh video. All right. And I want to break it down. All right. I can break down this polymer into what are called dimers through hydrarolysis. All right, die meaning two. Right, so here's two monomers. If I put them together, it's called a dimer. Polymer to DR. And then if I'm going to hydrayze it a little further, I can break down these DRS into monomers. All right, but going from polymers to monomers is what hydraysis is all about. All right, so let's take apart that word for a second. Hydraysis, hydro means water. Lis means break. Okay, so you're breaking with water. We'll see here in just a second. water molecules are added to the bonds between the monomers breaking the coalent bonds between them. Okay. So, here's my polymer. Very simple polymer up here. It's got uh three subunits here. Um and there's a covealent bond between them. All right. And what's going to happen here is that I'm going to have some water molecules. And this is done through the help of enzymes, which we'll talk about a lot in unit 3 um with done with the help of enzymes. But this uh this water molecule is going to be used to kind of attack this covealent bond over here. All right. And the water molecule, as we know from 1.1, is made up of two hydrogens's and one oxygen. Or we can say it's made up of what's called a hydroxal group, an O, and one extra hydrogen ion onto there. Okay? So that water molecule kind of gets split up, all right, into those two components. An O is by by the way called a hydroxal group. a hydroxal group gets attached to one monomer and a hydronal or a hydrogen ion um gets attached to the other monomer and therefore that covealent bond between those monomers no longer exists. Okay, and those monomers are going to uh bond to that O and that H instead therefore breaking the monomers apart from one another. Okay, so as I said here, just to reiterate, hydrogen ion from one water molecule um attaches to one from one water molecule is attaches to one monomer and the hydroxal group is attached to the other and therefore those monomers are no longer coalently bonded to one another. All right, the polar opposite of uh of hydraysis is what's called dehydration synthesis. Okay, where I'm going to take some monomers and then I'm going to form covealent bonds between them um in order to well I guess in this diagram first make some DRS and then put those together to make a polymer. All right. So again we are going from monomers to polymers those individual units into one larger macroolelecule. Um and we're going to join them with coalent bonds. Again let's take apart this word here dehydration. When you hear that word dehydration it means like yeah hydrate uh make sure you're hydrated. Um but uh and then synthesis means to build together. So dehydration, you're taking away a water molecule. All right? If you've ever heard of dehydrated fruit, right? You're taking away the water. Taking away water to build something. All right. How does that actually work? Well, we just saw it with hydraysis, except it's going to be the exact opposite here. All right. I'm going to animate that again here. Ready? Um here's my uh monomers from before. Here's the O's and the H that were um attached to each of these. And what's going to happen is that those that hydroxal group and that hydrogen ion that H and that O are going to be removed from those two monomers. It's going to be taken away. Um so that these new monomers can bind with each other or they're not new but those monomers can form new bonds with each other instead of with that H and that O. So dehydration means we're taking away that oxygen uh that O and that H to form a new covealent bond between those monomers and link them together um to form DRS or polymers. Okay. Um so as I put down here each monomer loses a water molecule and new coalent bonds to connect two monomers to one another. Um so we're forming those new coalent bonds and building them together. All right. If we take this at a larger scale, um we're doing something called polymerization. So dehydration synthesis of a lot of monomers um to form a very large polymer is what's called polymerization. And that's a fun word to say. Um but think about it for a second. We're going to talk about this when we get to proteins and nucleic acids, but a protein, some of the largest proteins are hundreds, even thousands, tens of thousands of amino acids long. And it's going to take, you know, 10,000 dehydration synthesis reactions um in order to build one protein. All right? On DNA, they're super duper long molecules made of monomers called nucleotides. You're going to have to take a whole lot of dehydration synthesis and take a whole bunch of water molecules, H's and OH's away in order to build those uh really really big molecules that we're going to be looking at later on. Okay, so just to recap here in case I missed anything and in case you need it just in plain writing in front of you, uh, living things require intake of carbon based molecules. These molecules must be broken down and rearranged to form molecules needed by cells. You need to eat food. What your food becomes is the molecules that h you're going to use. But how is that done? They need to be broken down first into monomers through hydraysis. Hey, those polymers need to be broken down first into those smaller building blocks that then can be rearranged and rebuilt into new polymers through what's called dehydration synthesis. Um, and how does that actually work? Hydraysis uses a water molecule to separate a coalent bond. Adds an H to one monomer and an O to the other, breaking the coalent bond between them. And then dehydration synthesis is the exact opposite. Take an O from one monomer and an H from the other monomer. Take them apart and uh I should say take the uh take the H and the O, put them together, form a new water molecule, make that coalent bond between those two monomers, and then you're going to end up with something that's not a monomer. It's going to be a dimer. Or if you take it a whole bunch of them, you're going to get a polymer. Um that is it for this video. Please let me know if you have any questions and we will see you next time for 1.4 and four on carbohydrates.