tinywow_video_to_text_65330668.txt

So, now we're going to talk about carbohydrates as a class of macromolecule here. And we'll start with talking about carbohydrate, where it gets its name. It turns out, so a typical carbohydrate is going to have the form of the C-N-H-2-O-N as well. So, for every carbon, there's the equivalent of a w...

So, now we're going to talk about carbohydrates as a class of macromolecule here. And we'll start with talking about carbohydrate, where it gets its name. It turns out, so a typical carbohydrate is going to have the form of the C-N-H-2-O-N as well. So, for every carbon, there's the equivalent of a water molecule, at least in the formula. It turns out they don't actually exist as like separate water molecules or anything like that. So, you're typically going to find these carbohydrates having lots of OH groups, poly alcohols, in most examples and things of the sort. And we'll talk about the monor first, those are called monosaccharides. You'll find out that they can actually still, as monomers, still carry out a function of living creatures. You know, oftentimes glucose, monosaccharide, is something inside ourselves we use as fuel. So, it actually has a purpose. So, disaccharides as well, we'll find out like sucrose here. So, sugar in like sugar cane, blue plant sugar is a combination of glucose and fructose bonded together. So, disaccharides. And then we'll talk about polysaccharides as well, where you can get big polymers and big chains with dozens or hundreds or even thousands of monosaccharides together. Now, the one I include in here is called oligosaccharides. In fact, I'll write that out real quick. So, in oligosaccharides, usually if you've got, you know, more than two, but less than twelve, that's probably an oligosaccharide. So, and then more than twelve is probably considered polysaccharide, but most you probably aren't going to see this term. So, I didn't really throw it in there. But just on the odd chance you see that term oligosaccharide, it's a short chain of monosaccharides together. Okay. So, let's talk a little more about these monosaccharides, the basic subunit here. And it turns out these monosaccharides exist in one of the couple different forms. There's an open chain form, but there's also cyclic form. So, we'll find out that these are typically equilibrium with each other, but we'll find out that the cyclic forms often predominate equilibrium, both in the test tube, as well as in biological organisms. All right. So, if you notice, most of the carbons have an alcohol, OH there, OH there, OH there, OH there, OH there, and in here in deglucose, there's one carbon that doesn't have an OH in the open chain form, and that's a carbonyl, and that's how most monosaccharides exist. They're a carbonyl in one location, if that is at the terminus, that's an aldehyde, and we call an aldehyde monosaccharide and aldose. So, if the carbonyl carbon is not at the terminus, but somewhere in the interior, like with the D-fruit-nose here, then we'll call that a ketose, being that it has a ketone as part of it. So, every other carbon has an OH group, an alcohol group. So, these are poly alcohols, except at one carbon, they're going to be either a ketone or an aldehyde, therefore, either being a ketose or an aldose. All right. If you kind of look at how we get from the open chain to one of these cyclic forms, you're actually going to have a cyclization that's going to take place here. So, when you're having, you have a nucleophilic attack here, so from one of the oxygens coming and doing nucleophilic attack here, so what you're going to have, this oxygen is eventually going to get protonated, become an OH, it's one in blue over here in the open chain forms, and then one of the oxygen is the one I've got diagrammed in here, in red, is now going to be bonded between two of the carbons forming a ring. So, in this case, you've got five carbons and an oxygen in the ring. If we actually number this, in fact, let's make this a little bigger here, let's number the chain. We've got carbon one, two, three, four, five, and six, and here we've got carbon one, two, three, four, five, and six, and so here, the oxygen on carbon five, so it's now also bonded to carbon number one, and then carbon number one, that used to be a carbonyl, now has an alcohol group. Again, that blue oxygen there got protonated, and it's now, and I say it's an alcohol, it's an OH, it's a hydroxyl group, but it's actually not an alcohol. This is a particular fungal group that we call a heme acetyl, acetyl, and I said acetyl and ketyl, it should have said heme acetyl and heme ketyl. So, if the cyclic form is forming from an aldo sugar, it'll actually form a heme acetyl, and you can recognize that heme acetyl because you're going to have a carb in here that is bonded as two oxygen atoms. One of them is an OH, and one of them is not an OH, it's an OR, in this case an O bonded to another carbon chain. Cool, and again, that's your evidence you've got a heme acetyl, now in the case of our ketose over here with fructose, so you can see the same thing, and it turns out with fructose, you can form a six member ring if you use the oxygen down here, and it turns out in the case of what happens, but in bilateral organism, it turns out it normally forms a five member ring, it's one of these five member rings that is the most common form in living creatures, but again, you're still going to have an equilibrium where all of these are possible and exist together, so it turns out the cyclic forms predominate in vivo. In this case, again, if we numbered the chain, we'd have carbon one, two, notice that carbon heal is not the end of the chain, it's not carbon number one in this case, it's number two. So, three, four, five, and six, same thing over here, carbon one, two, three, four, five, and six. And once again, you can recognize now that you've got a hemiketal, because you've got a carbon here that's bonded with two options, one of them is an OH and one of them is not, it's an O with a carbon chain, an OR if you will, and that's your hemiketal. Cool, so the cyclic forms here, either hemiketals or hemiketals, be aware that a lot of people just use the term hemiketal ubiquitously to mean either hemiketal or hemiketal, but technically, if you're talking to an organic chemist, they'd be like, no, no, hemiketals are from aldosis, hemiketals are from ketosis. All right, so we talked about the monosaccharides, we next want to talk about disaccharides, and disaccharides are commonly present physiologically, and so they've got some relevance here. Here I've got sucrose, lactose, and maltose, both composed of two monosaccharides, and if you notice for all three of these, probably worth noting which two monosaccharides each of these is composed of, but notice one out of the two for all three is glucose. So glucose, most common monosaccharide you're ever going to see, so it might be worth memorizing its structure from the last slide, truth be told, but definitely the most common one you're going to encounter, and every major disaccharide you're going to have to memorize has glucose as one of the two, or at least one of the two. In the case of sucrose, which again is your table sugar, from sugar cane, it's glucose bonded to fructose, and lactose, it's glucose bonded to galactose, which makes these remember, it weighs lactose glucose bonded to galactose. And then finally maltose here is glucose bonded to another glucose, and it turns out the bond that is going to form between each of these there and there, and there, that is called a glycosidic bond, or glycosidic linkage, and the atoms that it's bonded to, and it turns out its chirality is going to play a role on how we designate it and stuff like that. I don't want to get too far into that. So if you look at this one right here on glucose over here, we're bonded at carbon number one, but on fructose it's at carbon one, two, three, four, and five, and it's carbon number five, and so it's actually got a one, five glycosidic linkage, it might be how we look at that. It turns out what I've identified as alpha or beta and stuff like that, but that's a little further than I think we need to go, and so, but you should know that the bond between monosaccharide monomers, whether it's in a disaccharide or oligosaccharide polysaccharide, they're called glycosidic linkages. So now we'll talk about polysaccharides here, and we'll start with starch, and it turns out starch is composed of two very similar glucose polymers, so it's just all glucose. In this case, we've got amylose, which is a linear polymer, so it only branches at the same two locations on every glucose, and if it's only branching in two locations, then each glucose is going to bond in two directions, that's why it ends up being a linear glucose polymer for amylose. So amylopectin has a very similar structure, except some, very few of the glucose monomers end up bonding in three directions here, like this one right here, so, and again, it has some of the same branches as amylose that ends up having a one-six glycosidic bond, not just one-four, so it can branch in three directions, and it largely only does that in a handful of locations, but this amylopectin ends up with a branched structure as a result. You should know that starch is made up of both amylose and amylopectin, you should know that amylose is linear, whereas amylopectin is branched. Other notable polysaccharides talk about, so glycogen, so glycogen is your main source of glucose storage for fuel, so both in your muscles as well as in your liver and in your muscles will learn that they're storing it for themselves, but your liver is not storing glycogen for itself, it's storing it for the rest of your body, so when you get low blood sugar and in normal conditions, your brain operates almost exclusively on glucose, so where a lot of other parts of your body might be able to function pretty quickly on other things, your brain like any glucose, any glucose, any glucose until you've been starving for a few days, it won't switch to using any other fuel source. Well, if you don't eat, then where are you going to get more glucose for your blood strip? Well, that's where your liver comes in, your liver stores up glycogen, it's a big glucose polymer, and if you haven't eaten in a while, it'll start chopping off the glucose monomers and releasing them in the blood stream to keep your blood sugar up. So glycogen is a glucose polymer, it's all glucose monosaccharides, so it turns out they have a lot of the same glycosidic bonds we saw in amylopectin and stuff like this back with part of starch, things of the source, cellulose, so cellulose probably the most abundant polysaccharide on planet Earth, so in fact, I see probably it is the most abundant, it's in the cell walls of plants, so plants pretty come, and so in this case, it turns out it's got a slightly different glycosidic bond, instead of being an alpha one four, it's a beta one four, and so it turns out it's still bond between carbons one and four of each monosaccharide, but the chyralides different, so well notice you can't actually digest cellulose, and the reason is that you have enzymes that'll break up the opposite chyral form of a one four linkage, but you don't have the ones that'll break apart the beta one four linkage, only the alpha one four linkage, so as a result, you can't digest cellulose, and so when you eat something that has a cell wall, like corn, let's say there's part of that coin, it's just gonna pass right through you, we call it fiber, in that case, it has some benefit, but the idea is that you can't digest it, if you can't digest it, it's not getting absorbed in, it's gonna pass right through you. Cool, other notable polysaccharide here is Titan, Titan is a linear polymer of a glucose derivative, it's not actually glucose itself but it's an acetyl glucose amine, often symbolizes nag or regated nag, also beta one four linkages, and again, it's glucose that's got an amine group essentially on it, and big thing to know about chyten is a structural element both in fungal cell walls but also in the exoskeletons of insects and arthropods like crabs and lobster.