Lipids

switching gears a little. Let's look at some questions related to lipids. If you haven't answered questions 16 yet pause the video here. So which of the following is true about sterols? The answer is that all sterols share if used ring structure which actually includes four rings, I'll draw it out for you. Right now it is made up of three six members rings and one five members bring and that is a sterile or, I should say, the backbone of a sterile molecule. Um, now, the other question or the other statements here are obviously false. So sterols sterols air not on Lee found in the membranes of living cells. Um, they could be found in the membranes of dead cells. Just kidding. They can be found many, many other places. They're used as hormones, so they have a wide variety of uses in the body they found all over the place. They're not soluble in water. I mean, look at that structure that is screaming hydrophobic. It does have this Ohh. So it can form a church funds and actually, when it is embedded in the membrane, you know you'll have sort of the surface of the membrane there, Um, this being the inside in this the outside. So this this can interact with water. This obviously can't. Cholesterol is actually the main sterile and humans, whereas ergo, sterile is the main sterile in fun guy. So this is completely backwards. Basically, yeah, ergo, sterile in fungi, cholesterol in humans. Now the fluidity of the membrane is generally increased by increasing the number of double bonds in fatty acids. And if you remember, increasing the number of double bonds and fatty acid will actually lower its melting point significantly. And additionally, all of these other statements are false, so let's go through them. Uh, increasing temperature will increase the fluidity, decreasing temperature decreases, fluidity. And that's why theknot com position of fatty acids in the membrane of an organism really depends on where it lives. If it lives in colder climates, it's going to want mawr unsaturated fatty acids because they'll stay more fluid at lower temperatures. If it lives in a warmer climate, it's going to want mawr unsaturated fatty acids because those will remain more rigid at higher temperatures. When you know if there were more unsaturated fatty acids and high temperatures, they would become too fluid in the membrane would fall apart more or less binding of water to fatty Aysal side chains. Good luck with that water. And those fatty Estelle side chains want nothing to do with each other, and an increase in the percentage of foster title ethanol Amine is actually the opposite of the case. If you, uh, phosphate title Ethanol Amine actually decreases fluidity. Not by a huge amount, but it does a little bit. And actually Foss for title Coleene increases fluidity. All right, Looking at Question 18 singles scene is not a component of cardio lie pin. Spin magazine is an essential component of single lipids. It's pretty much where they get their name from, and it's more or less what they're using in place of glycerol, Um, and also fatty acid. You know, if you think of fossil lipids is having glycerol into fatty acids, spindle lipids will sometimes have that fatty acid, Uh, but they or rather, they don't. They won't have to fatty acids. That is to say, they'll only possibly have won. This finger zine molecule sort of replaces the glycerol and the fatty acid, or one of the fatty acids side chains cardio lie pin is actually a really kind of strange molecule, and it's found in in muscles and sorry mitochondrial membranes and in bacterial membranes, so mitochondrial and bacterial membranes. It's kind of strange looking molecule. If you wanna look it up, the rest of these are single lipids, so they will have swing a zine. Let's take a look at Question 19 now. Fatty acids are components of Serie besides, which again are spindle lipids? So they're going thio have a spin magazine molecule attached to you, a fatty acid and also some sort of head group and carry teens thes air ice, Supremes and these guys. Oh, sterols. All right, moving on. Which of the following statements concerning fatty acids is correct, and the answer is that a fatty acid is the precursor of prostaglandins, and that fatty acid is Iraq and Iraq. Adan IQ acid and this is what's known as Andi Coast, annoyed and, um, just looking at the wrong answer choices. Phosphate. I tick acid is a common fatty acid. No, it's not a fatty acid. Fatty acids all contain one or more double bonds. No, some are unsaturated our summer saturated right, so this is wrong because there are some saturated fatty acids. Fatty acids are constituent of sterols. No, they're not. Sterols air. Those four few met a Those four fused rings. Fatty acids are strongly hydro Filic. No way. Super hydrophobic, right? All right, so let's finish it up here and diagram this molecule. I'm just going to do it in a skeletal structure to keep it nice and simple. So I'm actually gonna start by drawing my Esther's just to kind of give shape to the rest of my molecule. All right, so there are my Esther's. Uh, this is my glycerol, and here is my phosphate group. And again, I apologize. But this is not the prettiest picture in the world. So here we have coleene. This is, of course, our phosphate right here. Um, glycerol is our backbone right there. And let's do our fatty acids now, so we know that it has this fatty acid which we can see contains one double bond at carbon nine. And it has this fatty acid which is completely saturated. It doesn't tell us which one goes where, but we should know that if there is one on Lee one unsaturated fatty acid. That's going to appear at position two on the glycerol. Right. So here's position 12 and this is We have three there. It's I know my drawings, like, super, super horrible. I'm sorry. Um, this is not the important part. You know, The important part is understanding our fatty acid naming convention here. So let's start with dot econo ic acid. It's gonna have 12 carbons and again, zero double bonds. That's what those numbers mean. So 123456789 10 12 There were done. Now, Paul metallic acid. This is gonna have 16 carbons, one double bond. And that double bond is going to be between carbon nine and 10. So Double bond. 10 11 12 13 14 16. And there we go. That is our molecular structure. I'm sorry. It's such a hideous picture. And let's try to forget about it as we turn the page