Glycerophospholipids - Video Tutorials & Practice Problems
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Glycerophospholipids
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In this video, we're going to begin our lesson on Glycerophospholipids. Now before we actually define Glycerophospholipids, it would be helpful to first define the more generalized class of just phospholipids, which you can actually see phospholipids is embedded in the word glycerophospholipids. And so phospholipids are, again, a generalized class of lipids. So they're going to be a large class of lipids that are going to include lots of different molecules. But as the name implies, phospholipids are literally just lipids themselves that contain at least 1 phosphate group and phospholipids are a major component of all cell membranes and later in our course, we're going to talk a lot more details about cell membranes. And so that's important to keep in mind. Phospholipids, a major component of all cell membranes. Now we know that phospholipids are fatty acid base lipids because phospholipids contain at least 1 fatty acid molecule that's going to be linked to, again, a phosph phosphorylated platform molecule. And so if we take a look at our image down below at our phospholipid over here, notice that we have a platform molecule here, and this is a phosphorylated platform molecule because you can see the phosphate group attached to the platform molecule. And again, you can tell that phospholipids are indeed fatty acid based because they have at least one fatty acid chain. And here we are showing 2 fatty acid chains, but really, they just need at least one fatty acid chain. And again, this platform molecule can be a different, can be different molecules. And so if the phosphorylated platform molecule is a glycerol molecule, then it would be considered a Glycerophospholipid. And so you can see that by changing the platform specifically to a glycerol molecule, like this one right here, then what we'll get is a Glycero phospholipid, which we'll talk a lot more details about in our next lesson video. But also notice that the platform molecule could be something else other than a glycerol molecule. It could be a different molecule that we're just going to label as platform number 2 for now until we get to this, later in our course. But keep in mind that we can get different phospholipids just by changing the platform molecule. And again, we're going to focus on the glycerol platform molecule here and talk about glycerophospholipids in our next video. So I'll see you guys there.
2
concept
Glycerophospholipids
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5m
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Video transcript
Alright. So in this video, we're going to focus specifically on Glycerophospholipids and if we take a look at our lipid map, we can better orient ourselves on where we are. And so we know that we're exploring the fatty acid based lipids first. And already in our previous lesson videos, we've covered Glycerolipids and the Triacylglycerols. And so in this video we're going to focus on another type of Glycerolipid, the Glycerophospholipids, which we already mentioned in our last lesson video are just a type of phospholipid that uses a glycerol molecule as the platform. However, we also know that there are other types of phospholipids that use other molecules as the platform such as platform number 2 over here, which we'll talk more about what that is later in our course. For now, we're gonna focus on the Glycerophospholipids. And so Glycerophospholipids actually have several different synonyms. They're commonly referred to as phosphoglycerides, and occasionally, you'll also see them referred to as phosphoacylglycerols, and so glycerophospholipids, phosphoglycerides, and phosphoacylglycerols are all practically synonyms of each other, but if you break down the roots of these words and compare them, you'll notice that all of them have a phospho prefix to indicate that they are phospholipids and they all have some kind of glycerol or glycera or, glycerol root to indicate that they are also glycerolipids and have a glycerol molecule. And so when you compare them in this way, it's pretty easy to see that they are synonyms of each other. Now when it comes down to it, glycerol lipids are defined as lipids with a glycerol 3 phosphate group. And they're going to be attached specifically to 2 fatty acid chains. And so if we take a look at our image down below here in this box, notice over here on the far left, we're zooming into a cell's membrane here. So we know that phospholipids are a major component of the cell membrane. And if we zoom in on one of these phospholipids here, we can take a closer look at the glycerophospholipid, which notice has a glycerol molecule as the platform, which is, a 3 carbon molecule. And, notice that, instead of having 3 fatty acid chains, it only has 2 fatty acid chains here. And the 3rd carbon, instead of being linked to another fatty acid chain like triacylglycerols, it's linked to a phosphate group. And so, because it has the glycerol and the Phosphate group, that's why we have the Glycerophospho prefix. And it's clear to see again that these are fatty acid based lipids, because they have the fatty acid chains. Now, one thing to note here is that this Phosphate group can actually be Phosphodiester linked to this X group over here that we're calling the variable head group. And so this x group is the variable head group, and so up above in our lesson, we're saying that a phosphodiester linkage can actually attach other variable head groups or x. And, this variable head group x can be many different groups and these groups are usually polar molecules. And so if you have a variable head group here that tends to be polar, then what you end up getting is a polar group up here and non polar groups down here with these hydrocarbon chains. And then that means that you're gonna end up having an amphipathic molecule. And so glycerophospholipids are amphipathic, and that is partially what makes them so suitable for biological membranes. And so, it turns out that, Glycerophospholipids are actually the major, phospholipid in the cell membranes. And so if you were to pick a phospholipid randomly from a cell membrane, the likelihood is that it's going to be a glycerophospholipid. So this is the classic, phospholipid if you will. And so, it turns out that by changing this variable head group, you can actually get different types of Glycerophospholipids. And so in our next lesson video, we're gonna be able to talk about some of those different types of Glycerophospholipids and those different variable head groups. So I'll see you guys in that video.
3
concept
Glycerophospholipids
Video duration:
6m
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Video transcript
Alright. So in this video, we're going to talk about the classes of Glycerophospholipids. And so as we mentioned in our last lesson video, Glycerophospholipids are actually classified based on the variable head group that they have. And so down below, notice what we have is the same glycerophospholipid structure from our last lesson video. And notice that the variable head group is represented as x here in our structure, and so just by simply changing what this variable head group is, you can change the class of glycerophospholipid. And so really it's all about this variable head group. And these different variable head groups not only do they dictate the structure and the class of the glycerophospholipid but they also are going to dictate the function of the Glycerophospholipid and so we're not going to get into all the details of all of the different functions that these classes of Glycerophospholipids have, but as we move along through our course, we are going to talk about some of their functions. Now another important thing to note is that within each class of Glycerophospholipid, the fatty acid chain length and degree of saturation can actually vary, between molecules of each class. And so, again, these fatty acid chains that are attached, they can vary in their length or the number of carbon atoms, and they can vary in their degree of saturation, creating different molecules, within each class that you see down below. Now one thing to note is that the actual classes of Glycerophospholipids that you're going to need to know is going to depend on your professor and so, it's possible that maybe you guys don't need to know any of these Glycerophospholipid classes. But if you do need to know any classes of glycerophospholipids, the chances are that there, the ones that you need to know are in this table that you see down below. And so notice that in this table down glycerophospholipid class in the first column and then the variable head group that, defines that glycerophospholipid class. And so one thing that's important to note is that if there is no variable head group here and the phosphate group here is actually deprotonated with a negative charge, then this molecule is going to be a Glycerophospholipid called a Phosphatidate and that's the first class that we have in our table down below. And so the phosphatidate, you could pretty much think of it as the simplest glycerophospholipid because it doesn't actually have a variable head group. It's literally going to be found in the deprotonated form with, again, a negative charge on the phosphate group. And so you can think of phosphatidate as being pretty much like the backbone for all of the other glycerophospholipid classes. And so whenever you have a variable head group branching off of a backbone, the suffix y l, you might recall from your organic chemistry courses, is used to indicate things that are branching off. And so, one of the things that you'll note is that a lot of these classes down below have this phosphatidate type of prefix, but then they also include the yl in there to indicate the branching off of that backbone. And so, you'll notice that you'll see this phosphatidyl, prefix in so many different classes here of this of these, Glycerophospholipid classes, you'll see this phosphatidyl prefix. And so notice that in our map here, when we zoom in on glycerophospholipids, notice that branching off of it, we have phosphatidates, which again, we said is the simplest class of, glycerophospholipids because they don't have a variable head group. They are completely deprotonated. And so again, if you, add the y l prefix to, the phosphatidate, then you can branch off all of these different variable head groups that you see down below. And these variable head groups that you see here create all of the classes that you see, down below, the glycerophospholipid classes. And so, again, the exact Glycerophospholipid classes that you guys are responsible for knowing is gonna depend on your professor. And so make sure to double check with your about which ones you should know specifically but notice that we do have a star here right next to phosphatidylcholine, and the reason that we have this star here next to phosphatidylcholine is because this class of glycerophospholipid is actually the one that is most common in all cell membranes. And so this is pretty much the prototype. This is the one that is most abundant in cell membranes. And so you can see that we've color coded the green, words here to show exactly, what, the variable head group will be. And so in phosphatidylcholine, the variable head group is choline, which is this molecule that you see right here. And so, some of these, variable head groups you should actually recognize such as serine. This is literally the amino acid serine branching off. Glycerol literally has a glycerol molecule branching off. And, again, some of these, we have not yet talked about, but, again, it's going to depend on your professors, which ones you're specifically going to need to know. But these are the most common classes of Glycerophospholipids. And again, we'll be able to get some practice applying the concepts that we've learned here, in our next couple of videos. So I'll see you guys there.
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Problem
Problem
A certain glycerophospholipid is made of glycerol, two fatty acids, and ethanolamine. What components does the carboxylic ester linkage connect?
a) Phosphate and ethanolamine.
b) Glycerol and fatty acids.
c) Fatty acids and phosphate.
d) Glycerol and ethanolamine.
e) There are no ester linkages is the glycerophospholipid.
A
Phosphate and ethanolamine.
B
Glycerol and fatty acids.
C
Fatty acids and phosphate.
D
Glycerol and ethanolamine.
E
There are no ester linkages is the glycerophospholipid.
5
Problem
Problem
Phosphatidate is a glycerophospholipid formed from:
a) Glycerol-3-phosphate and two fatty acid chains.
b) Glycerol-3-phosphate and two free fatty acids.
c) Glycerol and two fatty acid chains.
d) Pyruvate and triacylglycerol.
A
Glycerol-3-phosphate and two fatty acid chains.
B
Glycerol-3-phosphate and two free fatty acids.
C
Glycerol and two fatty acid chains.
D
Pyruvate and triacylglycerol.
6
Problem
Problem
Which of the following is not a common headgroup of glycerophospholipids?
a) Ethanolamine.
b) Choline.
c) Serine.
d) Hydrogen atom
e) Threonine.
A
Ethanolamine.
B
Choline.
C
Serine.
D
Threonine.
E
Hydrogen Atom.
7
Problem
Problem
Which of the following is a major component of a cell's plasma membrane?
a) Triglyceride.
b) Phosphatidylcholine.
c) Waxes.
d) Eicosanoids.
e) Lipid Vitamins.
A
Triglyceride.
B
Phosphatidylcholine.
C
Waxes.
D
Eicosanoids.
E
Lipid Vitamins.
8
Problem
Problem
What is the name of the glycerophospholipid shown below?