Glycerophospholipids - Online Tutor, Practice Problems & Exam Prep

Glycerophospholipids, a type of phospholipid, are essential components of cell membranes, characterized by a glycerol backbone linked to two fatty acid chains and a phosphate group. The variable head group attached to the phosphate determines the specific class and function of the glycerophospholipid, making them amphipathic molecules suitable for biological membranes. The most common class, phosphatidylcholine, plays a crucial role in membrane structure. Variations in fatty acid chain length and saturation further diversify their functions, highlighting their importance in cellular processes.

Glycerophospholipids

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, as you can see, is embedded in the word glycerophospholipids. Phospholipids are a generalized class of lipids. They are a large class of lipids that include lots of different molecules. As the name implies, phospholipids are literally just lipids that contain at least one phosphate group. Phospholipids are a major component of all cell membranes. Later in our course, we're going to talk a lot more about cell membranes. It's important to keep in mind that phospholipids are a major component of all cell membranes.

We know that phospholipids are fatty acid-based lipids because they contain at least one fatty acid molecule that is linked to a phosphorylated platform molecule. 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. You can tell that phospholipids are indeed fatty acid-based because they have at least one fatty acid chain. Here we are showing two fatty acid chains, but really, they just need at least one fatty acid chain. This platform molecule can be different molecules. If the phosphorylated platform molecule is a glycerol molecule, then it would be considered a Glycerophospholipid.

You can see that by changing the platform specifically to a glycerol molecule, like this one right here, what we'll get is a Glycerophospholipid, which we'll talk a lot more 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. 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.

Glycerophospholipids

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.

Glycerophospholipids

Alright. So in this video, we're going to talk about the classes of Glycerophospholipids. As we mentioned in our last lesson video, Glycerophospholipids are actually classified based on the variable head group that they have.

Notice what we have is the same glycerophospholipid structure from our last lesson video. The variable head group is represented as x here in our structure, and by simply changing what this variable head group is, you can change the class of glycerophospholipid. It's all about this variable head group. These different variable head groups not only dictate the structure and the class of the glycerophospholipid but also dictate the function of the Glycerophospholipid. We're not going to get into all the details of all the different functions these classes of Glycerophospholipids have, but as we move along through our course, we are going to discuss some of their functions.

Another important thing to note is that within each class of Glycerophospholipid, the fatty acid chain length and degree of saturation can vary between molecules of each class. These fatty acid chains attached 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 you see down below.

One thing to note is that the actual classes of Glycerophospholipids that you're going to need to know will depend on your professor, and it's possible that you might not need to know any of these Glycerophospholipid classes. However, if you do need to know any classes of glycerophospholipids, the chances are that the ones you need to know are in the table down below. In this table, you see the glycerophospholipid class in the first column and then the variable head group that defines that glycerophospholipid class.

If there is no variable head group, and the phosphate group is actually deprotonated with a negative charge, then this molecule is going to be a Glycerophospholipid called a Phosphatidate, which is the first class we have in our table down below. Phosphatidate could be thought of as the simplest glycerophospholipid because it doesn't actually have a variable head group. It's found in its deprotonated form with a negative charge on the phosphate group. You can think of phosphatidate as being like the backbone for all of the other glycerophospholipid classes.

Whenever you have a variable head group branching off of a backbone, the suffix 'yl' is used to indicate things that are branching off. You'll notice that you'll see this phosphatidyl prefix in many different classes of these Glycerophospholipid classes.

Notice that branching off of it, we have phosphatidates, which, as said, is the simplest class of Glycerophospholipids because they don't have a variable head group. They are completely deprotonated. Adding the 'yl' prefix allows you to branch off all of the different variable head groups that you see down below. These variable head groups create all of the classes that you see in the glycerophospholipid classes.

The exact Glycerophospholipid classes that you are responsible for knowing will depend on your professor. Make sure to double-check with your professor about which ones you should know specifically. Notice that we have a star here next to phosphatidylcholine, which is because this class of glycerophospholipid is the most common in all cell membranes, making it the prototype and most abundant in cell membranes. The variable head group in phosphatidylcholine is choline.

Some of these variable head groups like serine, which is literally the amino acid serine branching off, glycerol, which has a glycerol molecule branching off, and others have not yet been discussed. It will depend on your professors, which ones you are specifically going to need to know. These are the most common classes of Glycerophospholipids.

We'll be able to get some practice applying the concepts that we've learned here in our next couple of videos. I'll see you there.

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.

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.

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.

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.

What is the name of the glycerophospholipid shown below?

• A. Phosphatidylglycerol.
• B. Phosphatidylethanolamine.
• C. Phosphatidate.
• D. Phosphatidylserine.
• E. Phosphatidic Acid.

Here’s what students ask on this topic:

What are glycerophospholipids and why are they important in cell membranes?

Glycerophospholipids are a type of phospholipid characterized by a glycerol backbone linked to two fatty acid chains and a phosphate group. They are essential components of cell membranes due to their amphipathic nature, meaning they have both hydrophobic (fatty acid chains) and hydrophilic (phosphate group) regions. This dual characteristic allows them to form the bilayer structure of cell membranes, providing a barrier that separates the cell's interior from its external environment. The variable head group attached to the phosphate determines the specific class and function of the glycerophospholipid, further diversifying their roles in cellular processes.

What is the difference between glycerophospholipids and other phospholipids?

The primary difference between glycerophospholipids and other phospholipids lies in the platform molecule. Glycerophospholipids use a glycerol molecule as the backbone, whereas other phospholipids may use different molecules as their platform. For example, sphingolipids use a sphingosine backbone. Glycerophospholipids are characterized by a glycerol backbone linked to two fatty acid chains and a phosphate group, making them a major component of cell membranes. The specific class and function of glycerophospholipids are determined by the variable head group attached to the phosphate.

What are the different classes of glycerophospholipids?

Glycerophospholipids are classified based on their variable head groups. Some common classes include phosphatidylcholine (with a choline head group), phosphatidylethanolamine (with an ethanolamine head group), phosphatidylserine (with a serine head group), and phosphatidylinositol (with an inositol head group). The simplest class is phosphatidate, which lacks a variable head group and has a deprotonated phosphate group. These classes differ in their structure and function, contributing to the diverse roles of glycerophospholipids in cellular processes.

How do glycerophospholipids contribute to the amphipathic nature of cell membranes?

Glycerophospholipids contribute to the amphipathic nature of cell membranes due to their molecular structure. They have a glycerol backbone linked to two hydrophobic fatty acid chains and a hydrophilic phosphate group. The hydrophobic tails face inward, away from water, while the hydrophilic heads face outward, interacting with the aqueous environment. This arrangement forms a bilayer, creating a stable barrier that separates the cell's interior from its external environment, essential for maintaining cellular integrity and function.

What role does phosphatidylcholine play in cell membranes?

Phosphatidylcholine is the most common class of glycerophospholipids in cell membranes. It plays a crucial role in maintaining membrane structure and fluidity. The choline head group is polar, contributing to the hydrophilic surface of the membrane, while the fatty acid tails are hydrophobic, forming the membrane's interior. This amphipathic nature allows phosphatidylcholine to form a bilayer, providing a barrier that regulates the movement of substances in and out of the cell. Additionally, it is involved in signaling pathways and membrane dynamics.