Sphingophospholipids - Online Tutor, Practice Problems & Exam Prep

Sphingophospholipids, particularly sphingomyelin, are crucial components of cell membranes. Sphingomyelin features a sphingosine backbone linked to a phosphate group, with variable head groups like phosphocholine or phosphoethanolamine. This amphipathic structure allows it to form lipid bilayers, essential for the myelin sheath surrounding nerve cell axons, facilitating rapid nerve signal propagation. Understanding sphingomyelin's role highlights its significance as the most common sphingolipid in the nervous system.

Sphingophospholipids

In this video, we're going to begin our introduction to sphingophospholipids. Now before we get started, let's first take a look at our lipid map to make sure that we're all on the same page about where we are. And so, of course, we know that we're currently exploring all of the fatty acid based lipids, and we've already explored the glycerolipids, and we're currently in the process of exploring the sphingolipids. And so here in this video, we're specifically talking about the sphingophospholipids. And so you'll notice that this is taking the place of what used to be platform number 2 in some of the other versions of our map, and that's because this is a phospholipid that uses platform number 2, and platform number 2 is the sphingosine molecule. And so, really, when we take a look at phospholipids as a whole, we can see that the template of a phospholipid is just a platform that is phosphorylated and contains at least one fatty acid chain.

Now if we change the platform specifically to a glycerol molecule, we'll get the glycerophospholipids that we already covered in our previous lesson videos. But if we make the platform a sphingosine molecule instead of a glycerol molecule, we'll get the sphingophospholipid and so really that is what we're introducing here in this lesson. And so again, the sphingophospholipid is just going to be a sphingolipid that's covalently attached to a phosphate group. And it's as simple as that. And so the most common sphingophospholipid is actually the molecule sphingomyelin, which we're actually going to introduce in our next lesson video. So, I'll see you guys there.

Sphingophospholipids

In this video, we're going to introduce a very specific sphingophospholipid, which is sphingomyelin. And not only is sphingomyelin the most common sphingophospholipid, it's also the most common sphingolipid, so that's definitely noteworthy. Now, sphingomyelin is again a Sphingophospholipid, which of course means that it's going to have a sphingosine backbone and it's going to be attached to a phosphate group. And it turns out that the variable head groups are either going to be phosphocholine or phosphoethanolamine head group. Now down below in the image of our sphingomyelin, notice that you can see that there definitely is a sphingosine backbone here, so that's the sphingo part, and then also notice that there is a phosphate group here, so that's the phospho part, and so that's what makes sphingomyelin a sphingophospholipid, as we mentioned. And what you'll also note is that we're showing you here that the variable head group is phosphocholine. And, again it could also be phosphoethanolamine, and we showed you what an ethanolamine group looks like in the Glycerophospholipid classes table from our previous lesson video. So you can go back and check that out if you're interested. But really the main takeaway here is that we've got a phosphate group that's going to be included and this is going to be a polar headgroup. So, because it has a polar head group and then it has these nonpolar tails down here, this is what makes sphingomyelin an amphipathic molecule and makes it so suitable for membranes. And again, it's the most common sphingolipid. And the reason for that is because as the name implies with the myelin here, sphingomyelin is the primary structural component of the membranous myelin sheath. And so, you might recall from your previous biology courses or human anatomy and physiology courses that the myelin sheath is a membranous structure that surrounds the nerve cell axons of our nervous systems. And so notice over here, we're showing you an image of the axon of one of our nerve cells from our nervous system. And you'll note that it's being surrounded by this membranous structure here that's called the myelin sheath. The myelin sheath really helps for nerve signals to be propagated down the axon much faster. But really the main takeaway here is that this myelin sheath is made up mainly of sphingomyelin, as the name implies, it's found in the myelin sheath. And so because sphingomyelin is such a major structural component of the myelin sheath and the myelin sheath is found so prevalently throughout our nervous systems, that is what makes sphingomyelin the most common sphingolipid. But again, the major takeaway here is that sphingomyelin is a sphingophospholipid, and it's going to be found in the myelin sheath as the most common sphingolipid. And so, this here concludes our lesson on sphingomyelin, and we'll be able to get some practice applying the concepts that we've learned in our next few videos. So, I'll see you guys there.

Label the following as relating to (A) sphingophospholipids, (B) glycerophospholipids, or (C) triacylglycerols. 

A) Contains two variable fatty acids: ______                      

B) Does not contain a phosphate group: ______                

C) Contains an amide linkage: ______                                 

D) Commonly utilized for obtaining energy: ______

E) Formed from glycerol and three fatty acids: ______

F) Has a sphingosine backbone: ______

Alright. So this practice problem wants us to label the following down below as either relating to, a, sphingophospholipids, b, glycerophospholipids or c, triacylglycerols. And part a says, contains 2 variable fatty acids. Now, the tri in triacylglycerols reminds us that it's going to have 3 variable fatty acids not 2. Sphingophospholipids or sphingolipids in general, they're only going to have one variable fatty acid not 2 and that's because the other fatty acid that it contains is going to be constant and not variable. And so the only one that contains 2 variable fatty acids is going to be b glycerophospholipids. So we can go ahead and put b here for this option. Now, moving on to part b, it says, does not contain a phosphate group and of course, sphingophospholipids and glycerophospholipids are both going to contain phosphate groups because of the phospho prefix. And so the only one that does not contain a phosphate group is going to be the triacylglycerol. So we can go ahead and put c here to indicate that is the answer for this part. So now moving on to part c, it says, contains an amide linkage. And you might recall from our previous lesson videos that amides are present in sphingolipids. And so sphingophospholipids are also going to contain amides. And so the correct answer for part c is going to be a for sphingophospholipids. Glycerophospholipids don't contain amide linkages, they contain ester linkages for the most part, and triacylglycerols also contain ester linkages. So now moving on to part d, it says commonly utilized for obtaining energy. And of course, we know from our previous lesson videos that triacylglycerols function as long term energy storage molecules. And so really that is going to be the function of, triacylglycerol. So we'll put c here for that. Moving on to option e, it says, formed from glycerol and 3 fatty acids. And again, the tri part in triacylglycerol reminds us that there are 3 variable fatty acids, and so again, this is going to apply to c. And then last but not least, it says, has a sphingosine backbone, and, of course, the glycerol and, the glycerol here indicate that they have glycerol backbones. And it's the sphingo here that indicates that it has a sphingosine backbone. So it's actually option a, that is the correct answer for this last part. And so that concludes this practice problem and I'll see you guys in our next video.

Here’s what students ask on this topic:

What are sphingophospholipids and how do they differ from glycerophospholipids?

Sphingophospholipids are a type of phospholipid that have a sphingosine backbone instead of a glycerol backbone. The most common sphingophospholipid is sphingomyelin. In contrast, glycerophospholipids have a glycerol backbone. Both types of phospholipids contain a phosphate group and at least one fatty acid chain, making them amphipathic and suitable for forming lipid bilayers in cell membranes. The key difference lies in the backbone structure: sphingophospholipids use sphingosine, while glycerophospholipids use glycerol.

What is the role of sphingomyelin in the nervous system?

Sphingomyelin plays a crucial role in the nervous system as the primary structural component of the myelin sheath. The myelin sheath is a membranous structure that surrounds nerve cell axons, facilitating rapid propagation of nerve signals. This amphipathic molecule, with its polar head group and non-polar tails, forms lipid bilayers essential for the integrity and function of the myelin sheath. The presence of sphingomyelin in the myelin sheath ensures efficient nerve signal transmission, making it the most common sphingolipid in the nervous system.

What are the variable head groups in sphingomyelin?

The variable head groups in sphingomyelin are either phosphocholine or phosphoethanolamine. These head groups are attached to the phosphate group in the sphingosine backbone, contributing to the molecule's amphipathic nature. The presence of these polar head groups, along with the non-polar fatty acid tails, allows sphingomyelin to form lipid bilayers, which are essential for cell membrane structure and function, particularly in the myelin sheath of nerve cells.

Why is sphingomyelin considered an amphipathic molecule?

Sphingomyelin is considered an amphipathic molecule because it contains both hydrophilic (polar) and hydrophobic (non-polar) regions. The hydrophilic part is the phosphate group attached to a variable head group (either phosphocholine or phosphoethanolamine), while the hydrophobic part consists of the fatty acid chains attached to the sphingosine backbone. This dual nature allows sphingomyelin to form lipid bilayers, making it essential for cell membrane structure and function, particularly in the myelin sheath of nerve cells.

How does the structure of sphingomyelin contribute to its function in cell membranes?

The structure of sphingomyelin, with its sphingosine backbone, phosphate group, and variable head groups (phosphocholine or phosphoethanolamine), makes it amphipathic. This means it has both hydrophilic and hydrophobic regions, allowing it to form stable lipid bilayers in cell membranes. The polar head group interacts with the aqueous environment, while the non-polar fatty acid tails interact with each other, creating a barrier that is essential for cell membrane integrity and function. This structure is particularly important in the myelin sheath, where it facilitates rapid nerve signal transmission.