Sphingolipid Recap - Video Tutorials & Practice Problems
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Sphingolipid Recap
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In this video, we're going to begin our review or our recap of sphingolipids. So let's first start by revisiting our lipid map. And so we know that we're currently exploring the fatty acid based lipids. And already in our previous lesson videos, we've covered the glycerolipids including triacylglycerols and glycerophospholipids, as well as the most common variable head groups of these glycerophospholipids. And we've also covered the sphingolipids, including sphingophospholipids and sphingomyelin, as well as the sphingoglycolipids, including cerebrocytes, globocytes, and gangliosides. And so here in this topic, we're specifically doing a review of the sphingoglycolipids, which would include everything that we see highlighted right here. And so essentially we're just doing a review of what we have circled right here. And, what we have circled here is really just gonna show up in our table down below which we'll talk about in our next lesson video. So I'll see you guys there to do some more review.
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Sphingolipid Recap
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And so again, everything that we're going to be talking about in this video is really just review from our previous lesson videos. And so if you're already feeling good on the classes of single lipids, then feel free to skip this video if you'd like. But if not, stick around because this video might help you guys put everything together. And so again, we're going to be reviewing the different classes of sphingolipids. So, essentially, reviewing this branch right here of our lipid map. And so just like Glycerophospholipids over here are classified according to their variable head groups, sphingolipids are also classified according to their variable head groups. And so, notice down below what we have is the structure of a typical sphingolipid. And notice that the variable head group is right here. And so, simply by changing the variable head group, we can change the class of sphingolipid. And not only does the variable head group, dictate the structure in the class of the sphingolipid, again, it's also going to dictate the function of the sphingolipid as well. Now, very similarly to Glycerophospholipids, sphingolipids over here. They can also vary in their fatty acid length and degree of saturation. So, these can vary or these, also varies among, the molecules in each class. And so if we take a look at this table down below, again, it's really just gonna be review from our previous lesson videos. And notice we have the sphingolipid class here in the 1st column and then we have the variable head group that's associated, over here in the second column. And so you might recall that ceramides are practically the simplest type of sphingolipid. And that's because their variable head group is literally just a hydrogen atom. So you just put a hydrogen atom here, and you've got yourself a ceramide. And the amide here in the ceramide lets you know that the fatty acid in the the variable fatty acid here is going to be linked via an amide linkage. And really that's the most distinct feature of the sphingolipid uh-uh classes. All the sphingolipids. Now, the next row that we have here are the the sphingomyelin, class of syngolipids and these are a you might recall sphingophospholipids and so here we're showing you phosphocholine as the variable head group. And, you can see that it has a phosphate group and, it has this choline group over here as well. And then notice down below we're showing you cerebro sides which are, a type of sphingoglycolipid and the glyco here is indicating sugar. So, we can go ahead and write sugar here. And so you can see that it does indeed have just one sugar unit. And for example here, we're showing you Glucosal Cerebroside which, means that it has a glucose residue as the variable head group. And then if we wanted to get a globo side, which you might notice is not on this table, but if we wanted to get a global side, all we would have to do is add a second sugar residue. So multiple sugar residues would give us the global side. And so, down below, last but not least, what we have are the gangliosides, which you might recall, containing complex oligosaccharide as the variable head group that is going to be branched as we can see here and it contains a cialic acid residue. And the cialic acid residue is typically NEU 5A c. And so this here concludes our review of, sphingophospholipids and the classes of sphingophospholipids. And if you take, some time to be able to review the lipid map and review this table down below, then you guys should be good on sphingolipids. And we'll also be able to get some practice applying all of these concepts in the next couple of practice videos. So I recommend you guys try those out, and I'll see you guys there.
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Problem
Problem
Which of the following is TRUE of sphingolipids?
A) They always contain glycerol and fatty acids.
B) They may be charged, but are never amphipathic.
C) Phosphatidylcholine is a typical sphingolipid.
D) They contain only one esterified variable fatty acid.
E) Cerebrosides, globosides and gangliosides are sphingolipids.
A
They always contain glycerol and fatty acids.
B
They may be charged, but are never amphipathic.
C
Phosphatidylcholine is a typical sphingolipid.
D
They contain only one esterified variable fatty acid.
E
Cerebrosides, globosides and gangliosides are sphingolipids.
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example
Sphingolipid Recap Example 1
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Video transcript
Alright. So at this point in our course, we've covered a lot of different types of lipids and introduced a lot of prefixes, including glycero, sphingo, and glyco. And so I can admit it can be pretty confusing at times. And so here, what we have is an example problem that's hopefully gonna help put things in perspective for you guys. And so this example problem wants us to appropriately match each of the following 6 lipid molecules that we see down below with one of the listed types of lipids that we see here. And so taking a look at this first lipid molecule that we see, one of the first things that you guys should notice about this is that it has a glycerol based backbone. And so here what we have is a platform that is derived from glycerol. Another thing that you guys should notice is that we've got these hydrocarbon chains here and so these are certainly going to be our fatty acids. And, another thing that you guys should note is that these fatty acids are linked to the glycerol via these ester linkages that we see here. And so we can go ahead and label these as esters. And so, what's important to note is that there are actually 3 fatty acid chains linked to a glycerol molecule. And so we know that this is going to be a glycerolipid. But because there are specifically 3 fatty acid chains, of course, that is going to correspond with the trie. And so the tri is indicating that there are 3 and so, of course, this is going to be a triacylglycerol and so down below, we can go ahead and label this as a triacylglycerol and then, what we can do is go ahead and cross this off our list. Glycerol based platform and the reason for that is glycerol based platform. And the reason for that is because notice that we have this, trans double bond that is present here. And, we have this 18 carbon platform. And really, this is going to be a sphingosine based form. And so we know that this is going to be some kind of sphingolipid. And another way to, recognize that this is a sphingolipid is that notice that this fatty acid chain is actually linked not via an ester linkage like what we had over here. It's actually being linked via an amide linkage and so here what we can do is label this as an amide and again, that's another way to identify this as not being a glycerol molecule and as being a sphingosine molecule. And again, you can see here that there is a phosphate group attached to this sphingosine molecule and so that must mean that this is a sphingophospholipid. And of course the only sphingophospholipid that we talked about in our previous videos was sphingomyelin and so here what we have is a phosphoethanolamine head group and so, what we can do is go ahead and label this as a, sphingo myelin molecule. And then, of course, we can cross it off our list. Now, moving on to the next lipid molecule that we have over here. What we need to recognize is again, what we have here is a glycerol based platform. And so this is going to be another glycerolipid. But this time, notice that there is a phosphate group here attached to this glycerol backbone. So we know that this must be a Glycerophospholipid. And again, we've got these 2 fatty acid chains and the 2 fatty acid chains notice are linked to the glycerol backbone via ester linkages once again. And notice that the head group here branching off of this platform here actually does resemble another glycerol molecule that we have over here. And so really this is another glycerol molecule that is branching off of this Glycerophospholipid. And so, what this means is that it must be some kind of Glycerophospholipid that has a glycerol in it. And you might recall from our previous lesson videos that phosphatidate was actually the simplest glycerophospholipid. And so the phosphatide here is indicating that this is a glycerophospholipid. And of course the ill glycerol is saying that there's a glycerol molecule branching off and so essentially, what we're saying is that here because we have a another glycerol molecule branching off. This must be a phosphatidylglycerol molecule and indeed, it is. So, we can go ahead and label that down below. Phosphatidyl, glycerol, and then, of course, we can cross this off our list up above. So, then, moving on to this lipid over here. Again, what we need to recognize is looking at this platform that this is not going to be a glycerol, platform. Instead, what we can see is that there is a trans double bond here and we've got this 18 carbon amino alcohol once again. So you can see, the amide linkage here once again. And so, of course, this means that this is going to be a sphingosine platform right here. And, you can see that the fatty acid chain here is, linked via the amide. And notice that this time, the variable head group does not have a phosphate group like it did previously. The variable head group here is actually a sugar residue and you might recognize this sugar residue as being a glucose molecule and so there's only one glucose here. There's only one sugar residue branching off of this phingosine, platform here. And so, because there's only one sugar residue, of course, this is gonna correspond with the cerebro side from our previous lesson video. So we can go ahead and label this as a cerebro side. And that's how we identify that one. So now we're down to just 2 more molecules and, looking at this one over here on the left, what you'll notice is again, it has a glycerol based backbone. And so, what you can see is that there are no amide linkages. Instead, we have the ester linkages once again. We have these fatty acid chains that are connected via the ester linkages, And then we have a phosphate group branching off of the glycerol. So we know again that this is another glycerophospholipid. And so, what you'll note is that the variable head group branching off here kind of looks like an amino acid. It has an amino group, it has a carboxyl group, it has a central carbon, and a central hydrogen, and then this would be the R group. And, at a closer look, if this oxygen right here were, a hydroxyl group, if it were an Oh group, then that would be the amino acid serine And so this is going to be a serine head group here. And so of course, once we consider that, we know that, this must be the phosphatidylserine here. Again, the phosphatid is gonna be the phosphatidate prefix indicating a glycerophospholipid. The ill is indicating the branching of a serine molecule. Serine. And serine. And then of course, we can cross that one off our list. And we also already covered cerebroside previously and so the only one that's left now is linoleate and that one may not sound familiar to you guys because this is the common name of a fatty acid and even though we have not yet or even though we did not talk about the common naming system in a lot of detail, clearly, this is a fatty acid. You can see that there's a long hydrocarbon chain here and we've got the, carboxylic acid group over here and so, this is indeed going to be linoleate. And so that is it. This concludes our practice problem here and hopefully, the strategies that we use to determine each of these molecules will be able to help you guys out. And so, I'll see you guys in our next video.
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Problem
Problem
Match the following lipid types with the correct description.
A) Fatty acid. _____ 1. Membrane lipids with a glycerol backbone.
B) Triacylglycerol. _____ 2. Phospholipid especially common in nerve cells.
C) Phospholipid. _____ 3. One of the simplest forms of a glycolipid.
D) Sphingosine. _____ 4. Lipids covalently attached to carbohydrate groups.
E) Glycerophospholipid. _____ 5. Chains of hydrogen-bearing carbon atoms with a carboxylic acid.
F) Sphingomyelin. _____ 6. Complex glycolipids with a sialic acid residue.
G) Glycolipid. _____ 7. A complex amino alcohol backbone for membrane lipids.
H) Cerebroside. _____ 8. Major class of membrane lipids.
I) Ganglioside. _____ 9. Long-term storage form of fatty acids.