Sphingomyelins - Online Tutor, Practice Problems & Exam Prep

Sphingolipids, characterized by a sphingosine backbone, consist of an 18-carbon amino alcohol with specific functional groups. Sphingomyelins, a type of phospholipid, feature a sphingosine backbone linked to one fatty acid via an amide bond, along with a phosphate and choline head group. These lipids are crucial structural components of the myelin sheath, which insulates nerve fibers, highlighting their importance in biological systems. Understanding these structures aids in grasping lipid classification and their functional roles in cellular membranes.

Sphingomyelins Concept 1

Now before we can talk about sphingomyelins, we first need to talk about sphingolipids. These are lipids that have a sphingosine backbone. We're going to say that sphingosine itself is an 18-carbon amino alcohol. Some key characteristics of sphingosine are that carbons 1 to 3 are analogous to glycerol. Here, you'll notice that we typically number from 1 down to 3 when we talk about other types of fatty acids, but here it's inverted on its head. So one starts here on the bottom and moves up to 3. We're going to say carbons 1 to 3 are analogous to glycerol, so they have -OH groups on those carbons.

Next, we're going to say that our amino group, which is NH2, is at carbon number 2, so there's an NH2 here. Then, we're going to say 15 carbons are attached to carbon 3. We have this long chain that comes out to 15 carbons because remember it's 18 carbons: 1 to 3 here, and then the other 15. Finally, we're going to say we have a trans double bond at carbon number 4. With this information, that's how we're able to create this image of a typical sphingosine. Just remember, we're talking about sphingolipids, which are lipids that have a sphingosine backbone. Sphingosine itself has these characteristics that make it unique.

Sphingomyelins Concept 2

This video, we're going to take a look at our sphingomyelins. Now sphingomyelins are phospholipids, and here instead of having a glycerol backbone, they have a sphingosine backbone, and that sphingosine backbone is attached to only one fatty acid. Now, here we would say that the phosphate and choline head group form the head. We're going to say one tail is sphingosine and the other tail is a fatty acid attached by an amide bond. If we take a look here, remember that our lipids, they're broken down first into hydrolyzable and non-hydrolyzable. Here, looking at the hydrolyzable portion, we're looking at our sphingolipids. Sphingolipids would branch down to our sphingomyelins which is one of 2 groups that are classified as our phospholipids. Here we can see that we have our choline head group, we have our phosphate group, we have our sphingosine backbone here, and we have our fatty acid here, but now it is an amide bond involved. And, that would give us our sphingomyelin. Now, here sphingomyelin are primary structural components of the myelin sheath which deal with nerve fiber coatings. So, remember this is something that you might have learned if you've already taken biology or anatomy, the importance of our sphingomyelin structures. Right. So just keep in mind the structural importance of these sphingomyelins, and how they themselves are part of phospholipids.

Sphingomyelins Example 1

For this example question, it asks which one of the following statements about sphingomyelins is incorrect? Here, the fatty acid at carbon 2 is attached through an amide linkage. That is true, so this can't be an answer. The base molecule in sphingomyelins is sphingosine. That is also true. It's not glycerol like we've seen in other molecules; it's sphingosine. Sphingomyelins are essential for the structural integrity of the myelin sheath. This is an important fact concerning sphingomyelin. So, this is also true. The odd one out is option d. Let's see why that is. A sphingomyelin has only one tail because it contains one fatty acid. So, here we have a fatty acid chain at carbon number 2, but it has more than one tail. It also has a hydrocarbon tail at carbon number 3, but we have also the presence of that trans double bond. Therefore, this statement is incorrect. The answer would be option d. This is the only incorrect statement out of the 4 given to us.

Sphingomyelins Example 2

In this video, we're going to talk about drawing sphingomyelins. Drawing the sphingomyelin requires recalling the structures of the sphingomyelin, sphingosine, and the fatty acids involved. Now, here it says, draw the structure of a sphingomyelin that contains oleic acid. Remember, Oleic Acid represents an unsaturated fatty acid. Its standard notation or shorthand notation is 18:1, meaning that we have an 18 Carbon fatty acid chain, 1 means we have 1 pi bond, and with these unsaturated fatty acids with 1 pi bond, it's typically at carbon number 9 where we first see it. Alright.

So now come down here, we're going to say step 1 is to draw the sphingosine backbone with a phosphate group at carbon number 1. So here goes carbon number 1, and there's a phosphate group there. We're going to say instead of an NH₂ group at carbon number 2, we're going to write only NH. So here there's going to be an NH group right here. And that's because we're going to attach something to that NH group.

Step 2, we're going to extend the phosphate at carbon number 1 with the choline head group. Remember, we're not spelling choline, Co. Choline head group. So, remember choline CH gives us a clue on the groups attached to the nitrogen. So in choline, we have an ethyl group attached to the oxygen, and then we have nitrogen. Choline is CH₃, nitrogen is connected to three CH₃s because it's making 4 bonds, it's positively charged.

And then coming down to step 3, we're going to draw the fatty acyl group, so the fatty acid without the OH, from the NH group at carbon number 2. So here goes our amide linkage or amide bond that's going to be formed. So here, remember, oleic acid is an unsaturated fatty acid. Its standard or shorthand notation is 18:1. So we have 18 carbons, so we have 2, 4, 6, 8, 10, 12, 14, 16, 18 carbons. Just to be sure. This would be the structure of our sphingomyelin based on the information given to us within the example question. We have our amide bond on Carbon number 2 in terms of its NH group. We have our phosphate group, as well as the choline head group on carbon number 1. And of course, on carbon number 3, we have our 15 carbon chain that's also containing a trans double bond. Alright, so this would be our final answer.

Draw a sphingomyelin that contains palmitoleic acid.

• A.
• B.
• C.
• D.

Which one of the following statements describes how sphingomyelins are similar to glycerophospholipids?

• A. Sphingomyelins have the same number of fatty acids as glycerophospholipids.
• B. Sphingomyelins and glycerophospholipids have the same linkage that holds the fatty acids.
• C. Sphingomyelins and glycerophospholipids have phosphate with head groups.
• D. Both can be classified as sphingolipids.

Which one of the following statements is incorrect about triacylglycerols and phospholipids?

• A. Triacylglycerols contain glycerol while phospholipids do not.
• B. Phospholipids have a phosphate group attached at C3.
• C. Phospholipids and triacylglycerols contain 2 and 3 fatty acids, respectively.
• D. Due to polar head groups, phospholipids have a higher water solubility than triacylglycerols.

Here’s what students ask on this topic:

What is the structure of sphingosine and how does it differ from glycerol?

Sphingosine is an 18-carbon amino alcohol with a specific structure. It has hydroxyl groups (OH) on carbons 1 and 3, an amino group (NH₂) on carbon 2, and a long hydrocarbon chain extending from carbon 3 to carbon 18. Additionally, there is a trans double bond at carbon 4. In contrast, glycerol is a 3-carbon molecule with hydroxyl groups on each carbon. The key difference is that sphingosine has a longer carbon chain and an amino group, whereas glycerol is a simpler molecule with only hydroxyl groups.

What are sphingomyelins and what role do they play in the body?

Sphingomyelins are a type of phospholipid that have a sphingosine backbone instead of a glycerol backbone. They consist of a sphingosine molecule attached to one fatty acid via an amide bond, and a phosphate group linked to a choline head group. Sphingomyelins are crucial components of the myelin sheath, which insulates nerve fibers and facilitates the rapid transmission of nerve impulses. This makes them essential for proper nervous system function.

How are sphingomyelins classified within the broader category of lipids?

Sphingomyelins are classified as phospholipids within the broader category of sphingolipids. Sphingolipids are lipids that have a sphingosine backbone. Sphingomyelins, specifically, are characterized by having a sphingosine backbone attached to one fatty acid via an amide bond, and a phosphate group linked to a choline head group. This classification places them under hydrolyzable lipids, which can be broken down into smaller molecules through hydrolysis.

What is the significance of the myelin sheath and how do sphingomyelins contribute to its function?

The myelin sheath is a protective covering that surrounds nerve fibers, facilitating the rapid transmission of electrical impulses along the nerves. Sphingomyelins are a primary structural component of the myelin sheath. They contribute to its function by providing structural integrity and insulation, which helps in the efficient conduction of nerve signals. This is crucial for proper nervous system function, including muscle coordination and sensory perception.

What is the chemical composition of sphingomyelins?

Sphingomyelins are composed of a sphingosine backbone, one fatty acid attached via an amide bond, a phosphate group, and a choline head group. The sphingosine backbone is an 18-carbon amino alcohol with specific functional groups: hydroxyl groups on carbons 1 and 3, an amino group on carbon 2, and a long hydrocarbon chain. The fatty acid is linked to the amino group of sphingosine, forming an amide bond, while the phosphate and choline form the polar head group.