Draw the structure of the sphingomyelin that contains a myristic acid acyl group. Identify the hydrophilic head group and the hydrophobic tails in this molecule.

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Hi, everyone. Let's take a look at the next problem. The following structure of sphingomyelin with a linoleic acid fatty acid contains an inaccuracy, identify and correct the error in the structure. So when we look at the structure, it's big and complex, but let's break it down into the component parts of single myelin and look at each part and see if we can spot where the structure has gone wrong. So we call it sphingomyelin is a major component of a mammalian cell membranes, uh particularly the myelin sheath, thus its name. And so we're expecting a small hydrophilic part and then a long hydrophobic chain. And we can see that we have these long hydrocarbon chains on here. We know we've got a fatty acid chain. And we can see with fatty acid, we know it ends in a carboxylic acid. And we can see that carboxylic acid derived group with the carbon bond there on the right side of the structure. So that carbon group and in the long hydrocarbon chain, there is going to be the linoleic acid portion. But let's break it down, think about the components and then identify them on our structure So this backbone of a fing myelin is gonna be a sphingosine group or a sphingosine molecule. Really, I should say, which is an 18 carbon amino alcohol with an unsaturated hardy carbon chain. And so that's sort of part one. And then we have the fatty acid, which we just mentioned and we've already kind of located that on here. And then this third portion is our hydrophilic portion, which is the phos foc Colline, which consists of an amino alcohol attached to a phosphate group. So that's going to be the easiest to spot here. We're looking for charged portions and we're looking for that phosphate group. So we'll go ahead and highlight that in pink for our phospholine. And here's our phosphorus, there's our phosphate group. And you can see right next to it is that amino portion. So that's our hydrophilic part. That's the phospholine. So we just have our sphingosine and fatty acid, the Fingen and fatty acid together portion is also known as a ceramide. So that's convenient to be aware of if you run across that term. So our sphingosine, we we can see we have our uh phosphate attached to one of the alcohol groups. So our backbone highlight that in yellow. So this finger scene in yellow starts where the phosphate group is attached, that would have been an alcohol group there attached to the phosphate and then we have another carbon, another carbon with an alcohol group, another one. So now, I've got 1234 carbons. We've got that double bond. We know there needs to be an unsaturated bond in there. And then how many more carbons do we have? So, 12345 and then we see we have CH two with a 12 subscript, so 12 more. So 17 and then a final CH three, so 18 carbons. So that is our sphingosine backbone, proper number of carbons unsaturated. And we've got our alcohol groups. But what are we missing? Well, it's an amino alcohol. And if we look, there's no other nitrogen groups only in the phosphor coline, we are missing a nitrogen. And that's where let's look at our fatty acid. The piece of fatty acid should be joined to this finger scene backbone by an amid bond. So let's highlight our fatty acid in blue. It's linoleic acid and we could look up the structure of linoleic acid. But let's pay attention to the connections here before we sit here and figure out if this is specifically, well, soon for now, it's correct. So there is that long hydrocarbon chain, here's the carbonyl group. But what is joining our sphingosine backbone? And our fatty acid there is going to be the error. So we have an oxygen, we have an ester bond attaching these two instead of an amid bond. So there's our error. So we'll put error is this oxygen and correct the error. This should be a nitrogen So I'll put a big and here instead, and that nitrogen should have one more hydrogen on it. So I'm going to erase that and to make, put it down closer. So we'll x out the oxygen. This should be an N and a hydrogen attached to it. So our air, there is an ester bond instead of an amid bond, that oxygen should be a nitrogen. And again, we can spot that both, by the way, the fatty acid should be joined. And then the fact that we know our sphingosine needs to be an amino alcohol and there's no nitrogen there. So that's our error. There's our correct correction to our structure for the structure of sphingomyelin. See you in the next video.

Draw the structure of the sphingomyelin that contains a myristic acid acyl group. Identify the hydrophilic head group and the hydrophobic tails in this molecule.

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Key Concepts

Sphingomyelin Structure

Hydrophilic and Hydrophobic Regions

Myristic Acid Acyl Group