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Ch.23 Lipids
McMurry - Fundamentals of General, Organic, and Biological Chemistry 8th Edition
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187Not the one you use?Change textbook
All textbooksMcMurry 8th EditionCh.23 LipidsProblem 14
Chapter 23, Problem 14

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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Understand the structure of sphingomyelin: Sphingomyelin is a type of sphingolipid that consists of a sphingosine backbone, a fatty acid chain attached via an amide bond, and a phosphocholine or phosphoethanolamine head group attached to the sphingosine backbone via a phosphate group.
Identify the myristic acid acyl group: Myristic acid is a saturated fatty acid with the chemical formula CH₃(CH₂)₁₂COOH. When it forms an acyl group, the hydroxyl group (-OH) of the carboxylic acid is removed, leaving CH₃(CH₂)₁₂CO-.
Attach the myristic acid acyl group to the sphingosine backbone: The myristic acid acyl group is connected to the amine group (-NH₂) of the sphingosine backbone via an amide bond. This forms the hydrophobic tail of the sphingomyelin molecule.
Add the hydrophilic head group: The hydrophilic head group in sphingomyelin is typically phosphocholine (or phosphoethanolamine). This group is attached to the hydroxyl group on the sphingosine backbone via a phosphate group, making it polar and hydrophilic.
Label the hydrophilic head group and hydrophobic tails: The phosphocholine (or phosphoethanolamine) group is the hydrophilic head, while the myristic acid acyl group and the hydrocarbon chain of the sphingosine backbone form the hydrophobic tails. These regions give sphingomyelin its amphipathic nature, which is important for its role in cell membranes.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Sphingomyelin Structure

Sphingomyelin is a type of sphingolipid that consists of a sphingosine backbone, a fatty acid, and a phosphocholine head group. The structure features a long hydrophobic tail formed by the fatty acid chain, which in this case is myristic acid, a saturated fatty acid with 14 carbon atoms. Understanding the arrangement of these components is crucial for visualizing the molecule's overall structure.
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Sphingomyelins Example 2

Hydrophilic and Hydrophobic Regions

In sphingomyelin, the hydrophilic head group is the phosphocholine moiety, which interacts favorably with water due to its polar nature. Conversely, the hydrophobic tails consist of the sphingosine and myristic acid components, which repel water and are oriented away from the aqueous environment. This amphipathic nature is essential for the formation of biological membranes.
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Fatty Acids Concept 1

Myristic Acid Acyl Group

Myristic acid is a saturated fatty acid with a 14-carbon chain, commonly found in various lipids. When it is attached to the sphingosine backbone in sphingomyelin, it contributes to the hydrophobic tail of the molecule. Recognizing the specific acyl group is important for understanding the lipid's properties and its role in membrane dynamics.
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Related Practice
Textbook Question

Which of the following terms apply to the compound shown below? (Hint: Look at the functional groups and the bonds involved to begin analyzing the compound part by part in comparison to the lipids discussed in this chapter.)

a. A phospholipid

Textbook Question

Write the complete equation for the hydrolysis of a triacylglycerol in which the fatty acids are two molecules of stearic acid and one of oleic acid.

Textbook Question

Draw the structure of the glycerophospholipid that contains a stearic acid acyl group, an oleic acid acyl group, and a phosphate bonded to ethanolamine.

Textbook Question

Identify the products formed by complete hydrolysis of all ester bonds in (a) the phosphatidylcholine on page 726.

Textbook Question

Identify the products formed by complete hydrolysis of all ester bonds in (b) the sphingomyelin in Figure 23.5.

Textbook Question

Which of the following terms apply to the compound shown below? (Hint: Look at the functional groups and the bonds involved to begin analyzing the compound part by part in comparison to the lipids discussed in this chapter.)

e. A lipid