Question

A common structural feature of membrane lipids is their amphipathic nature. For example, in phosphatidylcholine, the two fatty acid chains are hydrophobic and the phosphocholine head group is hydrophilic. For each of the following membrane lipids, name the components that serve as the hydrophobic and hydrophilic units: (a) phosphatidylethanolamine; (b) sphingomyelin; (c) galactosylcerebroside; (d) ganglioside; (e) cholestrol.

Answer 1

Answer:

A. Phosphatidylethanolamine:

phosphoethanolamine (hydrophilic) 2 fatty acids (hydrophobic )

B. Sphingomyelin:

phosphocholine (hydrophilic) ceramide (sphingosine + 1 fatty acid) (hydrophobic )

C. Galactosylcerebroside:

D-galactose (hydrophilic) ceramide (hydrophobic )

D. Ganglioside:

oligosaccharide (hydrophilic) ceramide (hydrophobic )

E. Cholesterol:

-OH group (hydrophilic) hydrocarbon ring skeleton (hydrophobic )

Explanation:

The amphipathic nature of lipids shows  that all lipids have a hydrophilic (water-loving or polar end) and a hydrophobic  (water fearing or non-polar end.)

The various lipids in question, and their ampiphatic groups are detailed above.