For each of the following amphipathic molecules, indicate which part of the molecule is hydrophilic: phosphatidyl serine, sphingomyelin, cholesterol, and triacylglycerol?

Answer: 1. Phosphatidyl serine: the phosphoserine group

2. Sphingomyelin: the phosphocholine group

3. Cholesterol: the hydroxyl group

4. Triacylglycerol: the ester bond between glycerol and fatty acids.

Explanation:

Amphipathic molecules have parts that are hydrophobic and hydrophilic. The cell membrane is made up of amphipathic molecules.

Phosphatidyl serine has a polar (hydrophilic) head named the phosphoserine group, the fatty acid group forms the chain.

Sphingomyelin consist of phosphicholine and ceramide. The phosphocholine group is the hydrophilic part while the ceramide is the hydrophobic part.

Cholesterol contains a hydroxyl group (-OH) that is polar while the rest part of the cholesterol is non polar.

Triacylglycerol is made up of glycerol and 3 fatty acid chains. The ester bonds between glycerol and the fatty acids is the Polar part of triacylglycerol.