Final answer:
Sphingomyelins and glycerophospholipids have structures suitable for forming lipid bilayers, with hydrophilic heads and hydrophobic tails aligning appropriately to create a barrier critical for cellular membrane function.
Step-by-step explanation:
Of the molecules listed, sphingomyelins and glycerophospholipids have the necessary structure to form a lipid bilayer. Both these types of molecules consist of hydrophilic heads and hydrophobic tails. Sphingomyelins are unique in that they are derived from sphingosine, not glycerol, but they still align to form bilayers in a similar fashion due to their polar head groups and non-polar tails. Glycerophospholipids, on the other hand, have a glycerol backbone and can easily align with their hydrophilic phosphate-containing heads facing outward and their hydrophobic fatty acid tails facing inward to create a bilayer. This arrangement is critical for the structure and function of cellular membranes, as it provides a stable barrier that separates the intracellular and extracellular environments. Sphingomyelins can even be found in the myelin sheath of nerve cells. Triacylglycerols (or triacylglycerides), fatty acids, and cholesterol molecules do not form bilayers.