What is a characteristic of glycerophospholipids?

Glycerophospholipids are a class of lipids that are key components of cell membranes. A defining feature of glycerophospholipids is their structure, which consists of a glycerol backbone attached to two fatty acid chains and a phosphate group, which in turn can be linked to various polar head groups.

The characteristic that correctly identifies glycerophospholipids is the presence of a polar head group attached to the C3 position of glycerol. This unique configuration allows glycerophospholipids to form bilayers in aqueous environments, creating the structural basis for cell membranes. The polar (hydrophilic) head group interacts with the surrounding water, while the fatty acid (hydrophobic) tails point inward, away from the water.

In contrast, the other options do not accurately describe glycerophospholipids. For instance, the presence of three fatty acid chains is typical of triglycerides, not glycerophospholipids. The statement about unsaturated chains being primarily at the C1 position is misleading, as both C1 and C2 can contain unsaturated fatty acids, but there isn't a specific preference for C1. Lastly, glycerophospholipids do contain ester bonds, as the fatty acids