What structural features distinguish sphingolipids from glycerolipids, and how is the fatty acid attached in sphingolipids?
Sphingolipids use sphingosine, an 18-carbon amino alcohol with a trans double bond, as their backbone instead of glycerol. They contain only one variable fatty acid, which is attached via an amide bond at the C2 position, unlike glycerolipids that have two variable fatty acids attached via ester bonds.