Concept 5.3: Lipids are a diverse group of hydrophobic moleculesLipids are the one class of large biological molecules that does not include true polymersThe unifying feature of lipids is that they mix poorly, if at all, with water Lipids are hydrophobic becausethey consist mostly of hydrocarbons, which form nonpolar covalent bondsThe most biologically important lipids are fats, phospholipids, and steroids