Figure 11-6 A phosphatidylcholine mole cule.It is represented (A)schematically. (B)in formula.(C)as a space-filling model. and (D) as a symbol.This particular phos- pholipid is built from five parts:the hydrophilic head,choline,is linked via a phosphate to glycerol,which in turn is linked to two hydrocarbon chains,forming the hydrophobic tail.The two hydro- carbon chains originate as fatty acids that is.hydrocarbon chains with a-COOll group at one end-which become attached to glycerol via their-COOH groups.A kink in one of the hydrocarbon chains occurs where there is a double bond between two carbon atoms:it is exaggerated in these drawings for empha sis.The phtosphatidyl-part of the name of phospholipids refers to the phosphate- glycerol-fatty acid portion of the molecule CHOLINE ead PHOSPHATE GLYCEROL 88be HYDRO RBON 心 IA) 6