A: CTP plays an important role in the synthesis of phospholipids, and is necessary for the synthesis of CDP- ethanolamine, CDP- choline and CDP- diglyceride. In the synthesis process of phosphatidylcholine and phosphatidylethanolamine, energy is provided by CTP at first, and CDP- choline and CDP- ethanolamine are generated under the action of enzymes. As donors of active choline and ethanolamine, they condense with diglycerides to produce lecithin and cephalin. In the synthesis process of phosphatidylinositol, phosphatidylserine and glyceryl diphosphate (cardiolipin), CTP provides energy to generate activated CDP- diglyceride, which is then condensed with serine and inositol superphosphate to generate phosphatidylinositol, phosphatidylserine or glyceryl diphosphate.