sentences:  Phosphatidylethanolamine is an important precursor, substrate, or donor in several biological pathways.As a polar head group, phosphatidylethanolamine creates a more viscous lipid membrane compared to phosphatidylcholine.For example, the melting temperature of di-oleoyl-phosphatidylethanolamine is -16 °C while the melting temperature of di-oleoyl-phosphatidylcholine is -20 °C.