Outer or inner membranes of a cell are composed of lipid molecules. Membrane lipid of Eukarya and Bacteria are ester lipid, which consists of fatty acid and glycerophosphate, while that of Archaea consists of ester lipid made of isopranyl alcohol and glycerophosphate. Hydrophobic chains and grycerophosphate are connected by ether bonds in Archaea while they are connected by ester bonds in Bacteria and Eukarya. Stereo specificity of glycerophosphate of hydrophobic core in archaeal lipid is different form that in ester lipid.