Membrane Structure and Function Membrane Structure and Function Review of lipid structure Architecture of Membranes Subcellular fractionation techniques can partially separate and purify several important biological membranes, including the plasma and mitochondrial membranes, from many kinds of cells. These preparations are often contaminated with membranes from other organelles. However, the plasma membranes from human erythrocytes can be isolated in near purity because these cells contain no internal membranes.
All membranes contain phospholipids and proteins.
Because of its high phospholipid content, myelin can electrically insulate the nerve cell from its environment. The lipid composition varies among different membranes. All membranes contain a substantial proportion of phospholipids, predominantly phosphoglycerides, which have a glycerol backbone. All membrane phospholipids are amphipathic, having both hydrophilic and hydrophobic portions. Sphingomyelin, phospholipid that lacks a glycerol backbone, also is commonly found in plasma membranes.