3. The chemical composition of membranes A. Membrane Lipids: The Fluid Part of the model x Membrane lipids are amphipathic. .There are three major classes of lipids: Phospholipids: Phosphoglyceride and sphingolipids Glycolipids Sterols( is only found in animals)3. The chemical composition of membranes A. Membrane Lipids: The Fluid Part of the Model Phospholipids: Phosphoglyceride and sphingolipids Glycolipids Sterols ( is only found in animals) ❖Membrane lipids are amphipathic. ❖There are three major classes of lipids: