Membrane Lipids

Membrane lipids are a group of compounds (structurally similar to fats and oils) which form the double-layered surface of all cells. The three major classes of membrane lipids are phospholipids, glycolipids, and cholesterol. Like magnets, membrane lipids have polarity with one end that is soluble in water ('polar') and an ending that is soluble in fat ('nonpolar'). By forming a double layer with the polar ends pointing outwards and the nonpolar ends pointing inwards membrane lipids can form a 'lipid bilayer' which keeps the watery interior of the cell separate from the watery exterior. The arrangements of lipids and various proteins, acting as receptors and channel pores in the membrane, control the entry and exit of other molecules as part of the cell's metabolism.