Lipids are the most efficient energy storage molecules in cells.
Most of the structure of lipids is very non-polar, formed almost exclusively of carbon and hydrogen atoms. The presence of long, hydrophobic fatty acid chains is a key feature to use in identifying many important lipids. Polar Lipids are Amphipathic Molecules Amphipathic molecules have a charged region and a highly hydrophobic region Polar lipids form micelles or bilayers in aqueous solution. Other lipids Caratenoids and vitamin A are used for sensing light or vision. The steroids are chiefly hormones, including estrogen and testosterone.