The term "lipid" covers an extremely diverse range of chemical or molecular species. Lipids, defined as molecules that are sparingly soluble in water but readily soluble in organic solvents, are broadly categorized into "neutral " or "apolar" lipids, and "amphiphilic” or "polar" lipids. Neutral lipids will include simple hydrocarbons, carotenes, triacylglycerols, wax esters, sterol eaters, as wel1 as other lipids such as fatty acids, polyprenols, and sterols In which the hydrophilic function has little Impact on the overall molecular characteristics. Polar lipids include phospholipids, glycolipids, sulfolipids, some sphingolipids, oxygenated carotenoids and chlorophylls.