Glycerol is a small organic molecule that contains three carbon atoms. Cholesterol, on the other hand, is a much larger organic molecule with 27 carbon atoms. Glycerol, which is manufactured from the propylene that comes from the refinement of petroleum, has many commercial uses. Cholesterol, synthesized in the liver, has an important role in the body because it is a vital component of the cell membrane, the material that encloses all of the contents of the cell.
Properties of Glycerol
Glycerol is in a class of organic compounds called alcohols. It contains a straight chain of three carbon atoms with an alcohol group bonded to each carbon. It can therefore form three ester bonds to compounds like fatty acids. The formation of these three ester bonds with various fatty acids in the body creates compounds called triglycerides, which the body stores as fat for later conversion to energy. Physically, glycerol is a thick, colorless liquid that melts at 64 degrees Fahrenheit and boils at 554 degrees Fahrenheit. It dissolves completely in water.
Uses for Glycerol
In addition to its function as the backbone for the triglycerides, glycerol has another biological application that involves its use as a protecting agent in the process of freezing tissue such as corneas, red blood cells and sperm cells. Scientists have found that glycerol prevents the formation of intracellular ice crystals, which can damage the tissue or even cause tissue death. Commercial applications of glycerol include automobile and exterior house paints and emulsifiers for baked goods and ice cream. It is also used as a component of pharmaceutical products such as mouthwashes, cough medicines, vaccines, serums and suppositories.
Properties of Cholesterol
Cholesterol, which is an organic compound classified as a steroid, appears as a wax-like solid. Its structure differs from that of glycerol in that it is a much larger molecule. Its predominant feature is the presence of four carbon rings. There are no rings in glycerol. Also unlike glycerol, cholesterol does not dissolve in water. This is why it can't be transported through the bloodstream without a lipoprotein carrier.
Biological Function of Cholesterol
In addition to being an integral part of the cell membrane, cholesterol is also the starting material for the body's synthesis of the steroid hormones, such as testosterone, and for its synthesis of vitamin D and the bile acids. The bile acids, produced in the liver and stored in the gall bladder, facilitate the digestion of fats. Scientists have determined that there are two types of cholesterol circulating in the bloodsteam -- LDL or "bad" cholesterol and HDL or "good" cholesterol. It is important for a person to have a high level of HDL cholesterol because this material helps prevent the LDL cholesterol from building up on the walls of arteries.
