Cholesterol, 25g (C08-0503-157)

Cholesterol is the principal sterol of the higher animals, found in all body tissues. It is the main constituent of gallstones and all biological membranes. Approximately 25% of total brain lipid is cholesterol. Cholesterol, followed by the chemical suffix -ol for an alcohol, is an organic chemical substance classified as a waxy steroid of fat. Cholesterol is suitable for use in liposome preparations. Cholesterol is a component used for the preparation and study of artificial model membranes. One example is a study of valinomycin induced changes in membrane potentials of red blood cell and phospholipid (phosphatidylcholine from egg yolk plus cholesterol) vesicle suspensions. Positively charged cyanine dyes were used that fluorimetrically respond to the change in potential. Major component of all biological membranes; ~25% of total brain lipid is cholesterol. It is an essential structural component of mammalian cell membranes and is required to establish proper membrane permeability and fluidity. In addition to its importance within cells, cholesterol also serves as a precursor for the biosynthesis of steroid hormones, bile acids, and vitamin D. Cholesterol is the principal sterol synthesized by animals; in vertebrates it is formed predominantly in the liver. Small quantities are synthesized in other cellular organisms (eukaryotes) such as plants and fungi. It is almost completely absent among prokaryotes (i.e., bacteria).