Lipid

Lipid

Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others. The main biological functions of lipids include energy storage, as structural components of cell membranes, and as important signaling molecules.

Lipids may be broadly defined as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks": ketoacyl and isoprene groups. Using this approach, lipids may be divided into eight categories: fatty acids, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, and polyketides (derived from condensation of ketoacyl subunits); and sterol lipids and prenol lipids (derived from condensation of isoprene subunits).

Although the term lipid is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides. Lipids also encompass molecules such as fatty acids and their derivatives (including tri-, di-, monoglycerides, and phospholipids), as well as other sterol-containing metabolites such as cholesterol. Although humans and other mammals use various biosynthetic pathways to both break down and synthesize lipids, some essential lipids cannot be made this way and must be obtained from the diet.

Read more about Lipid:  Metabolism, Nutrition and Health

Other articles related to "lipid, lipids":

Lipid Microdomain
... Lipid microdomains are formed when lipids undergo lateral phase separations yielding stable coexisting lamellar domains ... The question of whether such lipid microdomains observed in model lipid systems also exist in biomembranes had motivated considerable research efforts ... Lipid domains are not readily isolated and examined as unique species, in contrast to the examples of lateral heterogeneity ...
Lipid Bilayer Phase Behavior - Cholesterol
... The presence of cholesterol exerts a profound but complicated influence on lipid bilayer properties because of its unique physical characteristics ... Although it is a lipid, cholesterol bears little resemblance to a phospholipid ... has more recently been shown to be due to cholesterol intercalating between lipid molecules, filling in free space and decreasing the flexibility of surrounding lipid chains ...
Lipid - Nutrition and Health
... A few studies have suggested that total dietary fat intake is linked to an increased risk of obesity and diabetes ... However, a number of very large studies, including the Women's Health Initiative Dietary Modification Trial, an eight year study of 49,000 women, the Nurses' Health Study and the Health Professionals Follow-up Study, revealed no such links ...