triglyceride

Triglyceride (or triacylgrlycerol) is a glyceride in which the glycerol is esterified with three fatty acids. It is the main constituent of vegetable oil and animal fats.

Energy storage

Triacylglycerols, stored in adipose tissue, are a major form of energy storage in animals. Animals use triglycerides for energy storage because of its high caloric content (9 KCal/g), whereas plants, which do not require energy for movement, can afford to store food for energy in a less compact but more easily accessible form, such as starch (carbohydrate).

Triglycerides and phospholipids are broken down into free fatty acids by the action of lipases.

Beta oxidation is the process by which fatty acids, in the form of acyl-CoA molecules, are broken down in the mitochondria and/or in peroxisomes to generate acetyl-CoA.

The acetyl CoA is then ultimately converted into ATP, CO2, and H2O using the citric acid cycle and the electron transport chain.

Conversely, fatty acid biosynthesis (lipogenesis) takes place in the cytoplasm, using acetyl-CoA (derived from carbohydrates, amino acids or fatty acids) as the precursor.

The fatty acids may be subsequently converted to triacylglycerols that are packaged in lipoproteins (VLDL’s) and secreted from the liver.

See also

 Lipids

• glycerids