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3.2.2.1.2. Cerides

Cerides or waxes

The waxes are lipids that are obtained by esterification of one fatty acid long chain (14 to 36 carbon atoms) with a monoalcohol, also long chain (16 to 30 atoms carbon).

The result is a completely apolar molecule, very hydrophobic, since no charge appears and its structure is of considerable size.

This characteristic allows the typical function of waxes to consist of serving as a waterproofing agent. The coating of young leaves, fruits, flowers or thalli, as well as the integuments of many animals, hair or feathers is covered with a waxy layer to prevent the loss or entry (in small animals) of water.

They can also appear mixed with free fatty acids and steroids, as in beeswax, spermaceti from whales, lanolin or protective wool wax, earwax from the ear canal, etc.

Fundamental ideas about waxes

The cerides (waxes) and triglycerides (fats) are simple lipids formed by esterification of the carboxylic groups (-COOH) of fatty acids with hydroxyl groups (-OH) of an alcohol:

  • The acylglycerides are formed by esterification of 1, 2 or 3 molecules of fatty acids with glycerine. They have an energy reserve function, mainly.
  • Cerides are formed by the esterification of a fatty acid molecule and a long-chain monovalent alcohol. They have a protective and waterproofing function.


         

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Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.