Lipid

Lipids are fats, i.e. hydrophobic or amphipathic molecules (one hydrophobic part and one hydrophilic part).

Features of lipids

Lipids are characterised by the fact that they are insoluble in water and, conversely, are soluble in non-polar organic solvents.

Diversity of lipids

There are eight varieties of lipids according to the UPAC classification:

• fatty acids (including omega-3);
• acylglycerols (or glycerides, including triglycerides) ;
• phosphoacylglycerols (or phosphoglycerides;
• sphingolipids ;
• sterols (including cholesterol) ;
• prenols;
• polyketides ;
• saccharolipids (or glycolipids).

Role of lipids

Waxes and vegetable oils are formed from lipids. Lipids in the diet provide the largest number of calories (9.3 kilocalories per gram).

Lipids carry out a wide range of biological functions including:

• energy production mainly by βoxidation ;
• transmission of hormone messages (estrogen, testosterone) ;
• they play a key role in the cell as constituants of the cell membrane lipid bilayer.