Lipids
The bulk of the living matter is made up of Lipids, carbohydrates and proteins.
Lipids are water insoluble, but can be extracted with non-polar solvents like Benzene, methanol, or ether.
Some lipids act as storage molecules for example triglycerides stored in adipose tissue. Transport forms of lipids (Lipoproteins),are present in combination with proteins
Building blocks of lipids are fatty acids. Some lipids like cholesterol lack fatty acids but are potentially related to them. Lipids are constituents of cell membrane and act as hydrophobic barrier that permits the entry/exit of certain molecules. Lipids carry fat soluble vitamins and form special biomolecules. Lipid imbalance can lead to serious diseases like obesity and atherosclerosis. Break down of fatty acid produce energy, excessive breakdown cause ketosis, ketoacidosis, coma and death.
Cholesterol level in blood is controlled by several regulatory mechanisms. Such information is applied in the treatment of patients with high cholesterol levels.