Lipids and Their Functions

Study Notes

Lipids are broad, non-polar organic chemical compounds with a greasy texture, poorly soluble in water, but soluble in organic solvents.
Lipids consist of carbon, hydrogen, and oxygen, and have plant and animal sources.
Functions of lipids:
- Long-term energy reserve
- Important in cell structure
- Acts as a thermal insulator for the body
- Acts as hormones

Lipids consist of a combination of one glycerol molecule with three fatty acids.
Glycerol is a trihydroxy alcohol considered the basis for the formation of fats.
Each glycerol molecule is linked to three fatty acids, forming esters, fats, or oils.

Saturated fatty acids:
- Have a long, continuous, unbranched hydrocarbon chain with single C-C bonds.
- Contain 16 or 18 carbon atoms.
- Are insoluble in water, but soluble in organic solvents.
- Are solid at room temperature.
Unsaturated fatty acids:
- Contain one or more double bonds, C=C.
- Are insoluble in water.
- Are necessary for the body, as their deficiency leads to skin diseases and a deficiency in some oxidizing enzymes.
- Are usually liquid at room temperature.

Simple fats:
- Result from the reaction of fatty acids with alcohols.
- Examples: fats and oils.
Complex fats:
- Consist of the reaction of fatty acids and any type of alcohol, to which carbohydrates, phosphorus, protein, and phosphorus are added.
- Examples: phospholipids.
Derived lipids:
- Derived from simple and complex fats through the process of hydrolysis.
- Examples: cholesterol.

Distinguish between saturated and unsaturated fatty acids using copper acetate.
Copper acetate reacts with saturated fatty acids to form copper salts (copper soap) in the form of a bluish-green precipitate.
Copper acetate reacts with unsaturated fatty acids to form green copper salts.

Decomposition of soap using hydrochloric acid (HCl) to liberate fatty acids.
Precipitation of soap using calcium chloride (CaCl2) to form insoluble calcium soap.
Separation of soap from solution using sodium chloride (NaCl) to cause the soap to float on the surface of the solution.