Lipids? Fuel Storage and Building Material

These are fats and fat-like substances.
Composed of Carbon, Hydrogen and oxygen.

Most lipids are non-polar and therefore insoluble in water but readily dissolve in alcohol or ether.

Three principal groups of lipids:

• Neutral fats ? Triglycerides (protection, insulation, energy)
• Phospholipids (structural organisation, membranes)
• Steroids (biologically important molecules)
• Complex alcohols-structurally unlike fats but has fat-like properties.

TRIGLYCERIDES ? Natural fats

During hydrolysis the reverse happens and a single molecule of fat is broken down to 1 Molecule Glycerol and 3 Fatty Acids.

Most Triglyceride have 2 or 3 different fatty acids bonding to glycerol.

Saturated fats are those with no Carbon-to-Carbon double bonds within the fatty acid chain. These tend to be solids at room temperature.
Unsaturated fats contain 1 or more Carbon-to-Carbon double bonds.
Polyunsaturated fats contain 2 or more Carbon-to-Carbon double bonds. Typical examples are the plant oils, which tend to be liquids at room temperature.

PHOSPHOLIPIDS

Resemble Triglyceride structure but one of the fatty acid chains is replaced by phosphoric acid and nitrogen containing organic base.

	Often shown:

Eg: lecithin an important phospholipid of nerve membranes

Because the phosphate group is charged and polar and therefore hydrophilic and the remainder of the molecule is non-polar phospholipids can bridge 2 environments binding water-soluble molecules to water insoluble ones.

In H₂O gives globules.