triglycerides & fatty acids

What is the role of lipids?

• Energy store

• Part of cell membranes

• Insulation

• Protection e.g waxy cuticle on leaves

• Steroid hormones

What are lipids?

Fats and oils

Two groups of lipids?

• Triglycerides

• Phospholipids

Formation of triglyceride

Fatty acid formula?

CH3(CH2)nCOOH

Structure of glycerol

Diagram of a triglyceride forming

What are fatty acids?

Long chain of carbons and hydrogens with a carboxyl group at one end

What are saturated fatty acids?

The hydrocarbon chain has only single bonds

What are unsaturated fatty acids?

The hydrocarbon chain consists of at least one double bond

• Causes kinks in the chain

How are triglycerides formed?

• Condensation reaction

• One molecule of glycerol and 3 molecules of fatty acids

• Forms ester bonds (covalent bonds)

• Water is released

Are triglycerides hydrophobic or hydrophylic?

Hydrophobic - makes them insoluble in water

Role of triglycerides?

Energy storage

• Hydrocarbon tails contain lots of chemical energy (2x carbohydrates)

What changes when triglycerides are formed and where does it occur?

• Fatty acids change - glycerol stays the same

• Occurs between carboxyl group (COOH) of fatty acid and hydroxyl groups (OH) of glycerol

How does triglycerides structure make them a good energy storage molecule?

Insoluble in water - doesn’t affect water potential

Low mass for amount of energy stored - high energy density