Lipids

• Contains carbon, hydrogen and oxygen
• Non-polar
• Insoluble in water

Triglycerides formed by combinining 1 glycerol and 3 fatty acids in a condensation reaction

Ester bond is formed between the two molecules

Saturated Fatty Acids (usually in animals)

• No carbon-carbon double bonds
• Maximum number of hydrogens
• High intake can cause heart disease

Unsaturated Fatty Acids (usually in plants)

• Contains carbon-carbon double bonds
• Doesn't have maximum number of hydrogens

Forms plasma membrane

other roles:

• excellent energy reserve in plants and animals
• acts as insulator against heat loss when stored under skin
• provides protection for interal organs against damage
• triglycerides produce metabolic water when oxidised
• waterproof - waxy cuticle prevents water loss 

• contains 2 fatty acids and 1 phosphate group
• hydrophillic head / interacts with water / polar / phosphate and glycerol head
• hydrophobic tail / interacts with fat / non-polar / fatty acid tail