Lipids

Question 1

Lipids

Answer 1

Large group of organic molecules containing carbon, hydrogen and oxygen:

• Triglycerides
• Phospholipids
• Steroids
• Waxes

Question 2

Triglycerides

Answer 2

Structure:
Triglycerides are lipids made of one molecule of glycerol and three fatty acids joined by ester bonds formed in condensation reactions.

Function/Properties:

• Thermal insulation when stored under skin
• Energy storage as they yield twice as much energy as carbohydrates
• Physical protection around organs
• Buoyancy
• Source of metabolic water (water released in chemical reactions)

Question 3

(Mono/Poly) Unsaturated Fatty Acids

Answer 3

Structure:
-Contain at least one carbon-carbon double bond which causes a kink in the chain

Function/Properties:
-Liquid at room temperature

Mono-unsaturated fatty acids have one carbon-carbon double bond

Poly-unsaturated fatty acids have two or more carbon-carbon double bonds

Question 4

Saturated Fatty Acids

Answer 4

Structure:

• Contain only carbon-carbon single bonds
• Carbon atoms linked to the maximum number of hydrogen atoms
• Atoms tightly packed

Function/Processes:

• Solid at normal or body temperature
• Useful for energy storage

Question 5

Phospholipids

Answer 5

Structure:

• One molecule of glycerol, two fatty acids and one phosphate molecule
• Phosphate and glycerol make the “head”
• Two fatty acid molecules make the “tail”

Function/Properties:

• The more polar head is hydrophilic
• Non polar tail is hydrophobic

Question 6

Waxes

Answer 6

• Insoluble in water
• Prevent water loss
• Plants produce waxy cuticle on leaves to stop water loss

Question 7

Steroids

Answer 7

Structure:

• Ring structure
• Three 6 carbon atom rings and one 5 carbon atom ring

Function/Properties:

• Steroid sex hormones
• Cholesterol synthesis

Question 8

Saturated fat health implications

Answer 8

• Coronary heart disease caused by fatty deposits

- High fat intake increases low-density lipoprotein (LDL) cholesterol level which leads to atheroma deposition