313 Lipids

Question 1

What are the roles of lipids? (4)

Answer 1

• Source of energy
• Waterproofing
• Insulation
• Protection

Question 2

What are the components of a Triglyceride?

Answer 2

One glycerol molecule and 3 fatty acids bonded with ester bonds.

Question 3

How is the structure of triglycerides related to their properties? (think about camels and fat people)

Answer 3

• High ratio of energy - storing C-H bonds so it’s an excellent energy store
• Non-polar - insoluble in water, does not affect osmosis
• high ratio of H to O atoms - release water when oxidised to provide a source of water

Question 4

What does a saturated fatty acid have?

Answer 4

Single bond between carbons.

Question 5

What does an unsaturated fatty acid have? What is it’s effect.

Answer 5

Some double bonds between carbon atoms. (Limits the number of H atoms bonded.)

Question 6

Why do oil contain unsaturated triglycerides rather than saturated?

Answer 6

Unsaturated fatty acids cause molecules to bend, making them less tightly packed, resulting in more fluid structures.

Question 7

Which two words means that there are either one c-c double bond or more than one c-c double bond?

Answer 7

Monounsaturated
Polyunsaturated

Question 8

Describe the structure of phospholipids.

Answer 8

Hydrophobic tail (2 fatty acids)
Hydrophilic head (1 phosphate group, 1 glycerol)

Question 9

What type of molecule is Phospholipids?

Answer 9

Polar molecule.

Question 10

Describe the test for lipids. (Emulsion test)

Answer 10

Add ethanol, add water, shake, if white emulsion, lipid is present.