1.3: Lipids

Question 1

Structure of triglyceride

Answer 1

Condensation reaction between one glycerol and three fatty acids joined by ester bonds

Question 2

What is a saturated fatty acid?

Answer 2

Only single bonds between carbons in hydrocarbon chains

Question 3

What is a unsaturated fatty acid?

Answer 3

hydrocarbon chain has at leat one double bond between carbons

Question 4

State and explain properties of triglycerides.

Answer 4

1) energy storage - large ratio of energy storing carbon-hydrogen bonds compared to the number of carbon atoms

2) Metabolic water source - High ratio of hydrogen to oxygen atoms. Can release water of oxidised

3) Insoluble - doesn’t affect water potential, large and hydrophobic

4) Relatively low mass so a lot can be stored without increasing mass and preventing movement

Question 5

What is the test for lipids

Answer 5

Mix with ethanol and shake. Add water and shake forms a white emulsion.

Question 5

What is the structure of a phospholipid?

Answer 5

Made of a glycerol, two fatty acids and a phosphate joins by a condensation reaction by ester bonds

Question 6

How does a phospholipid form a bilayer? (3)

Answer 6

• Phosphate group is negatively charged, polar. Fatty acids have no charge, non-polar
• Phospholipid head hydrophilic. Fatty acid tail is hydrophobic
• Hydrophobic fatty acid tails face away from each other and hydrophilic heads face the water.