Lipids

Question 1

What are the two types of lipids?

Answer 1

• Triglycerides
• Phospholipids

Question 2

Describe the structure of a fatty acid

Answer 2

• Variable R group/hydrocarbon chain
• Carboxyl group = -COOH

Question 3

What is the difference between an unsaturated and saturated fatty acid?

Answer 3

• Saturated - no carbon to carbon double bond, all carbons are fully saturated with hyrdrogen
• Unsaturated - has carbon to carbon double bond, so chain can kink

Question 4

How do triglycerides form?

Answer 4

• 1 glycerol molecule and 3 fatty acids
• Bonded by condensation reaction
• That forms 3 ester bonds
• And removes 3 water molecules

Question 5

Explain how the structure of triglycerides relate to its properties.

Answer 5

• Hight ratio of C-H bonds to carbon bonds - used in respiration for more energy release
• Hydrophobic/insoluble in water - no osmotic effect on the cell

Question 6

What is the difference between a triglyceride and a phospholipid?

Answer 6

• Triglyceride has 3 fatty acid chains
• Phospholipids have 2 fatty acid chains and a phosphate group connected to the glycerol

Question 7

How do the properties of a phospholipid relate to its structure?

Answer 7

• Forms the bilayer of a cell membrane, allows diffusion of non-polar/small molecules and restricts polar substances
• Phosphate group is hydrophilic - attracted to the water, points to the aqueous environment
• Fatty acids are hydrophobic - repelled by water, points to the interior of the membrane

Question 8

What is the test for lipids?

Answer 8

1. Add ethanol
2. Add water and shake
3. If lipids are present, milky white emulsion is produced