Unit 1 Biological Molecules - Lipids

Question 1

What are the 2 types of lipids

Answer 1

• Triglycerides

- Phospholipids

Question 2

Describe how the 2 types of lipids are formed

Answer 2

Triglycerides 
- Formed by condensation of
1 GLYCEROL MOLECULE & 3 FATTY ACIDS
- Joined by ester bonds & 3 waters released
Phospholipids
- Formed by condensation of
1 GLYCEROL MOLECULE BACKBONE & 
2 HYDROPHOBIC FATTY ACID TAILS
Joined by ester bonds

&= 1 HYDROPHILLIC PHOSPHATE HEAD formed by phosphodiester bond NOT ESTER & NOT CONDENSATION

Question 3

Describe the difference between saturated and unsaturated fatty acid chains.

Answer 3

BOTH CAN BE SATURATED/UNSATURATED
Saturated
- Only contains single C=C bonds between carbon atoms
- Higher melting points
Unsaturated
- Contains 1 or more C=C bonds between carbon atoms
- Lower melting points

Question 4

Describe the bond formed between glycerol and a fatty acid.

Answer 4

Ester bond

R-COOH

Question 5

Relate 2 properties of triglycerides to their function.

Answer 5

= High energy : mass ratio

= Metabolic water source - release water

Question 6

Relate 2 properties of triglycerides to their function.

- Low mass

Answer 6

Insoluble as large and hydrophobic(water repelling)
= Doesn’t affect water potential
Slow conductor of heat
= Thermal insulation

Question 7

Relate the structure of phospholpids to their function.

Answer 7

Glycerol backbone attached to

• 2 hydrophobic(repel) fatty acid tails and
• 1 hydrophilic(attract) phosphate head

= Forms phospholipid bilayer in water - head exposed to water and tails are not
= Forms bilayer of cell membrane structure

Question 8

Are phospholipds and triglycerides polymers?

Answer 8

No they are macromolecules