2.1.2 Biological Molecules - Lipids

Question 1

What are the three types of lipids?

Answer 1

1. Triglycerides
2. Phospholipids
3. Sterols

Question 2

What does a triglyceride contain?

Answer 2

contains 1 glycerol and 3 fatty acids

Question 3

Fatty acids are …

Answer 3

hydrophobic. This makes lipids insoluble in water.

Question 4

What type of bond forms when a glycerol molecule and a fatty acid join together? and what is the process/reaction called?

Answer 4

An ester bond is formed between the glycerol molecule and the fatty acids, and water is formed as a product.
The process/reaction is called esterification.

Question 5

Fatty acids: saturated or unsaturated?

Answer 5

Saturated - no double bonds

Unsaturated - has double bond, this causes kinks in the chain which changes the structure causing it to be less compact.

Question 6

What does a phospholipid contain?

Answer 6

Contains a glycerol, 2 fatty acids, and a phosphate group.

Question 7

The phosphate group is …

Answer 7

hydrophilic

Question 8

Glycerol

Answer 8

is a member of a group of molecules called alcohol (-OH)

Question 9

Fatty acids

Answer 9

belong to a group of molecules called carboxylic acids - they consist of a carboxyl group (-COOH).

Question 10

An example of a sterol

Answer 10

Cholesterol

Question 11

Cholesterol contains …

Answer 11

a hydroxyl group (-OH), which attracts water. (allows condensation/esterification to occur)

Question 12

What are the functions of Cholesterol?

Answer 12

1. produce hormones e.g. oestrogen, testosterone, (as well as Vitamin A + D)
2. brings rigidity and stability to the structure in a phospholipid bilayer

Question 13

What is the role of lipids?

Answer 13

• maintaining the bilayer
• waterproofing
• electrical insulation –> around the axons for impulse transmission
• hormone production

Question 14

What is the role of fats?

Answer 14

• buoyancy
• insulation
• energy storage
• packing and protection