1.3 LIPIDS

Question 1

What are triglycerides?

Answer 1

3 fatty acids + glycerol.

Question 2

What is the bond called that makes triglycerides?

Answer 2

An ester bond

Question 3

What do all triglycerides have in common?

Answer 3

They each have a glycerol group.

Question 4

Why do triglycerides have different properties?

Answer 4

They come from the R group on fatty acids before the condensation reaction.

Question 5

What do glycerol and fatty acids lose in a condensation reaction?

Answer 5

Fatty Acid (COOH): loses an OH group, left with C=O.
Glycerol (OH): loses an H+.
- Together they lose a water molecule.

Question 6

What are the functions of lipids?

Answer 6

• Energy source
• Waterproofing
• Insulation
• Protection
• Makes membranes

Question 7

What are solid lipids at RTP called?

Answer 7

Fats

Question 8

What are liquid lipids at RTP called?

Answer 8

Oils

Question 9

Are lipids soluble?

Answer 9

NO

Question 10

What do lipids dissolve in?

Answer 10

Organic solvents (ie Alcohols)

Question 11

What happens when you add lipids to water?

Answer 11

Nothing, as they are immiscible.

Question 12

How is the structure of a triglyceride adapted to its function?

Answer 12

• High C-H bond : C atoms ratio so good energy source.
• Low mass : energy ratio so good for storage (small mass with lots of energy)
• Insoluble, so good for storage.

Question 13

What is a phospholipid made up of?

Answer 13

• A glycerol backbone
• 2 fatty acid tails
• 1 phosphate group

Question 14

How are the monomers of a phospholipid arranged?

Answer 14

A hydrophilic phosphate head, with two hydrophobic fatty acid tails coming off it.

Question 15

What is the test for lipids called?

Answer 15

The emulsion test

Question 16

Outline the emulsion test

Answer 16

1. Take a grease free test tube and add 2cm³ of sample.
2. Add 5cm³ of ethanol.
3. Shake vigorously until everything has dissolved.
4. Add 5cm³ of water.
5. If you see a cloudy white emulsion, then a lipid is present.