Lipids

Question 1

Definition of glycerol

Answer 1

A molecule made up of 3 carbons, 3 hydroxyl groups and 5 hydrogen’s
C3H8O3

Question 2

Definition of fatty acid

Answer 2

A molecule that contains a hydrocarbon (Alkane) chain and an acid (COOH group)

Question 3

What letter can the hydrocarbon chain be denoted as?

Answer 3

R

Question 4

How many fatty acids attach to 1 glycerol?

Answer 4

3

Question 5

How many water molecules are made when 1 lipid is made?

Answer 5

3

Question 6

5 uses of lipids

Answer 6

Membranes are lipids
Respiration - release more energy than the same amount of carbohydrate
Insulation
Some hormones are lipids eg oestrogen and testosterone
Protection around organs eg kidneys

Question 7

3 lipids I need to know

Answer 7

Triglyceride
Phospholipid
Cholesterol

Question 8

What bond is in lipids?

Answer 8

Ester bond

Question 9

Structure of triglyceride

Answer 9

3 fatty acids and 1 glycerol

Question 10

Structure of phospholipid

Answer 10

2 fatty acids 1 glycerol and 1 phosphate group

Question 11

Structure of cholesterol

Answer 11

Hydrocarbon ring attached to a hydrocarbon tail

Ring has polar hydroxyl groups attached to it

Question 12

Properties of triglyceride

Answer 12

Insoluble
Long tail, lots of bond to break/energy to release
Can be saturated, monounsaturated and polyunsaturated

Question 13

Properties of phospholipid

Answer 13

Centre of bilayer is hydrophobic so water soluble substances can’t easily pass through.
Hydrophilic head attracted to water

Question 14

Properties of cholesterol

Answer 14

Not very soluble
Small/ flattened shape so can fit between phospholipid molecules
Bond to phospholipid tails.

Question 15

Role of triglyceride

Answer 15

Energy storage (release twice as much energy as the same amount of carbohydrate)
Insoluble so doesn't affect water potential

Question 16

Role of phospholipid

Answer 16

Form cell membrane
Stop water soluble substances passing through easily
Maintains stable intracellular environment

Question 17

Role of cholesterol

Answer 17

Stabilise/strengthens cell membrane
Prevent it from becoming to fluid/too solid.
Maintains membranes permeability

Question 18

Why are triglycerides and phospholipids macromolecules but not polymers?

Answer 18

They are large, complex molecules but are not made from repeating units/monomers.

Question 19

Why do some triglycerides not form solids at room temperature?

Answer 19

Fatty acids with single C-C bonds are saturated while double/many bonds between carbons are unsaturated.
Double bonds cause fatty acids to bend so they are less compact and therefore do not solidify at room temperature.