Lipids

Question 1

Elemental composition of lipids

Answer 1

Carbon, Hydrogen, Oxygen

Question 2

Examples of lipids

Answer 2

Triglycerides, phospholipids, steroids, waxes

Question 3

Are lipids polymers?

Answer 3

Not made from monomers

Question 4

Properties of lipids

Answer 4

Insoluble in water

Soluble in organic solvents

Question 5

Role of lipids

Answer 5

Energy source when oxidised, provides 2x the energy as same mass of carbohydrates
Waterproof plants and animals, waxy cuticles conserve water, oils secreted from sebaceous glands
Slow conductors of heat
Stored around delicate organs

Question 6

Formation of triglycerides

Answer 6

Condensation reaction between 1 glycerol and 3 fatty acids, water released
Ester bonds formed
Fatty acid formed from hydrocarbon chain and carboxyl
Glycerol made from hydroxyl groups

Question 7

Triglyceride variations

Answer 7

No double bonds=saturated
1 double bond=unsaturated
2 double bond=polyunsaturated

Question 8

Structure and properties of fats

Answer 8

Saturated triglycerides
Solid at room temp
Sit next to each other tightly

Question 9

Structure and properties of oils

Answer 9

Unsaturated triglycerides

Double bonds introduces kink in fatty acid structure, molecule cannot sit tightly together

Question 10

Phospholipid structure

Answer 10

1 fatty acid replaced by phosphate group
Polar molecule, phosphate is charged
Phosphate, hydrophilic head
Fatty acid, hydrophobic tail

Question 11

Lipid test

Emulsion test

Answer 11

Add ethanol to dissolve lipid sample

Add water to see white suspension of fat globules