3.5 Lipids

Question 1

what are lipids made up of

Answer 1

CHO (non-polar)

Question 2

triglycerides

Answer 2

one glycerol + 3 fatty acids

Question 3

esterification

Answer 3

• hydroxyl groups from both elements interact to form 3 H2O molecules and form ester bonds
• condensation reaction
• broken by hydrolysis and addition of 3 H2O molecules

Question 4

saturated fatty acids

Answer 4

• no double bonds

- can pack closely together

Question 5

unsaturated fatty acids

Answer 5

• double bonds present
• cause bending so can’t pack together
• liquid at room temperature

Question 6

phospholipids

Answer 6

made up of CHO+phosphorus

head =hydrophobic
tail =hydrophilic

Question 7

role of phospholipids

Answer 7

called surfactants = layer on water surface

form cell membranes due to bilayer arrangement

Question 8

sterols

Answer 8

complex alcohol molecules based on a 4 carbon ring structure with OH group at one end

hydroxyl group = polar = hydrophilic
rest of molecule = non-polar = hydrophobic

Question 9

cholesterol

Answer 9

• role in formation of cell membranes
• made in liver + intestines
• stabilises cell membranes and regulates fluidity

Question 10

what can cholesterol be used to manufacture

Answer 10

• vit D
• steroids
• bile

Question 11

roles of lipids (4)

Answer 11

• membrane formation + creating hydrophobic barriers
• hormone production
• electrical insulation (impulse transmission)
• waterproofing

Question 12

lipids stored under skin and around organs provide… (3)

Answer 12

• thermal insulation to stop heat loss
• cushioning to protect organs
• buoyancy for aquatic organs

Question 13

what test is used to identify of lipids

Answer 13

emulsion test

1. mix sample with ethanol
2. mix with water and shake
3. if white emulsion forms as layer on top = lipid present