12.1 Lipids

Question 1

what are lipids

Answer 1

fats and oils

Question 2

properties of fats

Answer 2

solid (rt)
saturated - animals
insoluble - dont mix
immiscible - dont mix in water
dissolve in organic solvents - ethanol

Question 3

properties of oils

Answer 3

liquid (rt)
unsaturated - plants

Question 4

2 types of Lipids

Answer 4

Triglycerides and phospholipids

Question 5

what are triglycerides commonly found in

Answer 5

• food - storage molecules
• conduct heat slowly -> good thermal and electrical insulators (neurones)

Question 6

what do phospholipids do

Answer 6

• help to form the cell membrane of a cell
• stored around delicate organs - kidneys - to protect them

Question 7

what are triglycerides made up of

Answer 7

1 glycerol molecule and 3 fatty acids joined by ester bonds (condensation)
‘glycerol head’ and ‘fatty acid tails’

Question 8

why are triglycerides not polymers

Answer 8

they arent made up of the same / similar monomers

Question 9

formula for a triglyceride

Answer 9

CH3(CH2)nCOOH where n is 12 - 22 c atoms

Question 10

what 3 things happen when a glycerol molecule condenses with 3 fatty acids

Answer 10

3
esters bonds formed
condensation reactions occur
water molecules are released

Question 11

saturated meaning

Answer 11

• do not have double bonds between the carbon atoms within the hydrocarbon chain
• single carbon to carbon bonds
• fatty acids packed closely together with the maximum number of hydrogen atoms

Question 12

unsaturated meaning

Answer 12

• have double bonds between the carbon atoms within the hydrocarbon chain
• kink - bend - is formed

Question 13

3 factors of triglycerides

Answer 13

• low mass to energy ratio
• insoluble
• high H to O ratio

Question 14

how does having a low mass to energy ratio affect triglycerides

Answer 14

makes them a good store of energy

Question 15

how does being insoluble affect triglycerides

Answer 15

storing them doesnt affect the water potential

Question 16

how does having a high H to O ratio affect triglycerides

Answer 16

they are a good source of water when broken down

Question 17

emulsion test for lipids

Answer 17

• small amount of sample placed in a test tube with 2cm3 of ethanol
• shake - fat dissolves in the alcohol
• water added drop by drop and shaken again
• positive a cloudy white emulsion

Question 18

what are phospholipids made up of

Answer 18

1 glycerol molecule combined to 1 phosphate group and 2 fatty acids

Question 19

the phosphate group (formula and charge)

Answer 19

formula PO43- and has a negative charge - polar

Question 20

the fatty acid tails (charge and polar or non-polar)

Answer 20

have no charge, they are non-polar

Question 21

phospho-glycerol head

Answer 21

hydrophilic - attracts water - soluble
face the water

Question 22

fatty acid tails

Answer 22

hydrophobic - repels water - not soluble
face each other

Question 23

what do phospholipids form in water

Answer 23

a bilayer

Question 24

what does a phospholipid bilayer form

Answer 24

the basis of the cell membrane