lipids

Question 1

are lipids polymers?

Answer 1

no
lipids are macromolecules

Question 2

what are lipids made up of?

Answer 2

fatty acids and glycerol

Question 3

how are lipids joined?

Answer 3

ester bonds

Question 4

structure of a triglyceride

Answer 4

• 3 fatty acids
• glycerol
• ester bond
• formed during condensation reactions
• insoluble

Question 5

state 4 roles of triglycerides

Answer 5

• energy source
• insulation
• buoyancy
• protection

Question 6

how do triglycerides provide energy?

Answer 6

when triglycerides oxidised during respiration causes carbon-hydrogen bonds to break, releasing energy

Question 7

how do triglycerides provide insulation?

Answer 7

• compose part of myelin sheath
• compose part of adipose tissue layer

Question 8

how do triglycerides provide buoyancy?

Answer 8

low density of fat tissues makes animals float easier

Question 9

how do triglycerides provide protection?

Answer 9

adipose tissue contains stored triglycerides, protect organs from damage

Question 10

saturated meaning

Answer 10

no carbon to carbon double bonds

Question 11

how are chain tails in saturated fatty acids?

Answer 11

straight

Question 12

if the fatty acid tail is saturated, what does this mean for the membrane?

Answer 12

less fluid

Question 13

unsaturated meaning

Answer 13

carbon to carbon double bonds present

Question 14

how are chain tails in unsaturated fatty acids?

Answer 14

kinks occur

Question 15

if the fatty acid tail is unsaturated, what does this mean for the membrane?

Answer 15

more fluid

Question 16

describe the structure of a phospholipid

Answer 16

• two fatty acid tails
• glycerol
• phosphate head

Question 17

describe the phosphate in a phospholipid

Answer 17

hydrophilic
- attracted to water

Question 18

describe the fatty acids in a phospholipid

Answer 18

hydrophobic
- repelled by water

Question 19

how do phospholipids form a bilayer?

Answer 19

hydrophobic tails point towards centre of sheet
protected from water by hydrophobic heads

Question 20

how do phospholipids act as a barrier?

Answer 20

• part of cell surface membrane
• separates aqueous environments

Question 21

describe how an ester bond is formed

Answer 21

• esterification
• glycerol and 3 fatty acids undergo a condensation reaction
• 3 water molecules released
• bond forms between fatty acid carboxyl and glycerol hydroxyl

Question 22

what is a sterol?

Answer 22

an alcohol with a hydroxyl group

Question 23

describe the structure of cholesterol

Answer 23

• 4 carbon rings
• located between fatty acid phospholipid tails
• hydrophilic and hydrophobic regions

Question 24

describe the function of cholesterol

Answer 24

• stabilises membrane structure
• maintains fluidity and temperature
• produce steroid hormones which pass through bilayer to reach receptors

Question 25

state 4 biological roles of lipids

Answer 25

• membrane formation and creation of hydrophobic barriers
• hormone production
• electrical insulation
• waterproofing