lipids Flashcards
are lipids polymers?
no
lipids are macromolecules
what are lipids made up of?
fatty acids and glycerol
how are lipids joined?
ester bonds
structure of a triglyceride
- 3 fatty acids
- glycerol
- ester bond
- formed during condensation reactions
- insoluble
state 4 roles of triglycerides
- energy source
- insulation
- buoyancy
- protection
how do triglycerides provide energy?
when triglycerides oxidised during respiration causes carbon-hydrogen bonds to break, releasing energy
how do triglycerides provide insulation?
- compose part of myelin sheath
- compose part of adipose tissue layer
how do triglycerides provide buoyancy?
low density of fat tissues makes animals float easier
how do triglycerides provide protection?
adipose tissue contains stored triglycerides, protect organs from damage
saturated meaning
no carbon to carbon double bonds
how are chain tails in saturated fatty acids?
straight
if the fatty acid tail is saturated, what does this mean for the membrane?
less fluid
unsaturated meaning
carbon to carbon double bonds present
how are chain tails in unsaturated fatty acids?
kinks occur
if the fatty acid tail is unsaturated, what does this mean for the membrane?
more fluid
describe the structure of a phospholipid
- two fatty acid tails
- glycerol
- phosphate head
describe the phosphate in a phospholipid
hydrophilic
- attracted to water
describe the fatty acids in a phospholipid
hydrophobic
- repelled by water
how do phospholipids form a bilayer?
hydrophobic tails point towards centre of sheet
protected from water by hydrophobic heads
how do phospholipids act as a barrier?
- part of cell surface membrane
- separates aqueous environments
describe how an ester bond is formed
- esterification
- glycerol and 3 fatty acids undergo a condensation reaction
- 3 water molecules released
- bond forms between fatty acid carboxyl and glycerol hydroxyl
what is a sterol?
an alcohol with a hydroxyl group
describe the structure of cholesterol
- 4 carbon rings
- located between fatty acid phospholipid tails
- hydrophilic and hydrophobic regions
describe the function of cholesterol
- stabilises membrane structure
- maintains fluidity and temperature
- produce steroid hormones which pass through bilayer to reach receptors
state 4 biological roles of lipids
- membrane formation and creation of hydrophobic barriers
- hormone production
- electrical insulation
- waterproofing
