lipids Flashcards
describe the structure of a phospholipid
- 2 fatty acid tails
- glycerol
- phosphate head
describe the phosphate in a phospholipid
hydrophilic - attracts water
describe the fatty acid tails in a phospholipid
hydrophobic - repels water
how do phospholipids act as a barrier?
- part of cell surface membrane
- hydrophobic core is created when a phospholipid bilayer forms
- prevents water soluble substances getting through
how are lipids joined?
ester bonds
state 3 functions of phospholipids
- acts as a barrier
- holds proteins in membrane but allows some movement due to weak hydrophobic interactions
- separates external environment from aqueous cytoplasm
what does saturated mean?
no double bonds free
what does unsaturated mean
double bonds free
if the fatty acid tail is saturated, what does this mean for the membrane?
less fluid
describe the structure of a triglyceride
- 3 fatty acids
- glycerol
- ester bonds
- formed during condensation reactions
- insoluble
what happens when double bonds are present in fatty acids? (unsaturated)
- kinks occur
- causes chain to bend
- cannot pack closely and become liquid
state 4 roles of triglycerides
- energy source
- insulation
- buoyancy
- protection
how do triglycerides provide energy?
3 energy dense fatty acids are broken down via beta oxidation and the energy is released
how do triglycerides provide insulation?
they are hydrophobic, repelling water for aquatic animals
describe how an ester bond is formed
- hydroxyl groups on fatty acids and glycerol interact
- forming 3 water molecules (condensation reaction)
- process is esterification.
what is a sterol
- complex alcohol molecule
- with 4C ring structure
describe the structure of cholesterol
- hydroxyl group is attracted to phosphate heads
- carbon rings attracted to hydrophobic tails
- fits between phospholipids + prevents them aligning too closely & holds them together at the same time
what would happen to the pH of a solution when triglycerides are digested?
- the fatty acids are free from the ester bond
- so will lower the pH as they are acids
describe the function of cholesterol
helps strengthen cell membrane by interacting with the phospholipid bilayer and maintains fluidity
describe the difference between a phospholipid and a triglyceride
- tri contain 3 fatty acids, phos contain 2 fatty acids
- tri non-polar, phos have a polar head and non-polar fatty acid tails
