lipids Flashcards
contrast saturated and unsaturated fatty acids
saturated:
- contain only single carbon bonds
- straight chain molecules and have many contact points
- higher melting point = solid at room temperature
- found in animal fats
unsaturated:
- contain double carbon (C=C) bonds
- ‘kinked’ molecules and have few contact points
- lower melting point = liquid at room temperature
- found in plant oils
how do triglycerides form? draw this
- condensation reaction takes place between 1 molecule of glycerol and 3 fatty acids which forms ester bonds
- (refer to images)
relate the structure of triglycerides to their functions
- high energy:mass ratio = high calorific value from oxidation so acts as an energy store
- insoluble hydrocarbon chain = no effect on water potential of cells and is used for waterproofing
- slow conductor of heat = thermal insulation (e.g. adipose tissue)
- less dense than water = buoyancy of aquatic animals
describe the structure and function of phospholipids
- amphipathic: glycerol backbone attached to 2 hydrophobic fatty acid tails and 1 hydrophilic polar phosphate head
- forms phospholipid bilayer in water = component of membranes
- tails can splay outwards = waterproofing e.g. for skin
are phospholipids and triglycerides polymers? explain your answer
no - they are not made from a small repeating unit; instead they are macromolecules
describe the structure and function of cholesterol
- steroid structure of 4 hydrocarbon rings
- hydrocarbon tail on one side, hydroxyl group (-OH) on the other side
- adds stability to cell surface phospholipid bilayer by connecting molecules and reducing fluidity