Lipids Flashcards
1
Q
What are 2 groups of lipids?
A
- triglycerides
- phospholipids
2
Q
Describe how a triglyceride is formed.
A
- 1 glycerol molecule combines w 3 fatty acid molecules, via condensation reactions
3
Q
What type of bond is formed from the condensation reaction between glycerol + a fatty acid (RCOOH)?
A
- ester bond
4
Q
What are the 2 types of R-group a fatty acid can have?
A
- saturated: hydrocarbon chain has only single bonds between Cs
- unsaturated: hydrocarbon chain has at least 1 double bond between Cs, causing chain to kink (bend)
5
Q
Describe how the structure of triglycerides relate to its diff properties.
A
- large ratio of energy storing C-H bonds, compared to NO° of C atoms, allows it to store lots of energy in molecule
- high ratio of H to O atoms allows it to act as a metabolic water source bc can release water if oxidised (essential for desert animals)
- large + hydrophobic makes them insoluble so doesn’t affect water potential + osmosis
- lipids have a relatively low mass so lots can be stored w/o inc. mass + preventing movement
6
Q
Describe the structure of a phospholipid.
A
- hydrophobic, polar head: 1 phosphate group attached to a glycerol molecule via a phosphoester bond
- hydrophilic, non-polar tails: 2 fatty acid chains attached to a glycerol molecule by ester bonds, formed via condensation reactions
7
Q
Describe how the structure of phospholipids relate to its diff properties.
A
- hydrophilic head is charged so can attract water, but repels other fats
- hydrophobic tails aren’t charged so repels water, but will mix w fats
- in water hydrophilic heads face outwards so are exposed to water + hydrophobic tails face inwards
- form a phospholipid bilayer membrane structure which makes up plasma membrane around cells
8
Q
Describe the biochemical test for lipids.
A
- dissolve sample in ethanol
- then add distilled water
- if lipids are present, a white emulsion will appear
