Lipids Flashcards
Give two examples of lipid
- Triglycerides
- Phospholipids
What is the structure of a triglyceride?
One molecule of glycerol with three fatty acids attached to it
Explain the structure of the fatty acid tail on a triglyceride
They have tails made of hydrocarbons which are hydrophobic. These tails make lipids insoluble in water
How is a triglyceride formed?
A condensation reaction joins a fatty acid to a glycerol molecule, an ester bond forms and a molecule of water is released. This happens three times
Fatty acids can be what?
- Saturated
- Unsaturated
What is the difference between a saturated fatty acid and an unsaturated fatty acid?
Saturated fatty acids don’t have any double bonds between their carbon atoms. Unsaturated fatty acids have at least one double bond between carbon atoms, which cause the chain to kink
Where are phospholipids found?
In the cell membrane
What is the structure of a phospholipid?
A molecule of glycerol, two fatty acids and a phosphate group. The phosphate group is hydrophilic and the fatty acid tails are hydrophobic
How is the structure of a triglyceride related to its function?
- Hydrocarbon tails of fatty acids contain lots of chemical energy - energy is released when broken down
- Insoluble so they don’t affect the water potential of the cell and cause water to enter the cell via osmosis. Clump to form insoluble droplets - tails in heads out
How is the structure of a phospholipid related to its function?
Head are hydrophilic, tails hydrophobic - form double layer, heads out tails in. The centre is hydrophobic so water-soluble substances can’t easily pass through
Explain the emulsion test for lipids
Shake the test substance with ethanol for about minute so it dissolves, then pour the solution into water. Any lipid will show as a milky emulsion
