🩷 3.1.3 Lipids Flashcards
What are the two groups of lipids ?
Triglycerides and phospholipids
Which elements are present in a lipid?
Carbon
oxygen
hydrogen
What are some functions of lipids?
- insulation
- protection of organs
- phospholipids form the bilayer in the cell membrane
- energy store
What are triglycerides formed by ?
The condensation of one molecule of glycerol and three molecules of fatty acid
What does the condensation between glycerol and a fatty acid form?
An ester bond
What are the two things the R-group of a fatty acid can be ?
saturated or unsaturated
What is a saturated fatty acid?
a saturated bond is a single bond which is fully saturated with hydrogen
What is an unsaturated fatty acid?
A unsaturated bond is a double bond which is not fully saturated with hydrogen
Unsaturated fatty acids contain a double bond. What does this do to the triglyceride fatty acid chain?
It causes the fatty acid chain to kink. This lowers the melting point of the triglyceride.
What is the chemical formula for a fatty acid?
R-COOH
What are phospholipids formed from?
The condensation of one molecule of glycerol, 2 fatty acids and a phosphate containing group
Triglycerides are hydrophobic. what does this mean?
This means that they wont mix in water. This is due to there hydrophobic fatty acid tails, making them insoluble.
Phospholipids are hydrophillic and hydrophobic. What does hydrophillic mean ?
This means that they can mix in water .
which part of a phospholipid is hydophillic and what does it form in water?
The phosphate head is hydrophillic and it forms a bilayer in water.
What are the differences between phospholipids and triglycerides?
- phospholipids have 2 fatty acid chains but triglycerides have 3
- Phospholipids have a phosphate group instead of the third fatty acid whereas triglycerides don’t
What are the similarities between phospholipids and triglycerides?
- Both have a glycerol backbone
- Both have fatty acid chains
- Both have ester bonds
What is one function related to a triglycerides structure?
Triglycerides store lots of energy in there fatty acid hydrocarbon tails. When broken down they release this energy.
Another structural property is that triglycerides are insoluble. What does this mean functionally?
This means that the cells water potential is not affected. This is important as if they didn’t repel water, it would cause the cell to swell up.
What are phospholipids a main component of ?
They are a main component in cell membranes and they control what goes in and out of a cell.
what is the emulsion test for lipids?
1- add ethanol to sample and shake
2- add water
3- a positive result is a white emulsion
