Biological Molecules: Lipids Flashcards
What are the two groups of lipids?
triglycerides and phospholipids
what are triglycerides?
formed from the condensation reaction of 1 molecule of glycerol and 3 molecules of fatty acids
- ester bond forms between the glycerol and fatty acids
- removal of 3 water molecules
what bond is formed by the condensation reaction between a glycerol and fatty acid?
ester bond
what can the R group of a fatty acid be?
saturated or unsaturated
what are saturated fatty acids?
single bonds between adjacent carbon atoms in a hydrocarbon chain
what are unsaturated fatty acids?
double bond between adjacent carbon atoms in a hydrocarbon chain
what are phospholipids?
formed by the condensation reaction of 1 molecule of glycerol, 2 molecules of fatty acids and 1 molecules of a phosphate- containing group
what is a fatty acid(formula)?
RCOOH
what are properties of triglycerides?
- energy storage molecules
- insoluble in water, don’t affect the water potential of the cell and cause water to enter cell by osmosis(swell)
what are properties of phospholipids?
- make up the bilayer of cell membranes
- hydrophilic heads
- hydrophobic tails: centre of bilayer is hydrophobic so water soluble molecules cannot easily pass through
how do we test for lipids?
- emulsion test
- add ethanol
- shake
- add water
- milky white emulsion forms to show the presence of a lipid
what is the difference between the structure of a triglyceride and a phospholipid molecule?
in a phospholipid, one fatty acid is replaced by a phosphate
how do you test a piece of food to see if it has lipids?
- dissolve the food in ethanol, then shake and add water
- if lipids are present then a white milky emulsion would form
how do you find the percentage of lipid in plasma membrane by mass?
- divide mass of each lipid by the total mass of all lipids
- then multiply by 100
are triglycerides hydrophobic or hydrophilic?
hydrophobic
