3.1.3 Lipids - Triglycerides, Phospholipids and the Emulsion Test Flashcards
Which 3 elements do lipids contain?
Carbon
Hydrogen
Oxygen
Which part of a phospholipid is hydrophilic?
The phosphate ‘head’
Identify the molecule

Polyunsaturated fatty acid

What does hydrophobic mean?
water hating
How does the structure of triglycerides relate to their properties?
- High ratio of carbon-hydrogen bonds make them an excellent energy source
- Low mass to energy ratio- animals don’t have to carry a heavy energy store around.
- Non-polar molecules are insoluble in water so they do not affect osmosis in cells.
- High ratio of hydrogen to oxygen atoms so water released when trigylcerides are oxidised. Good for animals in deserts.
Identify the molecule

Monounsaturated fatty acid

Identify the molecule

Phosphate molecule

What state do monounsaturated and polyunsaturated fats take at room temperature?
Liquid - they are oils.
What is mean by a saturated fatty acid?
A fatty acid that contains no double bonds between the carbon atoms
Identify the molecule

Glycerol

Phospholipids are p___________ molecules
polar
What does the following describe:
- Add 2cm3 of food and add to a test tube.
- Add 5 cm3 of ethanol
- Shake the tube thoroughly to dissolve any lipid.
- Add 5cm3 of water and shake gently
- A cloudy-white colour indicates a positive result.
The emulsion test for lipids
What state do saturated lipids take at room temperature?
Solid - they are fats
What is meant by a polyunsaturated fatty acid?
A fatty acid that contains more than 1 double bond between its carbon atoms.
What does hydrophilic mean?
attracted to water
What type of bond forms between glycerol and fatty acid molecules?
Ester bond