Lipids Flashcards
What is the structure of a triglyceride? How does this relate to their function?
STRUCTURE
-Made up of 3 fatty acids and 1 glycerol, all joined together via an ester bond with glycerol.
-The fatty acids have different hydrocarbon chains. If a hydrocarbon chain contains a carbon-to-carbon double covalent bond that it is described as unsaturated (Can be ‘mono- or ‘poly-‘), if not, then it is described as saturated.
PROPERTIES
-Triglycerides can store a significant amount of energy (Due to a high ratio of energy-storing carbon-hydrogen bonds)
-Triglycerides have a low mass to energy ratio, meaning not many can be stored whilst still yielding a high amount of energy.
-Insoluble in water therefore do not affect water potential.
-Release water when oxidised, making them an important source of water for organisms in dry deserts.
What are the roles of lipids?
1) Source of energy (Provide more than twice the energy as the same mass of carbohydrate)
2) Waterproofing (Lipids are insoluble in water and are therefore useful as a waterproofing)
3) Insulation (Fats are slow conductors of heat and also insulate nerve cells in the myelin sheath)
4) Protection (Often is stored around delicate organs, such as the kidney)
What is the structure of a phospholipid? How does this relate to their function?
STRUCTURE
-1 glycerol, 1 phosphate molecule, 2 fatty acids.
-Hydrophilic head (Attraccted to water but not to fat)
-Hydrophobic tail (Oriented away from water but mixes readily with fat)
-Polar
PROPERTIES
-Phospholipid bilayer around cells acts as a barrier.
-Glycolipids can be formed from them, which are essential in cell recognition.
What is the test for lipids?
- Add 2cm^3 of the sample being tested to a test tube, and then add 5cm^3 of ethanol to it.
- Shake the tube thoroughly to dissolve any lipid in the sample.
- Add 5cm^3 of water and shake gently.
- A milky-white emulsion indicates the presence fo a lipid.
- Repeat the procedures using water instead of the sample; the final solution should r clear.
