Lipid
Most common lipid is the triglyceride in a form of fats and oils. Fats are solid in room temperature, oils are liquid.
Triglycerides are three fatty acid molecules with a glycerol molecule. They have a -COOH tail, and glycerol is an alcohol.
Triglycerides are three fatty acid molecules with a glycerol molecule. They have a -COOH tail, and glycerol is an alcohol.
The fatty acid bonds with glycerol by condensation. This is shown by the C-O-C bond in Figure 1.1. When fatty acids combine with glycerol, it becomes a glyceride. Since there are three tails, they are named 'triglyceride'.
They are insoluble in water, but soluble in certain solvents. This is due to their hydrocarbon tails and fatty acids. The fatty acids have no uneven distribution of electrical charge and therefore does not bond with water which makes them insoluble with water.
This means that they are non-polar and hydrophobic.
They are insoluble in water, but soluble in certain solvents. This is due to their hydrocarbon tails and fatty acids. The fatty acids have no uneven distribution of electrical charge and therefore does not bond with water which makes them insoluble with water.
This means that they are non-polar and hydrophobic.
Saturated and unsaturated fatty acids and lipids
Unsaturated fatty acids have double bonds in them. They make lipids melt easily.
More double bonds will give them the classification of polyunsaturated.
If there is only one, it is monounsaturated.
More double bonds will give them the classification of polyunsaturated.
If there is only one, it is monounsaturated.
Role of triglycerides
Lipids are excellent energy reserve because of the greater amount of carbon-hydrogen bonds than carbohydrates.
When the same mass of lipid and carbohydrate is oxidated, the lipid will yield more energy compared to carbohydrates.
Fat is also an insulator to prevent loss of heat, and is a metabolic source of water for organisms in dry places.
When the same mass of lipid and carbohydrate is oxidated, the lipid will yield more energy compared to carbohydrates.
Fat is also an insulator to prevent loss of heat, and is a metabolic source of water for organisms in dry places.
Phospholipids
A lipid that has a hydrophillic head and two hydrophobic fatty acids.
One phosphate group replaces one fatty acid.
This phosphate group is polar and is able to dissolve in water.
One phosphate group replaces one fatty acid.
This phosphate group is polar and is able to dissolve in water.
Testing for Lipids
- Mix ethanol with substance and shake.
- Move the solution to another tube.
- Result should be cloudy white.
This is because the lipid molecules does not allow the ethanol to mix with water.
This creates a barrier for light - it reflects and scatters light, making the mixture cloudy white.