Lipids Flashcards
2 types of lipid
Triglycerides and phospholipids
How are triglycerides formed?
Via the condensation reactions between one molecule of glycerol and three molecules of fatty acids. Ester bonds are formed
Saturated fatty acids
The hydrocarbon chain has only single bonds between carbons
Unsaturated fatty acids
The hydrocarbon chains consist of at least one double bond between carbons
Properties of Triglycerides
- Due to the large ratio of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms; a lot of energy is stored in the molecule
- Due to the high ratio of hydrogen to oxygen atoms they act a metabolic water source. Triglycerides can release water if they are oxidised. This is essential for animals in the desert.
- Triglycerides do not affect water potentials and osmosis. This is because they are large and hydrophobic, making them insoluble in water
- Lipids have a relatively low mass. Therefore a lot can be stored without increasing mass and preventing movement.
What are phospholipids made of?
A glycerol molecule, two fatty acids chains and a phosphate group(attached to the glycerol).
How are phospholipids made?
The two fatty acids also bond to the glycerol via two condensation reactions, resulting in two ester bonds
The ‘head’ of a phosolipid
It’s hydrophillic so can attract water as it is charged. Due to the phosphate being charged(polar), it repels other fats.
The ‘tail’ of phospholipids
The fatty acid chain is not charged(non-polar). It is known as the hydrophobic ‘tail’ and it repels water but will mix with fats
Around cells
Phospholipids have two charged regions, so they are polar.
In water they are positioned so that the heads are exposed to water and the tails are not.
This forms a phospholipid bilayer which makes up the plasma membrane around cells
