1. Biological Molecules - Lipids Flashcards
Name 4 features of all lipids:
-Contain C, H, O
-Proportion of oxygen to carbon and hydrogen is smaller than in carbohydrates
-Insoluble in water
-Soluble in organic solvents such as alcohols
What are the 5 main roles of lipids?
-Cell membranes
-Source of energy
-Waterproofing
-Insulation
-Protection
What do phospholipids contribute to cell membranes?
They contribute to the flexibility of membranes and the transfer of lipid-soluble substances across them.
Compare the amount of energy in lipids to carbohydrates:
When oxidised, lipids provide more than twice the energy as the same mass of carbohydrate and release valuable water.
How do lipids help waterproofing in plants and insects?
Both plants and insects have waxy lipid cuticles that conserve water.
How do lipids help waterproofing in mammals?
They produce an oily secretion from sebaceous glands in the skin.
In which two ways do lipids help with insulation?
Both thermally and electrically (in myelin sheath around nerve cells).
What are triglycerides?
Three fatty acids combined with a glycerol molecule.
What kind of reaction is used to join the glycerol molecule with the fatty acids?
A condensation reaction.
What bond is formed between a glycerol and fatty acid molecule?
An ester bond.
How many different fatty acids are there?
Over 70
What is the difference between a phospholipid and triglyceride?
Phospholipids are very similar to triglycerides except that one of the fatty acid molecules is replaced by a phosphate molecule.
What is the difference between a fatty acid molecule and a phosphate molecule?
Fatty acid molecules are hydrophobic, phosphate molecules are hydrophilic.
What two parts are a phospholipid made up of?
A hydrophilic ‘head’ and a hydrophobic ‘tail’
What are molecules that have two ends that behave differently said to be?
Polar
