BM: Lipids Flashcards
Name two types of lipids:
- Triglycerides
- Phospholipids
What characteristics do all lipids share?
- Contain hydrogen, carbon and oxygen
- Proportion of oxygen to carbon and hydrogen is smaller than in carbohydrates
- Insoluble in water
- Soluble in organic substances like alcohols and acetone
What are triglycerides made of?
One molecule of glycerol and three fatty acid tails.
Draw the structure of a triglyceride:
Describe the structure of fatty acid molecules.
How does this relate to the characteristics of a lipid?
Molecules have tails made of hydrocarbons.
Basic structure of fatty acid is constant - but hydrocarbon tail varies.
Tails are hydrophobic - they repel water molecules, meaning lipids are insoluble in water.
How are triglycerides formed?
Through three condensation reactions - each one results in a fatty acid bonding to the glycerol molecule.
What joins the fatty acid to the glycerol molecule in triglycerides?
What is released when this happens?
An ester bond.
Water molecule is released when ester bond forms.
Draw the basic structure of a fatty acid:
- carbon atom links fatty acid to glycerol
- variable ‘R’ group indicates the hydrocarbon tail.
Draw the condensation reaction that leads to the formation of a triglyceride:
What does the hydrolysis of a triglyceride produce?
A glycerol molecule and three fatty acids.
What are the two types of fatty acids?
Where does the difference between these two types occur?
Saturated and unsaturated.
The differences between these two types occurs in their hydrocarbon tails.
What is the difference between saturated and unsaturated fatty acids?
Saturated = don’t have any double bonds between their carbon atoms.
Unsaturated = have at least one double bond between carbon atoms - this causes the chain to kink.
What is the main use of triglycerides?
Energy storage molecules.
What is it called when there is only one double bond present in a fatty acid?
What is it called when there is more than one double bond present in a fatty acid?
Mono-unsaturated.
Polyunsaturated.
How does the structure of triglycerides relate to their function?
- High ratio of energy-storing carbon-hydrogen bonds present in fatty acid tails - this chemical energy is released when broken down.
- Insoluble as they are large and non-polar - so their storage does not affect the water potential of the cell/cause water to enter by osmosis.
- Low mass to energy ratio - a lot of energy can be stored in a small volume, which is beneficial to animals as they then have less mass to carry.
- High ratio of hydrogen to oxygen atoms - so water is released when they are oxidised, meaning they are a good water source for animals living in a dry, desert habitat.