Chapter 3- Lipids Flashcards
What are triglycerides?
They are macromolecules and a type of lipid. They have one molecule of glycerol and 3 fatty acids attached to it.
What chemical elements make up lipids
Carbon, Hydrogen and oxygen
What part of the triglyceride is hydrophobic?
The fatty acid tails. These tails make lipids insoluble in water.
How are triglycerides synthesised?
The formation of an ester bond between each fatty acid and the glycerol. This reaction produces one triglyceride and 3 molecules of water.
What type of reaction is the synthesis of triglycerides?
Each ester bond is formed by a condensation reaction. However the overall synthesis is called esterification
What type of reaction breaks down triglycerides?
Each ester bond is broken down by a hydrolysis reaction.
What are the two types of fatty acids?
Saturated and unsaturated
What is the Difference between saturated and unsaturated fatty acids?
Saturated fatty acids don’t have any double bonds between their carbon atoms, they are saturated with hydrogen.
Unsaturated fatty acids have at least 1 double bond between carbon atoms, which cause the chain to kink.
What is a phospholipid?
They are also macromolecules. They are similar to triglycerides except one of the fatty acid molecules is replaced with a phosphate group. The phosphate group is hydrophilic and the fatty acid tails are hydrophobic.
What is the main function of triglycerides?
In animals and plants, triglycerides are mainly used as energy storage molecules. Some bacteria use triglycerides to store both energy and carbon
How does the structure of triglycerides relate to its function?
1) the long hydrocarbon tails of the fatty acids contain lots of chemical energy, a load of energy is released when they’re broken down. This means they contain about twice as much energy per gram as carbohydrates
2) they’re insoluble so they don’t cause water to enter cells by osmosis, which would make them swell. Triglycerides bundle together as insoluble droplets in cells because of the fatty acid tails being hydrophobic ans the tails shielding themselves inwards. This forms a ring like structure.
What is the main function of phospholipids?
They are found in the cell membrane of all eukaryotes and prokaryotes. They make up the phospholipid bilayer and can control what enters and leaves the cell.
How does the structure of phospholipids support its function?
1) they have a hydrophilic head and their tails are hydrophobic so they form a double layer with their heads facing towards the water in either side.
2) the centre of the bilayer is hydrophobic, so water soluble substances can’t easily pass through it. The membrane acts as a barrier to those substances.
What is the structure of cholesterol?
It has a hydrocarbon ring structure attached to a hydrocarbon tail. The ring structure has a polar hydroxyl (OH) group attached to it.
What is the main function of cholesterol?
In eukaryotic cells, it helps to regulate the fluidity of the cell membrane by interacting with the phospholipid bilayer.
