AQA Biology Lipids Flashcards
What are the two main types of lipids?
Triglycerides and phospholipids.
What is the structure of a triglyceride?
One glycerol molecule bonded to three fatty acid chains by ester bonds.
How are triglycerides formed?
Through a condensation reaction between glycerol and three fatty acids, forming ester bonds.
What is the difference between saturated and unsaturated fatty acids?
Saturated: No double bonds between carbon atoms. Unsaturated: One or more double bonds between carbon atoms, causing kinks in the chain.
How does the structure of triglycerides relate to their function?
High energy content due to many C-H bonds. Insoluble, so they do not affect water potential. Provide insulation and protection.
What is the structure of a phospholipid?
One glycerol, two fatty acids, and a phosphate group. Hydrophilic head and hydrophobic tails.
How does the structure of phospholipids relate to their function?
Form bilayers in cell membranes, with hydrophobic tails facing inwards and hydrophilic heads facing water. Allow selective permeability of membranes.
What is the test for lipids?
Emulsion Test: Add ethanol to the sample and shake. Add water. A milky-white emulsion indicates the presence of lipids.
Why are triglycerides good for energy storage?
High energy-to-mass ratio. Insoluble in water, preventing water uptake by osmosis.
How are ester bonds formed in lipids?
Through condensation reactions between the hydroxyl group of glycerol and the carboxyl group of fatty acids.
What happens when lipids are hydrolyzed?
They break down into glycerol and fatty acids through the addition of water.
