Topic 1.2 Lipids Flashcards
What elements are lipids made up of?
Carbon, hydrogen and oxygen
Name the two types of lipids.
Fats and oils
Are lipids soluble or insoluble?
Soluble in non-polar solvents, insoluble in water
What are some of the functions of lipids?
Source of energy, membrane component, waterproofing, hormones, energy storage, insulation
What are triglycerides made up of?
A glycerol molecule and three fatty acids
What is the reaction in which triglycerides are formed?
A condensation reaction
What are the bonds between the glycerol and fatty acids?
Ester bonds
How is the reaction sped up?
Enzymes
What is the structure of a fatty acid?
Acid group at one end with a hydrocarbon chain attached
What is the difference between a saturated and an unsaturated fatty acid?
Saturated has no double bonds but an unsaturated fatty acid has double bonds
Are saturated fats oils or solids?
Solids
Are unsaturated fats oils or solids?
Oils, because the double bond lowers their melting point
What does monounsaturated mean?
Just one double bond in the chain
What does polyunsaturated mean?
Many double bonds
How does a C=C bond affect the shape of a fatty acid?
Puts a kink in the hydrocarbon chain which causes it to bend
Why are saturated fatty acids more likely to be solid?
Because the straight chains make them closer so there are stronger intermolecular forces between them
Why are unsaturated fatty acids more likely to be liquid?
Because the double bonds creates a bigger distance between the chains so the intermolecular forces are weaker
What are the three roles of lipids?
Energy storage, waterproofing and insulation
When do triglycerides release energy?
When they’re oxidised in respiration
How are lipids better energy stores than carbohydrates?
They release twice as much energy so they’re more concentrated energy stores
In what kind of animals are fat stores found?
In animals that go long periods of time without food and must rely on their energy store
Why do lipids repel water?
Because they’re hydrophobic
How is lipids’ waterproof property used?
Oils are secreted by the sebaceous glands in the skin of mammals so the fur of the animal becomes oily and therefore water-repellent
How are lipids used as insulation?
Stored in mammals as adipose tissue (subcutaneous fat). Blood doesnt circulate to this tissue so heat isnt transferred there so the heat of the body stays near the core which means there is a smaller heat gradient so heat isnt lost as quickly
Compare the structure of phospholipids to triglycerides
Same structure except one of the fatty acid groups is attached to phosphate group
Is a phospholipid group hydrophillic or hydrophobic?
The head is hydrophillic bc of the phosphate group forming hydrogen bonds with the water. The fatty acid chains are hydrophobic
How do phospholipids form a monolayer?
When phospholipids come in contact with water the heads dissolve in water and the tails stick out
