3.1.3 LIPIDS Flashcards
What do lipids contain?
Carbon
Hydrogen
Oxygen
Are lipids soluble or insoluble in water?
Insoluble
Non- polar and hydrophobic
Two groups of lipids:
- Triglyceride (main component of fats + oils)
- Phospholipids
Monomers of triglycerides;
Glycerol and three fatty acids
What are lipids?
NOT polymers
What are fats soluble in?
Organic solvents such as alcohols- why the lipid emulsion test works
How are triglycerides formed?
- condensation reaction
- ester bond (a covalent bond) forming between glycerol + fatty acids
- hydrolysis forms glycerol + fatty acids
- 3 molecules of water produced
Roles of triglycerides:
- protection of organs
- cell membranes
- insulation
- buoyancy
- energy store
Structure VS function of a triglyceride:
Structure: more CH bonds
Function: energy store
Fats are components of cell membranes….
They add flexibility and allow soluble substances to cross them
Fats are a source of energy….
When oxidised they provide twice the energy for the same mass if carbs aswell as releasing more water in the process
Fats can be used for waterproofing…
They are insoluble in water which is why plants and insects have waxy lipid cuticles and animals such as penguins secrete oils
Saturated fatty acids do not contain…
A carbon- carbon double bond
Therefore, the hydrogen is saturated
Saturated fatty acids don’t contain…
A carbon- carbon double bond
Therefore, the hydrogen is saturated
Unsaturated fatty acids do contain…
Carbon=carbon double bonds
They cause the hydrocarbon chain to bend/kink
What do fatty acids contain?
- a methyl group at one end of a hydrocarbon chain known as the “R” group
- at the other end is a carboxyl group
The shorthand chemical formula for a fatty acid is…
RCOOH
How do fatty acids vary?
- length of hydrocarbon chain (R group)
- fatty acid chain (R group) may be saturated or unsaturated
How do unsaturated fatty acids vary?
Can by mono or poly-unsaturated
How many fatty acids are bonded to a glycerol molecule in a phospholipid?
Two fatty acids joined to a glycerol molecule because one has been replaced by a phosphate ion
Is the phosphate ion in a phospholipid soluble in water?
Yes, as it is polar
It is hydrophilic
Are the fatty acids tails in a phospholipid soluble in water?
- No, they are non- polar
- They are Hydrophobic
Phospholipids are ……….. (they have both hydrophobic and hydrophilic parts)
Amphipathic
- as a result of having both parts, phospholipid molecules form monolayers or bilayers in water
Role of phospholipids:
Main component of cell membranes
What is created due to the presence of hydrophobic fatty acid tails when a phospholipid bilayer forms?
- hydrophobic core
- acts as a barrier to water- soluble molecules
