1.3 Lipids Flashcards
What are lipids used for?
Insulation Energy store Protection of organs Make up cell membranes Waxy cuticle layer (waterproofing)
What is a common lipid called?
Triglyceride
Is a triglyceride a polymer? Why?
No
I has no repeated sub-units
What elements is a triglyceride made from?
Carbon
Hydrogen
Oxygen
Far more carbon and hydrogen than oxygen
How is a triglyceride built?
4 molecules
1 glycerol molecule
3 fatty acid chains attached
What is the main property of triglycerides?
It is insoluble in water as no OH groups
Therefore hydrophobic
(The glycerol and fatty acid chains are separately soluble)
What are lipids soluble in?
Organic solvents
Alcohols and acetone
What is the general formula of a fatty acid?
RCOOH
O || R-C-O-H
What are the two types of fatty acids?
Saturated
Unsaturated
What are the properties of saturated fatty acids?
All single carbon carbon bonds
Straight chains
Denser
Solid at room temperature - eg animal fat
What are the properties of unsaturated fatty acids?
One or more carbon carbon double bonds
Bent chains
Less dense
Liquids at room temperature - eg plant oils
What are the different names for unsaturated chains?
Monosaturated (1 c=c)
Polyunsaturated (+1 c=c)
What is the structure of glycerol?
H H H
| | |
H- C - C - C - H
| | |
OH OH OHWhat reaction forms a triglyceride?
Condensation reaction
What bond is formed in condensation of glycerol and fatty acid chains? How many?
Ester bond
3 bonds
What are the products are formed in a condensation reaction?
1 triglyceride molecule
3 waters
What are the uses of triglycerides?
Energy rich - high ratio of C-H bonds
Good storage - large non-polar molecules, don’t affect osmosis and low mass to energy ratio
Source of water - release water when oxidised as high ratio of H-O (good for camels)
What is the test for lipids?
Add 5cm3 of alcohol(ethanol) to 2cm3 of the sample
Crush up first if solid sample (seeds)
Possible filtration if solid present
Shake the solution to dissolve the lipid
Add 5cm3 of water and shake
A cloudy white emulsion indicates presence of a lipid
Repeat with water as the sample to compare as a control group
Why is a cloudy white emulsion formed in the lipids test?
You are putting two immiscible liquids together forming an emulsion
What is another type of lipid?
Phospholipid
How is the structure of a phospholipids different?
It has only 2 fatty acid chains attached to the glycerol and 1 phosphate group attached instead
What are the properties of the glycerol/phosphate group head?
Hydrophilic
As the phosphate is charged so can be dissolved in water (PO4 ^-)
What are the properties of the 2 fatty acid tails?
Hydrophobic
They are non-polar regions
What are uses for phospholipids?
Cell membranes - phospholipid bilayer
What is formed when water is added to a phospholipid?
Micelle
Looks like a ring with the hydrophilic head on the outside and very inside
Leaving the hydrophobic tails on the inner forming an area of fatty acid tails with no water
