Lipids Flashcards
What are the 2 groups of lipids
Triglycerides and phospholipids
How are triglycerides formed
By the condensation of one molecule of glycerol and 3 fatty acid molecules which removes 3 water molecules to form ester bonds
Why are triglycerides not polymers
Because they arnt made of the same monomers
What do fatty acid chains consist of
Hydrocarbon chain and a carboxylique acid group
They vary in length and can be referred to as “R”
What can the entire fatty acid be referred to as
RCOOH
What happens during the formation of triglycerides
3 fatty acids join to the glycerol molecule via condensation reaction
Each time an ester bond is produced
A water molecule is a by product of each reaction. This means for every triglyceride molecule produced 3 water molecule are produced
What is a saturated fatty acid
Don’t have any double bonds between carbon atoms in the hydrocarbons chaisn
What is an unsaturated fatty acid
Have double bonds between carbon atoms in the hydrocarbon chain
What are the properties of triglycerides
Long hydrocarbon fatty acid chains- contain lots of stored chemical energy which is used as an energy storage molecule
Hydrophobic fatty acid tails- insoluble in water and doesn’t affect water potential of a cell and won’t dissolve when in contact with water
What does hydrophobic mean
Repeals water which makes lipids insoluble in water
What are the fatty acid tails
Hydrophobic so They face inwards shielding themselves from water with their glycerol heads
What is the difference between phospholipids and tryglicerides
One of the fatty acids is replaced by a phosphate group so the glycerol combined with 2 fatty acids and 1 phosphate groip
What does a phosphate group have
Phosphate group has negative charge (polar) whereas the fatty acid tails don’t have a charge (non polar)
This allows the phospholipids to form a bolster in water
How are phospholipids arranged
The hydrophobic fatty acid tails are arranged in the middle away from water and the hydrophilic phosphate heads are arranged onthe outside in contact with water
Describe and explain how the phospholipids are arranged in a cell membrane
In a cell surface membrane phospholipids form a bilayer. The phosphate heads face outside the cell in contact with water because they are hydrophilic. The fatty acid tails face inwards away from the water because they are hydrophobic
What is the functions of phospholipids
Hydrophoci fatty acid tails and hydrophilic phosphate heads. This will form a phospholipid bilayer with hydrophobic fatty acid tails pointing in away from the water and hydrophilic phosphate heads pointing towards the water. This is useful because it forms cell membranes and the hydrophobic fatty acid centre means that water soluble molecules can’t easily pass across the membranes
What is the name of the test for lipids
The emulsion test
What is the method for the emulsion test
Add 2 cm ethanol and shake (dissolves the lipids)
Then add water drop wise and shake
If lipids are present a white emulsion will be visible
How can you evaluate conclusions in graphs
Advantages- shows a correlation and relationship
Disadvantages- can be due to another factor
Only one investigation so many not be representative
Could be a time issue or due to weather
Only on one farm
