A - 4 - Lipids Flashcards
Describe the structure of a triglyceride
Triglycerides have one molecule of glycerol and three fatty acids attached to it
What are fatty acids ‘tails’ made up of?
Hydrocarbons
What is the difference between a saturated and a non saturated fatty acids
Saturated fatty acids don’t have double bonds between their carbon atoms (the fatty acid is saturated with hydrogen) whereas non-saturated fatty acids do have double bonds between their carbon atoms
What is the bond formed between a fatty acid and a glycerol molecule?
An ester bond
Which reaction forms an ester bond?
A condensation reaction
Describe the structure of a phospholipid
- There are two fatty acid molecules
- One molecule of glycerol
- A phosphate group
Which lipids are found in cell membranes?
Phospholipids
What are triglycerides mainly used for?
They are used as energy storage molecules
How does the structure of a triglyceride relate to its function?
- Their long hydrocarbon tails contain lots of chemical energy which is released when they are broken down
- They are insoluble in water so they do not affect the water potential. This is because the hydrophobic tails face inwards and so they shield themselves from water with their hydrophobic heads
What is the function of a phospholipid?
They make up the bilayer of cell membranes
How does the structure of a phospholipid relate to its function?
-Their heads are hydrophilic and their tails are hydrophobic so they form a double layer with their heads facing outwards towards the water on either side. The centre of the bilayer is hydrophobic so water soluble substances cannot easily pass through it therefore it acts as a barrier
Which test is used to see if. there is a lipid present in a substance
The emulsion test
Describe the emulsion test
- Shake the test substance with ethanol for about a minute
- Pour the solution in water
- Any lipid will show up as a milky emulsion
