Lipids Flashcards
Triglycerides/ Phospholipids/ Saturated / Bilayer
What is different about lipids compared to carbohydrates, proteins and nucleic acids? (1)
Lipids are NOT polymers whereas the others are
What are some functions of lipids? (6)
- Source of energy (respiratory substrates)
- Insulate organisms
- Protect delicate organs like kidneys
- Act as waterproofing in plants
- Form membranes (phospholipid bilayer)
- Form hormones
What are the 2 types of lipids called? (2)
- Triglycerides
- Phospholipids
What is a triglyceride made up of? (2)
- 1 glycerol molecule
- 3 fatty acid chains
What bond is formed in a triglyceride and between what (2)
- An ester bond is formed
- between the 3OH (hydroxyl) groups on the glycerol molecule and the OH group on each fatty acid chain
Are triglycerides polar or non-polar? (1) so? (1)
- Triglycerides are non-polar
- so they are insoluble in water
Are fatty acids hydrophobic or hydrophilic (1) and define both terms (2)
- Fatty acids are hydrophobic
- Hydrophobic - Repels water
- Hydrophilic - Attracts water
Why do lipids form droplets in water? (1)
They are insoluble due to the hydrophobic fatty acid chains
Are the hydrocarbon fatty acid chains in triglycerides saturated or unsaturated? (1) and define both terms (2) including both types of unsaturated fatty acids (2)
- The hydrocarbon fatty acid chains can be either saturated or unsaturated
- Saturated - When the carbon chain doesn’t contain a carbon to carbon double bond
- Unsaturated - When the carbon chain contains a carbon to carbon double bond
- Mono-unsaturated - theres only one carbon to carbon double bond
- Poly-unsaturated - theres multiple carbon to carbon double bonds
State 4 ways in which the structure of triglycerides is useful (4)
- Triglycerides are a good energy store as they release energy when the ester bond between the fatty acid chains and broken
- Triglycerides are large and non-polar so they are insoluble in water and their energy storage doesn’t affect water potential.
- There is a high ration of hydrogen to oxygen so it can produce water when oxidised which is useful for organisms living in hot environments
- They can carry more energy in a smaller amount of volume which is useful for animals as they can carry less mass around
What is a phospholipid made up of? (3)
- 1 glycerol molecule
- 2 fatty acid chains
- 1 phosphate group
What bonds are there in a phospholipid and where? (2)
- An ester bond
- between the 2 OH groups on the glycerol molecule and the OH group on each fatty acid chain
What is the structure of a fatty acid? (2)
- Carboxyl group (COOH )
- with a hydrocarbon chain attached
Are phospholipids polar or non-polar? (2)
- The phosphate heads are polar
- The fatty acids tails are non-polar
Are phospholipids hydrophobic or hydrophilic? (2)
- The phosphate heads are hydrophilic (attract water)
- The fatty acid tails are hydrophobic (repels water)
Give two examples of where phospholipids can be found (2)
- Membranes
- Hormones e.g. testosterone
How are phospholipid bilayers formed? (2) What does this do? (3)
- The hydrophobic tails face inwards so the hydrophilic heads face outwards
- creating a hydrophobic centre
- which acts as a barrier against water soluble substances
- it can create different conditions on either side of the membrane
- as it allows separation of solutions
What can double bonds (unsaturated fatty acid) do to the shape of a chain? (1)
Cause it to bend or kink
