Bee Brittain
Flashcards by , created over 3 years ago

AS - Level Biology (1 - Biological Molecules) Flashcards on Lipids, created by Bee Brittain on 03/11/2016.

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Bee Brittain
Created by Bee Brittain over 3 years ago
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Question Answer
What elements make up Lipids? Carbon, Hydrogen and Oxygen
Lipids have a characteristic that means they wont effect water potential, what is this characteristic? They are Insoluble
Lipids are soluble in two substances though! Name them. Alcohol and Acetone
Lipids are a useful source of energy, why? when oxidised, lipids provide over 2x the energy of carbohydrates
Lipids make a good waxy cuticle on plants and insects, why? Lipids are insoluble, so this means they are waterproof and provide a good waterproof coating for most organisms
Why are lipids good insulators? Lipids are slow conductors of heat, meaning when stored, they help retain body heat. They also act as electrical insulators in the myelin sheath around nerve cells
Lipids can be found around vital organs, why? Fat is often stored around delicate organs as it provides a form of protection
Name two types of lipid Triglyceride and Phospholipid
What does it mean if a fatty acid is: 1) Monounsaturated? 2) Polyunsaturated? 3) Saturated? 1) Monounsaturated = 1 Double Bond 2) Polyunsaturated = Many Double Bonds 3) Saturated = No Double Bonds
What makes triglycerides an excellent source of energy? They have a high ration of C-H bonds compared to C atoms
What feature of triglycerides makes a good storage molecule? They have a low mass to energy ratio, so you don't need much to have enough energy so they store well. This is beneficial to many animals
Are triglycerides polar or non-polar? They are non-polar (this is also why they are insoluble!)
When oxidised, what do triglycerides release? They release water, this makes them useful to animals as they provide a source of water for organisms who live in hotter/dryer enviroments
Are phospholipids polar or non-polar? Polar
What feature of a cell do phospholipids make up? How come they are suited to this feature? They make up the phospholipid bi-layer. They are suited to this because phospholipids have a hydrophobic 'tail' (the fatty acids) and a hydrophilic 'head' (the phosphorus group) so they form a double layer with the 'heads' facing out and the 'tails' facing in.
Name two differences between the structure of a triglyceride and a phospholipid? A triglyceride has 3 fatty acids, and a glycerol molecule. On the other hand, a phospholipid has only 2 fatty acids, a glycerol and a phosphate group.
Describe the steps in the test for a lipid. - Add ethanol to the test tube containing the sample - Shake tube throughly, dissolving the sample in the ethanol - Add Water and shake gently
If there is a lipid present, what will happen to the solution in the test? It will turn cloudy white as an emulsion has been formed.