Lipids - Triglycerides

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  • Created by: shyde7
  • Created on: 28-03-16 11:19
Lipds contain larger amounts of which elements?
Carbon and Hydrogen
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Lipds contain smaller amounts of which element?
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Why are lipids insoluble in water?
Because they are not polar and so do not attract water molecules.
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What do lipids dissolve in?
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What are the three most important lipids in living things?
Triglycerides, phospholipids and steroids.
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What is important about the structure of triglycerides, phospholipids and steroids?
They're not polymers, but do have different components bonded together. They're examples of macromolecules.
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Triglycerides are made of which two molecules?
One glycerol and three fatty acids.
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What are essential fatty acids?
Fatty acids that we cannot make in our bodies - they must be injested complete.
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How many carbon atoms does glycerol have?
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Why is the fact that glycerol is an alcohol important?
It means it has three free -OH groups, which is important to the structure of triglycerides.
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What is a carboxyl group?
A molecule made of one carbon atom, two oxygen atoms and one hydrogen atom. Written -COOH
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In fatty acids, where is the carboxyl group attached?
At one end, attached to a hydrocarbon tail.
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How many carbons are in the hydrocarbon tail of the fatty acid?
Between 2 and 20.
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What makes a fatty acid an acid?
The carboxyl group ionises into H+ ions and a -COO- group. The production of free H+ ions is what makes it an acid.
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What makes a fatty acid saturated?
When there are no C=C bonds in the molecule.
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What makes a fatty acid unsaturated?
When there is a double bond between carbons meaning fewer hydrogen atoms can be bonded.
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What is a monounsaturated fatty acid?
When there is a single C=C bond (e.g. oleic acid)
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What is a polyunsaturated fatt acid?
When there is more than one C=C bond (e.g. linoleic acid)
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How does being unsaturated affect the shape of a fatty acid?
The double bond gives the molecule a kink, which pushes the molecules apart slightly. This makes them more fluid.
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Which type of fatty acids do animal lipids cotain a lot of?
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What effect does the double bond have on meltig points?
Saturated fatty acids are solid at 20 degrees celcius whereas the melting point is lower in unsaturated fatty acids.
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The -COOH group of the fatty acid and the -OH group of the glycerol bond by which reaction?
A condensation reaction.
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What is produced from the condensation reaction and what effect does this have?
A water molecule is produced and the resulting covalent bond is known as an ester bond.
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Are the fatty acids in a triglyceride the same or different?
They do not have to be the same, they can be different.
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What happens to triglycerides during respiration?
They can be broken down in respiration to release energy and generate ATP.
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The first step in respiration of a lipid is hydrolysing the ester bonds: what does this allow to happen?
The glycerol an fatty acids can be broken down completely to carbon dioxide and water.
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Is more of less water produced from respiration of a lipid than respiration of a sugar?
More water is produced.
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What makes a triglyceride a good energy store?
Because they are insoluble, they can be stored within the cell without affecting the water potential.
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In which cells do mammals store fat?
Adipose cells under the skin.
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Why does one gram of fat release twice as much energy as one gram of glucose?
Because lipids have a higher proportion of hydrogen atoms than carbohydrates and almost no oxygen atoms.
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What function does adipose tissue serve in whales?
It is a storage location of lipids (blubber) but more importantly acts as a heat insulator.
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What function do lipids serve in nerve cells?
Lipids act as electrical insulators.
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Why is fat iportant to aquatic mammals?
It is less dense than water and so helpsthem float. (Buouancy)
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Why do humans have fat around delicate organs?
Acts as a shock absorber.
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For which other organism does fat provide protection?
Bacteria. The peptidoglycan cell wall of some in covered in a lipid-rich outer coat.
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What type of lipid makes insects and leaves waterproof.
Wax. Waxes are made by combining fatty acids with alcohol molecules much larger than glycerol.
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Lipds contain smaller amounts of which element?



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Why are lipids insoluble in water?


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What do lipids dissolve in?


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What are the three most important lipids in living things?


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