Lipids are not polymers.

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  • Created by: racheon
  • Created on: 12-04-14 14:42
Define lipids.
A diverse group of chemicals that dissolve in organic solvents but not water.
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How much of the organic matter of a cell do lipids make up?
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At room temperature, what do we call lipids that are in a solid and a liquid state.
Solid lipids are fats, liquid lipids are oils.
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What roles do lipids play within organisms?
They're a source of energy, used for energy storage, used in biological membranes, used in insulation, used in protection and make some hormones.
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What elements do lipids contain?
Carbon, hydrogen and oxygen.
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How high is the proportion of oxygen in lipids?
Low, lower than that found n carbohydrates.
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Where are glycerol and fatty acids found in organisms?
All the fats and oils that perform roles in energy storage and supply, and those found in membranes.
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What makes glycerol and fatty acids different?
Glycerol molecules are the same, fatty acid molecules can differ.
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What are fatty acids that animals can't make called, and how do they obtain them.
They're called essential fatty acids, and they must be taken in 'complete' as part of the diet.
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What is similar in all fatty acids?
They all have an acid or carboxyl group at 1 end which is the same as that found on an amino acid.
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Apart from an acid group, what is a fatty acid made of?
A hydrocarbon chain 2 to 20 carbons long, most commonly around 18.
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What kind of lipids are health and what kind are unhealthy?
Unsaturated of polyunsaturated are healthy, saturated are unhealthy.
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What do the terms unsaturated, polyunsaturated and saturated refer to?
Whether the hydrocarbon chain is 'saturated' with hydrogen.
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What do unsaturated lipids have that saturated lipids don't have, and what does this mean?
C=C bonds, so fewer hydrogen atoms can bond to the chain.
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What is an unsaturated lipid with 1 C=C bond called?
A mono-unsaturated fatty acid.
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What is an unsaturated lipid with 2 or more C=C bonds called?
A polyunsaturated fatty acid.
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What does introducing a C=C bond do to a fatty acid?
It changes the shape of the hydrocarbon chain, making the molecules in a lipid push apart, so makes them more fluid, meaning lipids containing many unsaturated fatty acids are often oils, but those with mainly saturated are often fats.
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What is the difference between animal and plant lipids?
Animal lipids contain many saturated fatty acids, whereas many plant lipids contain many unsaturated fatty acids.
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What do triglycerides consist of?
1 glycerol molecule bonded to 3 fatty acid molecules.
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How are glycerol and fatty acid molecules bonded?
In the same way, by a condensation reaction between the acid group of a fatty acid and 1 OH group of the glycerol to form a covalent bond called an ester bond.
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What is produced after 1 condensation reaction between glycerol and a fatty acid?
A monoglyceride molecule and a water molecule.
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How do you form a triglyceride molecule from a monoglyercide molecule?
Condensation reactions between acid groups of 2 more fatty acid molecules and the 2 remaining OH groups on the glycerol.
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Why do triglyceride molecules not dissolve in water, and what does this make them?
Because the charges on the molecule are distributed evenly, meaning hydrogen bonds can't form with water molecules, so they're hydrophobic.
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Are lipids more or less dense than water?
Less dense than water.
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How many carbons does a glycerol molecule contain, and what is each bonded to?
3, each bonded to a hydroxyl group.
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Draw the reaction between 1 glycerol and 3 saturated fatty acids to form a triglyceride. Label.
Glycerol - CH₂OH-CHOH-CH₂OH. Saturated fatty acid - HO-C(=O)-(CH₂)n-CH₃. The OH group on each fatty acid and the H of each hydroxyl group react, leaving 3 water molecules and CH₂-O-C(=O)-(CH₂)n-CH₃ x3 (middle one CH)
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What do plants and animals use triglycerides for?
Energy stores, thermal insulators, buoyancy, protecting internal organs, and a source of water when respired.
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