Biology: Biochemistry Lipids Quiz – Flashcards
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What three elements do lipids contain?
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carbon, hydrogen and (small amounts of) oxygen
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what is the difference between a fat and an oil?
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a fat is solid at room temperature and an oil is liquid at room temperature
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what is a triglyceride
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a molecule made up of a glycerol and three fatty acids joined by three ester bonds
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what is a fatty acid made of?
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a carboxyl (COOH) group with a hydrocarbon 'tail'
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what is an unsaturated fatty acid?
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a fatty acid with a double carbon bond
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what is an saturated fatty acid?
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a fatty acid without a double carbon bond
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a triglyceride with one unsaturated fatty acid is...
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monounsaturated
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a triglyceride with two or more unsaturated fatty acids is...
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polyunsaturated
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what are the uses of triglycerides?
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energy stores, buoyancy, thermal insulation, electrical insulation, water proofing
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what are they found in in animals
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adipose tissue
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are triglycerides polar or nonpolar?
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nonpolar
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with the nonpolarity in mind, are triglycerides hydrophillic or hydrophobic?
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hydrophobic
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what are saturated fats usually found in?
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animals
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what are unsaturated fats usually found in?
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plants
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if a membrane has lots of saturated fats it is more likely to...
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be less fluid and stable at higher temperatures
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if a membrane has lots of unsaturated fats it is more likely to...
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be more fluid and less stable at higher temperatures
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therefore an animal who lives in the cold wants a membrane with more...
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unsaturated fats
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and an animal who lives in the heat wants a membrane with more...
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saturated fats
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what is a phospholipid?
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a lipid with two fatty acids joined to a glycerol group by two ester bonds but with the addition of a phosphate group instead of a third fatty acid
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what are phospholipids used for?
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constructing phospholipid bilayers as membranes
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why does a phospholipid form this bilayer?
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the head of the phospholipid is polar and therefore hydrophillic and the tails are nonpolar and therefore hydrophobic
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what is a cis fatty acid?
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a fatty acid with hydrogens on the same side of the double bond
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what is a trans fatty acid?
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a fatty acid with hydrogens on the opposite side of the double bond
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do trans fatty acids exist in nature? are they good for you?
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they do not exist in nature. they are very bad for us.
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what is the emulsion test?
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a test to test for the presence of lipids
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describe the emulsion test
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crush substance sufficiently if it is a solid place substance in a test tube with ethanol shake vigourously place substance in water droplets will form, indicating an emulsion the mixture will turn milky/white
