GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with Lipids
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
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Example Questions
Example Question #11 : Macromolecules And Enzymes
Which type of lipid acts as a buffer for membrane fluidity?
Terpenes
Sterols
Phospholipids
Glycolipids
Sterols
Membrane fluidity can be buffered by cholesterol in both warm and cold environments. At high temperatures cholesterol raises the melting point, while at lower temperatures cholesterol prevents the formation of crystalline structures between phospholipids.
Example Question #1 : Help With Lipids
Phospholipids are comprised of __________.
a glycerol head and two sphingolipids
a glycerol head containing a phosphate group and two fatty acids
a glycerol head containing a phosphate group and three fatty acids
a chain of saturated fats
a sugar, phosphate group, and nitrogenous base
a glycerol head containing a phosphate group and two fatty acids
The correct answer is a glycerol head containing a phosphate group and two fatty acids. Phospho refers to the phosphate group and lipid refers to the glycerol backbone attached to two fatty acid chains.
Example Question #2 : Help With Lipids
What qualifies a molecule to be considered an omega-3 fatty acid?
The attachment of three of the same fatty acid to a glycerol
The presence of a double bond on the third-to-last carbon in the fatty acid
The presence of three double bonds in the fatty acid
The presence of a double bond on the third carbon in the fatty acid
The presence of a double bond on the third-to-last carbon in the fatty acid
Omega-3 fatty acids are named after the double bond that starts on the third-to-last carbon in the fatty acid. The carboxylic acid carbon is considered the first carbon, while the last methyl group carbon is considered the "omega" carbon. As a result, the double bond will be three carbons away from the end.
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