ANSWERS TO CHAPTER FOUR 1. Answer: b. Each of these is a part of the triglyceride molecule, except for a carboxylic acid portion. It is basically three fatty acids connected to glycerol via an ester bond. 2. Answer: d. The phospholipid is very similar to the triglyceride molecule; however, instead of three fatty acids, it has two fatty acids and a phosphate group in place of the third fatty acid moiety seen in the triglyceride molecule. 3. Answer: c. Each of these is associated with fatty acid synthesis except for muscle tissue. In each of the listed areas, fatty acids can be made after acetyl CoA is made through the glycolytic process from glucose in the cytoplasm. 4. Answer: b. Palmitic acid is a 16-carbon fatty acid that is the endpoint of fatty acid synthesis with fatty acid synthase. It takes other reactions to lengthen this fatty acid or to desaturate it. 5. Answer: a. Glycolipids are only found on the outside of the cell membrane. They have their carbohydrate portion sticking out from the cell. 6. Answer: c. Peripheral proteins lie on the outer surface of the cell. They are hydrophilic in general and can be isolated without necessarily disrupting the cell membrane. 7. Answer: d. The outer part of a cell is called the glycocalyx, because it has carbohydrates attached to the protein molecules, which can be transmembrane proteins or surface proteins. 8. Answer: a. Transporter proteins transport ions and small molecules across the cell membrane because otherwise the cell membrane would be more impermeable to these types of molecules. 9. Answer: c. Membrane receptor proteins allow for chemical signaling both inside and outside of the cell. 10. Answer: b. Integral monotopic proteins do not pass all the way through the membrane; however, transmembrane proteins can pass through the cell membrane bilayer several times.
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