Name: ___________________________ Class: _________________ Date: __________ Chapter 10 : Membrane Structure 1. What is the typical thickness of a lipid bilayer such as the plasma membrane of our cells? a. 0.5 nm b. 5 nm c. 50 nm d. 100 nm e. 500 nm 2. In the following schematic drawing of an abundant plasma membrane phosphoglyceride, which part is positively charged? a. Part A b. Part B c. Part C d. Part D e. Part E 3. Which of the following is NOT correct regarding the molecule whose structural formula is shown below? a. It is an amphiphilic molecule. b. It is a sterol. c. It makes the membrane less permeable to small hydrophilic molecules. d. It is found in membranes of virtually all living cells. e. It affects the fluidity of the lipid bilayer. 4. Which of the following is NOT natura lly found in a eukaryotic membrane? a. Cholesterol b. Phosphatidylinositol c. Sphingomyelin d. Ganglioside G M1 e. Octylglucoside 5. The compound isobutane, formula HC(CH ₃)₃, is added to water. How will it interact with the water molecules? a. The partial negative charge on water will interact with the partial positive on isobutane. b. The partial positive charge on water will interact with the partial negative on isobutane. c. The nonpolar patches on water will interact with the nonpolar patches on isobutane. d. There will be no interaction, because water will form a cage around isobutane. 6. The motion of lipid molecules in a synthetic bilayer can be studied by various techniques. Which of the following has been observed in these systems? a. Phospholipids diffuse rapidly within and b etween the two leaflets of a bilayer. b. An average lipid molecule can diffuse the length of about 2 micrometers in a fraction of a millisecond. c. The flip -flops are very rare for phospholipids but cholesterol molecules flip -
flop more often. d. Within a bilayer, l ipid molecules rarely rotate about their long axis, but diffuse laterally at very high rates. 7. Why do liposomes not fuse with one another spontaneously when suspended in an aqueous environment? a. Because fusion requires a large number of flip -flops, which a re very rare. b. Because the hydration shell of the polar head groups of the lipids needs to be removed. c. Because fusion requires micelle formation. d. Because of the rapid lateral diffusion and rotation of the lipid molecules.
flop more often. d. Within a bilayer, l ipid molecules rarely rotate about their long axis, but diffuse laterally at very high rates. 7. Why do liposomes not fuse with one another spontaneously when suspended in an aqueous environment? a. Because fusion requires a large number of flip -flops, which a re very rare. b. Because the hydration shell of the polar head groups of the lipids needs to be removed. c. Because fusion requires micelle formation. d. Because of the rapid lateral diffusion and rotation of the lipid molecules.
