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5 Student: ___________________________________________________________________________

1. Two “magic” solutions are sold by a research supply company. “Magic Solution A” promises to extract all proteins, including integral membrane proteins, from the plasma membrane. “Magic Solution B” promises to simply extract all peripherally associated membrane proteins. What is the likely composition of “Magic Solution A” and “Magic Solution B”?

A. "Solution A" and "Solution B" both contain high salt buffers that disrupt hydrogen bonds and ionic interactions B. "Solution A" and "Solution B" both include membrane solubilizing detergent(s) C. "Solution A" is a membrane solubilizing detergent, "Solution B" is a high salt buffer that disrupts hydrogen bonds and ionic interactions D. "Solution A" is a high salt buffer that disrupts hydrogen bonds and ionic interactions, "Solution B" is a membrane solubilizing detergent 2. Cellular membranes are

A. flui d. B. solely composed of lipids. C. composed of a single layer of amphipathic molecules. D. selective to the transport of gases and small molecules only. E. found in eukaryotes, but not prokaryotes. 3. What is the major lipid found in membranes?

A. steroid s B. cholester ol C. triglycerid es D. phospholipi ds E. saturated fatty acids

4. The plasma membrane

A. is composed of an extracellular and intracellular layer of phospholipids. B. has extracellular and intracellular layers or leaflets that are highly symmetrical. C. uses cholesterol as its primary lipid. D. contains cellulose. 5. What would be an expected feature of a plasma membrane that had no integral membrane proteins?

A. The membrane would be unable to transport sodium ions B. The membrane would collapse C. The membrane would have no fluidity D. The membrane would have no cholesterol E. The membrane would not associate with peripheral membrane proteins 6. Scientists unearth a Wooly Mammoth from the Siberian Ice Sheath and discover that a eukaryotic "amoeba"-like cell is still alive. Which component of the cell membrane might contribute to maintaining the fluidity of plasma membranes under freezing conditions?

A. peripheral proteins B. high levels of long fatty acyl tails within the lipid bilayer C. high levels of unsaturated fatty acyl tails within the lipid bilayer D. absence of cholesterol E. high levels of saturated fatty acyl tails within the lipid bilayer

7. An artificial membrane vesicle is mixed with several peripheral membrane proteins and analyzed by freeze-fracture electron microscopy. What will be seen in the resulting image?

A. bumps will be visible on both layers B. bumps will be visible only in the extracellular face (E face) C. bumps will be visible in the protoplasmic face (P face) D. No bumps will be visible in either face 8. A scientist produces an artificial membrane from phospholipids and notices that oxygen, but not glucose, readily moves through the membrane. What might account for the inability of glucose to move through the artificial membrane?

A. The artificial membrane lacked a protein needed for glucose transport. B. The artificial membrane lacked the appropriate types of phospholipids for glucose transport. C. Oxygen readily passes through the membrane, so glucose should have as well. D. The membrane lacked an adequate amount of amphipathic molecules for glucose transport. E. Thermodynamics does not allow glucose to pass through membranes produced either artificially or from living organisms. 9. The membrane component(s) primarily responsible for the structure and function of plasma membranes is/are

A. glycosylated proteins. B. phospholipid s. C. glycolipid s. D. nucleic acids. E. cholester ol.

10. If a cell suddenly loses the ability to activate fatty acids by the attachment of a CoA molecule, what will be the most significant impact on the cell membrane?

A. Phospholipids will no longer be synthesized in the ER B. All phospholipid head groups will be identical C. Phospholipids will no longer flip between leaflets D. Cholesterol will no longer be made E. Integral membrane proteins will dissociate from the membrane 11. What feature of the plasma membrane is primarily responsible for the selective uptake and export of ions and molecules from the cell?

A. cellular membranes exhibit fluid-like properties B. the phospholipid lipid bilayer has a hydrophobic interior C. the extracellular leaflet is rich in glycolipids and glycoproteins D. many transmembrane proteins can rotate and move laterally in the plasma membrane 12. When phospholipids are mixed together in an aqueous environment, a membrane bilayer will form spontaneously. In what type of environment would a phospholipid bilayer not form spontaneously?

A. A solution with a high sodium or potassium concentration B. A hydrophobic solvent C. A solution of pure water D. A viscous sucrose solution which slows down the rate of diffusion E. A cold water solution at 10°C

13. What are the two major components of cell membranes?

A. glycolipids and phospholipids B. cholesterol and proteins C. phospholipids and carbohydrates D. phospholipids and cholesterol E. phospholipids and proteins 14. Cell surface molecules are labeled with a fluorescent tag and then a portion of them are bleached with a laser beam. What would one observe after the cell is incubated for a few minutes?

A. The bleached molecules would disappear into the cell. B. The bleached molecules would diffuse laterally through the membrane and intermix with unbleached molecules. C. The bleached molecules would remain in the spot where bleaching occurred. D. All the bleached molecules would flip-flop across the cell membrane. E. The bleached molecules would be released from the cell. 15. In order to study a cell at lower temperatures, a researcher must artificially increase its membrane fluidity. What would be a reasonable strategy for increasing plasma membrane fluidity at low temperatures?

A. decrease the composition of cholesterol in the plasma membrane B. increase the composition of phospholipids with saturated fatty acid chains C. decrease the composition of phospholipids with unsaturated fatty acid chains D. decrease the length of the phospholipid fatty acyl tail. E. All of the above strategies are reasonable

16. What process(es) are required for phospholipids to flip-flop across the lipid bilayer?

A. The process requires energy. B. The process occurs spontaneously, requiring no energy. C. The process requires an enzyme called flippase. D. The process requires energy and the flippase enzyme. E. The process occurs spontaneously and requires the flippase enzyme. 17. Cellular membranes are mosaic and

A. flui d. B. rigi d. C. symmetric al. D. highly permeable to large molecules. E. polar . 18. How might a plant cell compensate for the excessive membrane fluidity that occurs during prolonged exposures to elevated temperature?

A. Reduce membrane cholesterol content. B. Alter the lipid composition to have longer fatty acyl tails and fewer double bonds. C. Alter the lipid composition to have shorter fatty acyl tails and more double bonds. D. Alter the lipid composition to have shorter and more unsaturated fatty acyl tails. E. Reduce cholesterol content and alter the lipid composition to have shorter fatty acyl tails.

19. Glycosylated proteins and lipids within the plasma membrane are important for

A. cell recognition. B. cell protection. C. cell energy storage. D. cell recognition and protection. E. cell protection and energy storage. 20. Which membrane component is most important for allowing large, charged molecules to pass through the membrane?

A. peripheral proteins B. cholester ol C. glycosylated lipids D. transmembrane proteins E. carbohydrate channels 21. Placing celery sticks in fresh water will make them more turgid and harder. This is because

A. the celery is hypotonic to fresh water. B. the celery is hypertonic to fresh water. C. the celery is isotonic to fresh water. D. water moves from the celery sticks into fresh water. E. salt moves from the water into the celery sticks.

22. Which molecule passes through a lipid bilayer most readily?

A. carbon dioxide B. glucos e C. K +

D. arginin e E. RN A 23. Which molecule would you predict moves through a lipid bilayer most rapidly?

A. C6H12O 6

B. CH3O H C. C2H5O H D. C4H1 0

E. NH2SO2CH 3

24. Animal cells are permeable to water and urea but NOT to sucrose. The inside of a cell contains 1 M sucrose and 1 M urea and the outside 1 M sucrose and 2 M urea. The solution inside with respect to outside the cell is

A. hypotoni c. B. turgi d. C. isotoni c. D. saturate d. E. hypertoni c.

25. Animal cells are permeable to water and urea but NOT to sucrose. Initially, the inside of a cell contains 1 M sucrose and 1 M urea and the outside 2 M sucrose and 1 M urea. After the system reaches equilibrium, what changes are observed?

A. The molarity of urea would be higher outside than inside the cell. B. The molarity of sucrose would be similar inside and outside the cell. C. Water would move out of the cell causing the cell to shrivel. D. The molarity of urea would be higher outside the cell and the molarity of sucrose would be similar inside and outside the cell. E. The molarity of sucrose would be similar inside and outside the cell and water would move out of the cell causing the cell to shrivel. 26. Water diffuses through certain organs such as the kidneys and bladder much faster than would occur by passive diffusion through a lipid bilayer alone. What accounts for this more rapid rate of water transport in these organs?

A. The composition of lipids changes to promote water transport. B. Presence of aquaporin channels for facilitated diffusion of water. C. Presence of a water pump. D. Presence of an ATP-driven enzyme for water transport. E. The presence of molecules that bind water and change its membrane permeability properties. 27. Passive diffusion

A. is the process by which molecules move from an area of low concentration to an area of high concentration. B. is a spontaneous process. C. requires the presence of a transmembrane protein. D. will occur so long as the membrane is freely permeable to the solute. E. requires energy.

28. Following a meal, glucose must move from the gut lumen where there is a high glucose concentration into the intestinal cell where there is a relatively low level of glucose. This movement is called

A. passive diffusion. B. facilitated diffusion. C. active transport. D. endocytosi s. E. exocytosi s. 29. The pressure required to stop water from moving across the membrane by osmosis is called

A. transport pressure. B. crenation pressure. C. atmospheric pressure. D. osmotic pressure. E. mechanical pressure. 30. Water diffuses through certain organs such as the kidneys and bladder much faster than would occur by passive diffusion through a lipid bilayer alone. What accounts for this more rapid rate of water transport in these organs?

A. The composition of lipids changes to promote water transport. B. Presence of aquaporin channels for facilitated diffusion of water. C. Presence of a water pump. D. Presence of an ATP-driven enzyme for water transport. E. The presence of molecules that bind water and change its membrane permeability properties.

31. The movement of sucrose and H+ into the cell by the same membrane protein reflects the actions of what type of transporter?

A. voltage-gated channel. B. mechanosensitive channel. C. uniporte r. D. symport er. E. antiport er. 32. What process best characterizes Ca2+ movement from the cytosol (low Ca2+ concentration) into the endoplasmic reticulum (high Ca2+ concentration)?

A. Calcium movement is spontaneous. B. Calcium movement involves active transport. C. Calcium movement occurs by facilitated diffusion using a transporter protein. D. Calcium movement does not require energy. E. Calcium movement occurs by passive diffusion. 33. Acetylcholine binds this membrane protein, which subsequently opens to allow sodium to enter the cell. Acetylcholine exerts its effect on what type of transport protein?

A. ligand-gated channel B. voltage-gated channel C. mechanosensitive-gated channels D. regulatory protein-gated channels E. stretch-sensitive gated channels

34. Sodium concentrations are higher outside and glucose concentrations are higher inside the cell. Using the same membrane protein for Na+ and glucose transport, what is it called when a Na+ electrochemical gradient is used to drive glucose transport into the cell against its concentration gradient?

A. primary active transport B. secondary active transport C. primary facilitated diffusion D. secondary facilitated diffusion E. passive diffusion 35. ________ bind two or more ions or molecules and transport them in opposite directions across a membrane.

A. Uniporte rs B. Symporte rs C. Antiporte rs D. Dual transporters E. Channel pumps 36. The plasma membrane Na+/K+-ATPase pump

A. is used to generate sodium and potassium gradients across the membrane. B. is a symporter. C. is a pump for active transport of K+ out of the cell and Na+ into the cell. D. is a pump for facilitated diffusion of K+ into the cell and Na+ out of the cell. E. does not require ATP.

37. The release of the protein insulin from pancreatic cells occurs by

A. endocytosi s. B. pinocytosi s. C. phagocytosi s. D. exocytosi s. E. receptor-mediated endocytosis. 38. The process that most involves the selective uptake of a specific cargo molecule into the cell through receptor binding and aggregation is

A. pinocytosi s. B. receptor-mediated endocytosis. C. autophagocytos is. D. phagocytosi s. E. receptor-mediated exocytosis. 39. Plant cell membranes contain cholesterol. True

False

40. A protein is tightly associated with the plasma membrane but it can be isolated by treating the membrane with a strong detergent. What type of membrane protein is this?

A. A peripheral membrane protein B. An integral membrane protein C. Either an integral or a peripheral membrane protein D. Neither an integral nor a peripheral membrane protein

41. The presence of integral proteins allows membranes to be selectively permeable to certain molecules. True

False

42. Freeze fracture electron microscopy allows one to observe the two-dimensional cross section of membrane proteins. True

False

43. A researcher is studying the integral membrane protein "mysteriase" and chooses to perform an experiment similar to that performed by Frye and Edidin. The researcher fuses a mouse cell expressing mysteriase with a human cell. The fused cell is incubated at 37°C prior to being cooled to 0°C and labeled with a fluorescent antibody against mysteriase. When observed with a fluorescent microscope, mysteriase is observed to remain on one side of the fused cell. What is the most likely explanation for this surprising observation?

A. Mysteriase rigidifies the plasma membrane B. There is an error in the experimental procedure because this result is impossible C. Mysteriase is bound to the cytoskeletal filament D. Mouse cells are less fluid than human cells E. Mysteriase is a flippase enzyme that enhances lipid flip-flop rather than lipid lateral movement 44. Diffusion is the movement of a molecule from an area of high to low concentration. True

False

45. Osmosis describes the movement of water from an area of high to low solute concentration. True

False

46. Movement of molecules down their concentration gradient can drive the movement of a different molecule against its concentration gradient. True

False

47. Na+ ion concentrations are higher outside the cell than inside the cell. What type of transport system is required to move Na+ ions in and out of the cell?

A. Na+ moves into the cell by facilitated diffusion and out of the cell by active transport B. Na+ moves in and out of the cell by passive diffusion C. Na+ moves in and out of the cell by active transport D. Na+ moves into the cell by active transport and out of the cell by facilitated diffusion E. Na+ moves into the cell by facilitated diffusion and can not move out of the cell 48. The Na+/K+-ATPase pump is a ligand-gated ion channel. True

False

49. How does a macrophage (immune cell) consume a bacteria?

A. phagocytos is B. endocytos is C. exocytos is D. receptor-mediated endocytosis E. pinocytos is 50. Ion gradients across the membrane drive numerous cellular functions. True

False

51. A dysfunctional cell lacks a signal peptidase and is unable to cleave the ER signal sequence from proteins translated in the ER. What will be the effect on the cell's proteins?

A. The cell will have no integral membrane proteins B. All cellular proteins will have an ER signal sequence C. There will be a common signal sequence at the N-terminus of all integral membrane proteins in the plasma membrane D. All cellular proteins will become membrane proteins E. There will be a common signal sequence at the C-terminus of all integral membrane proteins in the nuclear envelope 52. A researcher is studying a culture of eukaryotic cells that shows an abnormal pattern of surface glycosylation. The researcher determines that these cells have normal levels of glycolipids and integral membrane proteins with O-linked glycosylation. The researcher discovers that there are no N-linked glycosylated proteins on the cell surface and measures unusually high levels of glycosylated dolichol in the ER membrane. What is a reasonable hypothesis to explain this observation?

A. The cell is defective in synthesizing of carbohydrates B. The cell is defective in assembling carbohydrate trees C. The cell has a defective oligosaccharide transferase D. The cell has a defect in its protein sorting pathway E. The cell has a defect in its ER localization signal 53. Imagine that a cell can be treated with a drug that prevents proteins from undergoing large conformational changes. Which transport proteins would be unaffected by this drug treatment? A. Na+/K+ ATPase B. H+/sucrose symporter C. Fructose uniporter D. Aquapori n E. All transport proteins would be affected

5 Key 1.

Two “magic” solutions are sold by a research supply company. “Magic Solution A” promises to extract all proteins, including integral membrane proteins, from the plasma membrane. “Magic Solution B” promises to simply extract all peripherally associated membrane proteins. What is the likely composition of “Magic Solution A” and “Magic Solution B”?

A. "Solution A" and "Solution B" both contain high salt buffers that disrupt hydrogen bonds and ionic interactions B. "Solution A" and "Solution B" both include membrane solubilizing detergent(s) C. "Solution A" is a membrane solubilizing detergent, "Solution B" is a high salt buffer that disrupts hydrogen bonds and ionic interactions D. "Solution A" is a high salt buffer that disrupts hydrogen bonds and ionic interactions, "Solution B" is a membrane solubilizing detergent Blooms Level: 4. Analyze Brooker - Chapter 05 #1 Gradable: automatic LO: 05.01.02 Identify the three different types of membrane proteins. Section: 05.01 Membrane Structure Topic: Cell Structure

2.

Cellular membranes are

A. flui d. B. solely composed of lipids. C. composed of a single layer of amphipathic molecules. D. selective to the transport of gases and small molecules only. E. found in eukaryotes, but not prokaryotes. Blooms Level: 1. Remember Brooker - Chapter 05 #2 Gradable: automatic LO: 05.01.01 Describe the fluid-mosaic model o...