Bio102 Problems Transport Across Membranes 1. Antiport is one type of A. facilitated transport. B. active transport. C. endocytosis. D. channel protein. E. carrier protein. 2. Pinocytosis is one type of A. exocytosis. B. phagocytosis. C. facilitated transport. D. endocytosis. E. diffusion. 3A. Consider a bacterial cell that is hypertonic in comparison to its environment. Will water move into the cell or out of the cell? 3B. We now add a large amount of either O2, N2, or Pyruvate to the fluid surrounding the cell. Which one will have the biggest effect on the movement of water? Will its addition increase or decrease the movement of water? Please explain your answer. 4. Imagine a bacterial cell living in a test tube under the following conditions: K+ Mg2+ Na+ inside the cell 50 mM 0.1 mM 10 mM outside the cell 10 mM 3 mM 150 mM 4A. Is the G value for Mg2+ movement into the cell positive, negative or zero? 4B. Under these conditions, is the solution hypotonic, hypertonic or isotonic relative to the cell? 4C. Under these conditions, will the net movement of water be into the cell or out of the cell? Why? 4D. If we added a large concentration (say, 1M) of CO2 to the outside of the cell, it would have no effect on the net movement of water. Why not? 4E. If the fatty acid tails in the phospholipids that make up this cell’s membranes were more saturated, would that increase or decrease the rate at which water moves? Or would it have no effect? Please explain. 5. Which one molecule might move across a membrane by simple diffusion? A. CO2 B. Glutamate (an amino acid) C. Insulin (a peptide hormone) D. K+ E. Maltose (a simple carbohydrate) 6. Which one statement does not accurately describe simple active transport? A. It requires a protein. B. Simple active transport is a type of endocytosis. C. Any type of substrate may be moved by simple active transport. D. ATP provides the energy for the movement. E. Simple active transport may be used to move a molecule against its concentration gradient. 7. A human liver cell is living in a a dish under the following conditions: + 2- - + Na SO4 Cl K outside the cell 100 mM 0.1 mM 15 mM 15 mM inside the cell 10 mM 100 mM 15 mM 150 mM Gin value: 7A. For each ion, indicate in the table whether the G value for the movement of that ion into the cell is positive (+), negative (-) or zero (0). 2- 7B. These cells use an antiporter protein to drive the uptake of SO4 into the cell. What other ion 2- might be co-transported along with SO4 ? Briefly describe how you arrived at your answer. 7C. Under these conditions, is the cell hypotonic, hypertonic or isotonic relative to the solution? 7D. Under these conditions, will the net movement of water be into the cell or out of the cell? 7E. If we added more cholesterol to this membrane, how would that affect the G values you described above? How would it affect whether the cell is hypertonic or hypotonic? How would it affect the rate at which the water moves? Or would it affect any of these? Please briefly explain your answer. 8. For each statement about membrane transport listed below, circle the type(s) of transport being described. Circle all that apply. Simple Facilitated Simple Active Coupled Active Can be used to transport amino acids. Diffusion Transport Transport Transport A sodium-magnesium symporter is an Simple Facilitated Simple Active Coupled Active example of this type of transport. Diffusion Transport Transport Transport This type of transport always requires a Simple Facilitated Simple Active Coupled Active protein. Diffusion Transport Transport Transport The transported molecule always follows Simple Facilitated Simple Active Coupled Active its concentration gradient. Diffusion Transport Transport Transport Simple Facilitated Simple Active Coupled Active Uses energy in ATP to move a molecule. Diffusion Transport Transport Transport Osmosis is one example of this type of Simple Facilitated Simple Active Coupled Active transport. Diffusion Transport Transport Transport CO2 waste is removed from the cell by Simple Facilitated Simple Active Coupled Active this type of transport Diffusion Transport Transport Transport 9. Match each statement to the type of transport being described. Notice that some statements may describe more than one type of transport; in those cases, list all that apply. Manganese ions could be moved by this type (or types) _______ of transport. The waste product of aerobic cell respiration is typically P Passive Transport _______ removed from the cell by this one type of transport. Some cells contain many copies of a Na+/Mn2+ F Facilitated Diffusion _______ antiporter. What type (or types) of transport is this? Increasing the number of unsaturations in the phospholipid tails would increase the rate of which one A Active Transport _______ type of transport? A channel protein may be used for this type (or types) of N None of the above _______ transport. 10. It’s not surprising that meat spoils quickly if left at room temperature for just a few days, due to the growth of a large number of bacteria. However, if that meat is first treated with large amounts of salt (making beef jerky), it can be left at room temperature indefinitely without spoiling. Why? 11. Which process is an example of endocytosis? A. Mitochondrial fission B. Antiport C. Oxidative phosphorylation D. Osmosis E. Pinocytosis 12. Imagine that we collect some white blood cells from a human donor and resuspend them in Phosphate-Buffered Saline (PBS). Under these conditions, the cells can live and be fully functional for several days. PBS consists of 10 mM sodium phosphate buffer at pH 7.4, 140 mM NaCl and 1M glucose and is isotonic to the cells. 12A. If we forgot to add any NaCl when preparing the PBS, what would happen to the white blood cells? Why? 12B. If we accidentally added 280mM NaCl while preparing the PBS, what would happen to the white blood cells? Why? 12C. After they have lived in the test tube for several hours, we are able to detect increasing concentrations of lactic acid in solutions surrounding these cells. What can you conclude about the metabolic state of these cells? Do you also expect these cells to be producing CO2? Please briefly explain your answers. 12D. What type of transport could be used by these cells to excrete the lactic acid? Please briefly explain your answer. 13. For each statement about membrane transport listed below, circle the type (or types) of transport being described. Circle all that apply. Molecular oxygen enters a cell by this Antiport Endocytosis Exocytosis Facilitated Transport type(s) of transport. Osmosis Simple Active Transport Simple Diffusion Symport Cotransport includes this type(s) of Antiport Endocytosis Exocytosis Facilitated Transport transport. Osmosis Simple Active Transport Simple Diffusion Symport Antiport Endocytosis Exocytosis Facilitated Transport Proteins made on the Rough ER are secreted by this mechanism(s). Osmosis Simple Active Transport Simple Diffusion Symport Antiport Endocytosis Exocytosis Facilitated Transport A carrier protein can be used for this type(s) of transport. Osmosis Simple Active Transport Simple Diffusion Symport Antiport Endocytosis Exocytosis Facilitated Transport ATP is cut in this type(s) of transport. Osmosis Simple Active Transport Simple Diffusion Symport .