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SHEET Lab REVIEW Report Lab 3 Addendum Cell Anatomy and Physioligy PhysioEx Worksheet Mark R. Graham 1455 Betty Court, Orange Park FL 32073 BSC2085C - Anatomy and Physiology I - 333738 Fall Term 2010 Larry Chad Winter lwinter@fscj.edu Submitted - 9/18/2010 NAME Mark Graham Cell Transport Mechanisms and Permeability Activity 1: Simulating Dialysis (Simple Diffusion) Chart 1 Dialysis Results |Membrane (MCWO) | |Solute | |20 |NaCl | |0.0000 |0.0150 |0.0150 |0.0150 |Urea | |0.0000 |0.0000 |0.0094 |0.0094 |Albumin |0.0000 |50 |100 |0.0000 |200 |0.0000 | 0.0000 |Glucose 0.0040 | |0.0000 |0.0000 |0.0000 | | Which solute(s) were able to diffuse into the right beaker from the left? Na+/Cl- , Urea, Glucose Which solute(s) did not diffuse? Albumin If the solution in the left beaker contained both urea and albumin, which membrane(s) could you choose to selectively remove the urea from the solution in the left beaker? 100 MCWO and 200 MCWO Assume that the solution in the left beaker contained NaCl in addition to the urea and albumin. How could you set up an experiment so that you removed the urea, but left the NaCl concentration unchanged? Put a solution in the right beaker with no urea and the same concentration of NaCl as the left beaker while using a 100 or 200 MCWO membrane between the two beakers. A c t i v i t y 2: Simulating Facilitated Diffusion Chart 2 Facilitated Diffusion Results |Glucose Concentration (mM) | | | |500 |Number of glucose carrier proteins |700 |900 |2.00 | |0.0150 |0.0150 |0.0150 |8.00 | |0.0025 |0.0034 |0.0042 What happened to the rate of facilitated diffusion as the number of protein carriers increased? Explain your answer. The rate of facilitated diffusion of glucose molecules increased and the time needed to reach equilibrium decreased with the successive increases of glucose carrier proteins placed in the membranes used in the experiments recorded above. This means that glucose carrier proteins assist in speeding up the diffusion of glucose across a permeable membrane. What do you think would happen to the transport rate if you put the same concentration of glucose into both beakers instead of deionized water in the right beaker? The transport rate would be equal in both directions meaning the solutions would be at equilibrium. Should NaCl have an effect on glucose diffusion? Explain your answer. Use the simulation to see if it does. The sodium and chloride ions should have no impact on the diffusion of glucose through the membrane. The simulation proves this to be true no matter how many glucose carriers are in the membrane or how high the concentration of NaCl is in either beaker. The membrane is loaded with proteins that assist in the diffusion of only glucose. A c t i v i t y 3 : Simulating Osmotic Pressure Do you see any evidence of pressure changes in either beaker, using any of the four membranes? If so, which ones? Pressure changes in the left beaker when using all four membranes. The pressure changed the most using the 20 MWCO membrane and the least using the 200 MWCO membrane. Does NaCl appear in the right beaker? If so, which membrane(s) allowed it to pass? The 50, 100 and 200 MWCO membranes allow NaCl to pass from the left beaker into the right beaker. Chart 3 Osmosis Results (pressure in mm Hg) |Membrane (MWCO) | |Solute |20 |50 |100 |200 | |Na+Cl| |306 |---- |---- |---- |Albumin | |153 |153 |153 |153 |Glucose | |153 |153 |153 |---- Explain the relationship between solute concentration and osmotic pressure. The higher the solute concentration, the higher the osmotic pressure becomes because the higher the solute concentration , the more water moves through the membrane by osmosis to dilute the solution. Will osmotic pressure be generated if solutes are able to diffuse? Explain your answer. If all solutes are able to diffuse through the membrane, there will be no osmosis because the solutes will reach equilibrium of concentrations on both sides of the membrane or the solutions will become isotonic, thereby stopping any osmosis. Because the albumin molecule is much too large to pass through a 100 MWCO membrane, you should have noticed the development of osmotic pressure in the left beaker in the albumin run using the 100 MWCO membrane. What do you think would happen to the osmotic pressure if you replaced the deionized water in the right beaker with 9.00 mMalbumin in that run? (Both beakers would contain 9.00 mM albumin.) The solutions would be isotonic and no osmotic pressure would develop. What would happen if you doubled the albumin concentration in the left beaker, using any membrane? The osmotic pressure would double as well. In the albumin run using the 200 MWCO membrane, what would happen to the osmotic pressure if you put 10 mM glucose in the right beaker instead of deionized water? Explain your answer. The osmotic pressure is the left beaker would rise to the same pressure as without using any glucose at all because the 200 MWCO membrane allows the glucose to diffuse through it to create equilibrium of glucose solutes but does not allow any albumin to diffuse creating osmotic pressure while trying to dilute the albumin solution. What would happen if you used the 100 MWCO membrane in the albumin/glucose run described in the previous question? The osmotic pressure would rise in the right beaker because no solute would be able to diffuse through the membrane and the higher concentration of glucose on the right would cause the water to move toward it by osmosis. A c t i v i t y 4: Simulating Filtration Chart 4 Filtration Results (Filtration Rate, Solute Presence or Absence) |Membrane (MWCO) | | | | Solute |10 ml/min |NaCl | | Present |Urea | | Present |Glucose | | Present |20 Rate |50 |1.0 ml/min |100 |200 |2.5 ml/min |5 ml/min | |Filtrate |Residue | |8.66 |Present |Filtrate |Residue | |0.00 |Residue | |0.00 |Present |0.00 |8.66 |Present |4.74 |Present |0.00 |Present |Filtrate |8.66 |0.00 |Present |Filtrate |Powdered Charcoal |0.00 | |0.00 |4.74 |Present |0.00 |Present |0.00 | | |4.39 |Present |0.00 | | Present |Residue | |Present |Present |Present | Did the membranes MWCO affect the filtration rate? Yes. It affected whether it could be filtered or not but once the minimum MWCO size for the filtrate to pass through the membrane was reached, increasing the size of the MWCO had no effect on the filtration rate. Which solute did not appear in the filtrate using any of the membranes? Powdered charcoal. What would happen if you increased the driving pressure? Use the simulation to arrive at an answer. The speed of filtration increases. Explain how you can increase the filtration rate through living membranes. By increasing the pressure behind the solution to be filtered such as an increase in blood pressure. By examining the filtration results, we can predict that the molecular weight of glucose must be greater than ___100__but less than ____200__. A c t i v i t y 5 : Simulating Active Transport Watch the solute concentration windows at the side of each beaker for any changes in Na+ and K+ concentrations. The Na+ transport rate stops before transport has completed. Why do you think that this happens? Because the ATP gets used up before transport is completed. What would happen if you did not dispense any ATP? No facilitated diffusion would place take because an energy soured like ATP is necessary for it to take place. Click either Flush button to clean both beakers. Repeat steps 3 through 6, adjusting the ATP concentration to 3.00 mM in step 5. Click Record Data after each run. Has the amount of Na+ transported changed? The amount of NaCl transported has not changed. What would happen if you decreased the number of sodium/potassium pumps? Nothing will happen if there is no KCl added to the right beaker. If KCl is added to the right beaker and ATP is dispensed then the rate of transport will slow down and the ATP will last longer. Explain how you could show that this phenomenon is not just simple diffusion. (Hint: Adjust the Na+ concentration in the right beaker.) The transfer of Na+ ions will go up its concentration gradient which will not happen in simple diffusion. Click either Flush button to clean both beakers. Now repeat steps 1 through 6, dispensing 9.00 mM NaCl into the left beaker and 10.00 mM NaCl into the right beaker (instead of 6.00 mM KCl). Is Na_ transport affected by this change? Explain your answer. The Na+ transport is not affected because no transport takes place unless there are K+ ions to make the Na+/K+ pumps work. What would happen to the rate of ion transport if we increased the number of sodium-potassium pump proteins? If there were Na and K ions on opposite sides of the membrane and ATP was dispensed and the number of sodium-potassium pump proteins were increased then the rate of ion transport would increase. If there was only NaCl on each side of the membrane then nothing would happen. Would Na_ and K_ transport change if we added glucose solution? The addition of glucose to the solution will not affect the transport of Na and K because the Na+/K+ pumps only work on Na and K. Review Questions Highlight all answers that apply to questions 1 and 2. 1. Differential permeability: a. is also called selective permeability b. refers to the ability of the plasma membrane to select what passes through it c. implies that all substances pass through membranes without hindrance d. keeps wastes inside the cell and nutrients outside the cell 2. Passive transport includes a. osmosis b. simple diffusion c. bulk-phase endocytosis d. pinocytosis e. facilitated diffusion 3. The following refer to the dialysis simulation. Did the 20 MWCO membrane exclude any solute(s)? Yes. All of them. Which solute(s) passed through the 100 MWCO membrane? NaCl and urea. Which solute exhibited the highest diffusion rate through the 100 MWCO membrane? NaCl. Explain why this is so. It has the smallest molecular weight and smaller particles move faster. 4. The following refer to the facilitated diffusion simulation. Are substances able to travel against their concentration gradient? Yes. If there is ATP and there are carrier proteins available. Name two ways to increase the rate of glucose transport. Increase the concentration of the glucose in the solution and increase the nimmber of glucose carrier molecules. Did NaCl affect glucose transport? No. It did not affect the glucose transport rate. Does NaCl require a transport protein for diffusion? No. It moves by simple diffusion. 5. The following refer to the osmosis simulation. Does osmosis require energy? No. Is water excluded by any of the dialysis membranes? No. Is osmotic pressure generated if solutes freely diffuse? No. Explain how solute concentration affects osmotic pressure. The higher the concentration of solutes, the higher the resulting osmotic pressure. 6. The following refer to the filtration simulation. What does the simulated filtration membrane represent in a living organism? Cardiovascular system capillaries and kidney tubules. What characteristic of a solute determines whether or not it passes through a filtration membrane? The size of the particles. Would filtration occur if we equalized the pressure on both sides of a filtration membrane? No. 7. The following questions refer to the active transport simulation. Does the presence of glucose carrier proteins affect Na_ transport? No. Can Na_ be transported against its concentration gradient? Yes. If there are pump proteins and ATP available. Are Na_ and K_ transported in the same direction? No. Opposite directions. The ratio of Na_ to K_ transport is Na_ transported out of the cell for every K_ transported into the cell. 3 Na ions transported out to every 2 K ions transported into the cell. 8. What single characteristic of the differentially permeable membranes used in the simple diffusion and filtration experiments determines which substances pass through them? The size of the holes in the membrane. In addition to this characteristic, what other factors influence the passage of substances through living membranes? The concentration of the solutes in the solutions, the amount of energy releasing substances available, the number of transport molecules in the membranes and the amount of pressure exerted on the membrane. 9. Assume that you have two beakers of solution separated by a semipermeable membrane. The left beaker contains 4 mM NaCl, 9 mM glucose, and 10 mM albumin. The right beaker contains 10 mM NaCl, 10 mM glucose, and 40 mM albumin. The dialysis membrane is permeable to all substances except albumin. State whether each substance (a) will move to the right beaker, (b) will move to the left beaker, or (c) will not move. b______Glucose c______Albumin a______Water b______NaCl 10. When food is pickled for human consumption, as much water as possible is removed from the food. What method is used to achieve this dehydrating effect? The food is place into a hypertonic solution of vinegar and salt. 11. What determines whether a transport process is active or passive? If it requires the use of energy to move the particles across the membrane, it is active and if it does not , it is passive. 12. Characterize passive and active transport as fully as possible by choosing all the phrases that apply and inserting their letters on the answer blanks. Passive transport: a, c, e. Active transport: b ,d, f. a. accounts for the movement of fats and respiratory gases through the plasma membrane b. explains solute pumping, bulk-phase endocytosis, and pinocytosis c. includes osmosis, simple diffusion, and filtration d. may occur against concentration and/or electrical gradients e. uses hydrostatic pressure or molecular energy as the driving force f. moves ions, amino acids, and some sugars across the plasma membrane 13. Define the following terms. diffusion: The spreading of particles in a gas or solution with a movement toward uniform distribution of particles;driven by kinetic energy. osmosis: Diffusion of a solvent through a membrane from a dilute solution to a concentrated solution. simple diffusion: The unassisted transport across a membrane of a lipid soluble substance or a very small particle. filtration: Passage of a solvent and dissolved substances through a membrane or filter. active transport: The process of transporting substances across a membrane requiring ATP. bulk-phase endocytosis: The process of an endocytotic vesicle forming around a small volume of extracellular fluid and the substance within it during phagocytosis. pinocytosis: Engulfing of extracellular fluids by a cell. facilitated diffusion: Passive transport of certain molecules through carrier proteins or channels across a plasma membrane. ... View Full Document

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