Simple Diffusion Activity 1: Simulating Simple diffusion
1.What is the molecular weight of Na+? 22.9 2. What is the molecular weight of Cl-? 35.45 3. Which MWCO dialysis membranes allowed both of these ions through? 50, 100, and 200 4. Which materials diffused from the left beaker to the right beaker? Urea, NaCl and glucose diffused 5. Which did not? Why? Albumin, because the molecular weight exceeded the highest MWCO membrane, thus being to large to pass through
Activity 2: Simulating Dialysis
1. What happens to the urea concentration in the left beaker (the patient)? It is reduced to 50% travels to the right beaker and reaches equilibrium at 17 minutes 2. Why does this occur? Because the more concentrated it became it causes the molecules to move down
Facilitated Diffusion Activity 3: Facilitated Diffusion 1. At a given glucose concentration, how does the amount of time it takes to reach equilibrium change with the number of carriers used to “build” the membranes? The higher number of carriers the quicker it reaches equilibrium 2. Does the diffusion rate of Na+/Cl- change with the number of receptors? No 3. What is the mechanism of the Na+/Cl- transport? Plasma vessels Look at #2 above; it’s simple diffusion because there is no change in diffusion rate with the number of receptors. The glucose that’s actively transported not the salt. If it did the amount of NaCl transported would increase with the number of receptors. The receptors are specific for glucose. -2.5pts
4. If you put the same amount of glucose in the right beaker as in the left, would you be able to observe any diffusion? No 5. Does being unable to observe diffusion necessarily mean that diffusion is not taking place? No
Osmosis Activity 4: Osmosis
1. Did you observe any pressure changes during the experiment? If so, in which beaker(s), and with which membranes? Yes in the Left beaker with the 20 MWCO Membrane because the pressure went up 2. Why? Because no diffusion took place 3. Did the Na+/Cl-diffuse from the left beaker to the right beaker? If so, with which membrane(s)? Yes, 50,100, and 200 MWCO 4. Why? Because diffusion took place 5. Explain the relationship between solute concentration and osmotic pressure? They are directly proportional, if the solute concentration increases the osmotic pressure will increase. 6. Does diffusion allow osmotic pressure to be generated? No 7. Would pressure be generated if solute concentrations were equal on both sides of the membrane? No it does not generate 8. Why or why not? They are isotonic, they do not contribute to the tonicity of a solution as they pass through 9. Would pressure be generated if you had 9 mM glucose on one side of a 200 MWCO membrane and 9 mM NaCl on the other side? If so, which solution was generating the pressure? No 10. Would pressure be generated if you had 9 mM albumin on one side of a 200 MWCO membrane and 9 mM NaCl on the other side? If so, which solution was generating the pressure? Yes the albumin
Filtration Activity 5: Filtration
1. What were the results of your initial membrane analysis? The concentration in filtrate was 0 for all and the membrane residue analysis showed all were present 2. Does the membrane MWCO affect filtration rate? Yes 3. Does the amount of pressure applied affect the filtration rate? No 4. Did all solutes pass through all the membranes? There were traces of the powdered charcoal on the residue analysis, but the charcoal did not show up on the concentration I would have to say yes and no 5. If not, which one(s) did not? Charcoal 6. Why? The sizes of the pores 7. How can the body selectively increase the filtration rate of a given organ or organ system? By increasing blood vessel radius to increase fluid flow and thus pressure in the vessel going to a given organ
Active Transport Activity 6:Active Transport
1. At the end of this experimental run, did the Na+/Cl- move from the left vessel to the right vessel? No 2. Why? No potassium present 3. As the run progresses, the concentrations of the solutes will change in the windows next to the two beakers. The rate will slow down markedly, then stop before completed. Why? The rate of Active Transport decreases 4. Does the amount of NaCl/KCl transported change? Yes 5. Does the amount of solute transported across the membrane change with an increase in carriers or pumps? Yes 6. Is one solute more affected than the other? No both are equal 7. Does the membrane you “built” allow simple diffusion? Yes 8. If you placed 9 mM NaCl on one side of the membrane and 15 mM on the other side, would there be movement of the NaCl? Why? No because like in #2 above there is no potassium present. The Na+/K+ pump requires both a sodium and potassium presence on opposite sides of the membrane
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