Physioex 9.0
Review Sheet
Exercise 1
Cell Transport Mechanisms and Permeability
Name
Lab Time/Date ___
Activity 1 Simulating Dialysis (Simple Diffusion)
1. Describe two variables that affect the rate of diffusion. Size of material and concentration
2. Why do you think the urea was not able to diffuse through the 20 MWCO membrane? How well did the results compare with your prediction? The molecules were too large to pass through. This is what I predicted on my Hypothesis.
3. Describe the results of the attempts to diffuse glucose and albumin through the 200 MWCO membrane. How well did the results compare with your prediction? The glucose diffused through the 200 MCWO
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It increased the filtration rate because the blood pressure increased, but the concentration of solutes did not because the pore size did not increase.
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Activity 5 Simulating Active Transport
1. Describe the significance of using 9 mM sodium chloride inside the cell and 6 mM potassium chloride outside the cell, instead of other concentration ratios. The reason for the use of 9mM of sodium chloride is because 3 ions are ejected for every 2 K that are added. K hangs outside the cell unless actively transport inside the cell.
2. Explain why there was no sodium transport even though ATP was present. How well did the results compare with your prediction? There were no sodium ions because they were ejected by the cells by active transport.
3. Explain why the addition of glucose carriers had no effect on sodium or potassium transport. How well did the results compare with your prediction? The introduction of glucose had no effect on the sodium and potassium transport due to solute pumps.
4. Do you think glucose is being actively transported or transported by facilitated diffusion in this experiment? Explain your answer. The glucose is transported by facilitated diffusion in the experiment that is how glucose is transported. The glucose could not be actively transported because they are lipid insoluble and too large to pass through the membrane pores.
Lab Report 1
Activity 1
The purpose of this lab is to gain a better
13. Understand the transportation of potassium and sodium across plasma membranes. (p. 10 bottom right, p. 20 bottom right, p. 21 diagram)
3. Of the substances that diffused through the bag, did all of the molecules diffuse out? About half of the glucose did diffuse through the bag.
3. Explain your prediction for the effect Na+ Cl- might have on glucose transport. In other words, explain why you picked the choice that you did. How well did the results compare with your prediction?
Review Sheet Results 1. Explain the effect that increasing the Na+ Cl- concentration had on osmotic pressure and why it has this effect. How well did the results compare with your prediction? Your answer: The increase of the Na+Cl- concentration increased osmotic pressure the Na+ Cl- molecules diffused through the 50 mwco membranes and didn't go through the 20 mwco membranes. the more Na+Cl- we added to the 20 mwco membrane, the more the osmotic pressure went up. When I looked at my results I noticed when Na+Cl- was added to the 50 mwco membrane, there was no increase in osmotic pressure. This is becasue the Sodium chloride couldn't diffuse through the 50 mwco membranes. The higher concentration of molecues on one side of the mwco membrane forces the water movement to move to the side of greater solute concentration. 2. Describe one way in which osmosis is similar to simple diffusion and one way in which it is different. Your answer: Osmosis is similar to simple diffusion because both of these precesses have the passive transport characteristic. This is where particles in a solution move from an area of high solute concentration to an are of low solute concentration. Also neither of these processes need energy from an outside source to function. Osmosis is different than simple diffusion because in osmosis, if we have a selectively permeable membrane, this membrane is
2. Explain your observations in detail in terms of concentration gradient, diffusion, osmosis, osmotic pressure, passive transport, and active transport.
In this experiment, we will investigate the effect of solute concentration on osmosis. A semi‐permeable membrane (dialysis tubing) and sucrose will create an osmotic environment similar to that of a cell. Using different concentrations of sucrose (which is unable to cross the membrane) will allow us to examine the net movement of water across the membrane.
3. What would happen to the amount of H+ secreted into the renal tubule if the activity of the Na+ /K+
Explain the effect that increasing the Na+ Cl- concentration has on osmotic pressure and why it has this effect. How well did the results compare with your prediction?
Which materials diffused from the left beaker to the right beaker? NaCl, Urea, and Glucose at MWCO 200
When glucose carriers in the membrane were set to 500, the glucose transport rate for 2.00 mM of glucose was .0008 mM/min. Equilibrium was reached at 43 minutes. At 700 glucose carriers the rate was .0010 mM , and equilibrium was reached at 33 minutes. When the glucose carriers was set at 900 the rate was .012 mM/min, and equilibrium was reached at 27 minutes. After changing the glucose concentration to 8.0 mM, the glucose transport rate with 500 carrier proteins was .0023 mM/min, and equilibrium was reached at 58 minutes. With the simulation set at 700 carrier proteins the rate was .0031mM/min, and equilibrium was reached at 43 minutes. When the simulation was done with 900 carrier proteins the glucose transport rate was .0038, and equilibrium was reached at 35 minutes.
2. Explain why increasing extracellular K_ causes the membrane potential to change to a less negative value. How well did the results compare with your prediction? _______________________________________________________________________
The major objective of the experiment was to test the effect of the concentration gradient on the diffusion rate. It was hypothesized that the greater the stronger the concentration gradient, the faster the rate of diffusion would be. To test this, dialysis tubes were submerged in different concentration fructose solutions. We weighed the tubes at specific time intervals to measure the rate of diffusion of water in each different solution. The results illustrated that increased concentration gradient increases the rate of diffusion of water in the tubes. We concluded that as concentration of the
The data collected of % transmittance can then be used as an indication of changes in membrane permeability of
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?
The hypothesis states that if the solution is hypotonic the results will decrease, if the solution is hypertonic the results will increase and if the solution is isotonic the solution will vary and or remain constant. In order to test the predictions of the hypotonic, hypertonic, and isotonic hypothesis for the solution made during the study, four samples of sucrose were taken and placed into two different beakers each containing a different concentration. Then dialysis tubing A was placed into beaker 1 with B, C, and D placed into beaker 2 for 45 minutes and weighted at 15 minute intervals. My finding in the study was that each of the four samples changed from their initial weight and for the most part accurately proved the hypothesis.