Cell Transport Mechanisms and Permeability Essay

929 WordsMar 6, 20134 Pages
Physioex 9.0 Review Sheet Exercise 1 Cell Transport Mechanisms and Permeability Name: Tiffani Hernandez Lab Time/Date: 12pm / January 23, 2013 Activity 1 Simulating Dialysis (Simple Diffusion) 1. Describe two variables that affect the rate of diffusion: Molecular Weight and Size affect the rate of diffusion. 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? Urea was too large to diffuse through the 20 MWCO membrane because its molecular weight is about 60. I predicted that urea would not be able to pass through. 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? Glucose was able to diffuse through the 200 MWCO because its molecular weight is 180. Albumin was not able to diffuse because its molecular weight is much larger than 200. 4. Put the following in order from smallest to largest molecular weight: glucose, sodium chloride, albumin, and urea. NaCl, Urea, Glucose, Albumin. Activity 2 Simulated Facilitated Diffusion 1. Explain one way in which facilitated diffusion is the same as simple diffusion and one way in which it differs. molecules move from a higher concentration to a lower concentration in both processes. However, facilitated diffusion uses protein carrier molecules to allow substances to diffuse through the cell membrane, while simple diffusion does not require an input of energy. 2. The larger value obtained when more glucose carriers were present corresponds to an increase in the rate of glucose transport. Explain why the rate increased. How well did the results compare with your prediction? The rate increased because there were more glucose carriers to transport more glucose across the membrane. 3. Explain your prediction for the
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