Exercise 1 Essay
Did any solutes move through the 20 MWCO membrane? Why or Why not? 2. Did Na+Cl- move through the 50 MWCO membrane? Activity 2: 1. Are the solutes moving with or against their concentration gradient in facilitated diffusion? 2. What happened to the rate of facilitated diffusion when the number of carrier proteins was increased? 3. In the simulation you added Na+Cl- to test its effect on glucose diffusion. Explain why there was no effect. Activity 3: 1. Which membrane resulted in the greatest pressure with Na+Cl- as the solute?
Why? 2. Explain what happens to the osmotic pressure with increasing solute concentration. 3. If the solutes are allowed to diffuse, is osmotic pressure generated? 4. If the solute concentrations are equal, is osmotic pressure generated? Why or Why not? Activity 5: 1. In the initial trial the number of Na+ -K+ pumps is set to 500, the Na+Cl- concentration is set to 9. 00mM, the K+Cl- concentration is set to 6. 00mM, and the ATP concentration is set to 1. 00mM. Explain what happened and why. What would happen if no ATP had been dispensed? . Why was there no transport when you dispensed only Na+Cl-, even though ATP was present? 3. What happens to the rate of transport of Na+ and K+ when you increase the number of Na+ -K+ pumps? 4. Explain why the Na+ and K+ transports were inaffected by the addition of glucose. Exercise 1: Cell Transport Mechanisms and Permeability: Activity 1: Simulating Dialysis (Simple Diffusion) Lab Report Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1. The driving force for diffusion is You correctly answered: b. he kinetic energy of the molecules in motion. 2. In diffusion, molecules move You correctly answered: a. from high concentration to low concentration. 3. Which of the following dialysis membranes has the largest pore size? You correctly answered: d. 200 MWCO 4. Avogadro’s number is a constant for the number of You correctly answered: b. molecules. Experiment Results Predict Question: Predict Question 1: The molecular weight of urea is 60. 07. Do you think urea will diffuse through the 20 MWCO membrane? Your answer : c. No, not at all.
Predict Question 2: Recall that glucose is a monosaccharide, albumin is a protein with 607 amino acids, and the average molecular weight of a single amino acid is 135 g/mole. Which of the following will be able to diffuse through the 200 MWCO membrane? Your answer : c. glucose only Stop & Think Questions: The reason sodium chloride didn’t diffuse left to right is that You correctly answered: c. the membrane pore size was too small. Glucose is a six-carbon sugar. Albumin is a protein with 607 amino acids. The average molecular weight of a single amino acid is 135 g/mole.
There is no reason to run these solutes at the 20 MWCO because You correctly answered: d. glucose and albumin are both too large to pass. The rate of diffusion for urea You correctly answered: b. is slower than that for sodium because urea is a larger molecule. Experiment Data: Solute Na+ ClUrea Na+ ClNa+ ClNa+ ClUrea Glucose Albumin MWCO 20 20 50 50 100 100 200 200 Solute Concentration 9. 00 9. 00 9. 00 18. 00 9. 00 9. 00 9. 00 9. 00 Average Diffusion Rate 0. 0000 0. 0000 0. 0150 0. 0300 0. 0150 0. 0094 0. 0040 0. 0000 Post-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. . The effect of increasing the concentration of sodium chloride from 9 mM to 18 mM in the left beaker was to You correctly answered: b. increase the rate of diffusion. 2. Describe the difference between the rate of diffusion seen for sodium and urea. You correctly answered: c. Urea diffused more slowly because it is larger than sodium. 3. Which of the following solutes did not pass through any of the membranes? You correctly answered: b. albumin 4. When diffusion stops, we say the solution has reached You correctly answered: a. equilibrium.