Lab 1 – Cell Transport Mechanisms and Permeability (p. 1)
Introduction:
In this lab, I will study different ways in which substances move across the plasma membrane and what type of force is necessary for each mechanism. I will define Key Terms that describe what will occur in the experiments; I will conduct an experiment for each Activity and provide all resulting Data as well as answer Questions from each Activity. I will then provide a short Summary for what I learned in each Activity.
Key Terms: ?define each term (from lab manual pgs. given/supporting materials)
Concentration Gradient (p. 1) -
Diffusion (p. 1) -
Simple Diffusion (p. 2) -
Osmosis (p. 2,4) -
Facilitated Diffusion (p. 4) -
Filtration (p. 7) -
Active Transport (p. 9) -
Solute Pumps (p. 10) -
Pinocytosis (p. 10) -
Phagocytosis (p. 10) -
Activity 1: Simulating Dialysis (Simple Diffusion)
Data:
Chart 1 – Dialysis Results (average diffusion rate in mM/min)
Solute Membrane (MWCO)
20 50 100 200
NaCl (add your results here; numbers OR “—“ for zero diffusion; RATE not time!)
Urea
Albumin
Glucose
Questions: ?answer each question; use full sentences; ask instructor if you need help
1-1: Which solute(s) were able to diffuse into the right beaker from the left?
1-2: Which solute(s) did not diffuse?
1-3: 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?
How would you carry out this experiment?
1-4: 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 you removed the urea, but left the NaCl concentration unchanged? Hint: Assume that you also have control of the contents in the right beaker.
Summary:
In this Activity, I learned/observed that: ? write 1-2 sentences on what you observed by doing this experiment – think “big picture”
Activity 2: Simulating Facilitated Diffusion
Data:
Chart 2 – Facilitated Diffusion Results (glucose transport rate, mM/min)
Glucose Conc. No. of glucose carrier proteins
(mM) 500 700 900
2.00 (add your results here; numbers OR “—“ for zero diffusion; RATE not time!)
8.00
Questions: ?answer each question; use full sentences; ask instructor if you need help
2-1: What happened to the rate of facilitated diffusion as the number of protein carriers increased? Explain your answer.
2-2: 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?
2-3: Should NaCl have an effect on glucose diffusion? Explain your answer. Use the simulation to see if it does.
Summary:
In this Activity, I learned/observed that: ? write 1-2 sentences on what you observed by doing this experiment – think “big picture”
Activity 3: Simulating Osmotic Pressure
Data:
Chart 3 - Osmosis Results (pressure in mm Hg)
Solute Membrane (MWCO)
20 50 100 200
NaCl (add your results here; numbers OR “—“ for zero diffusion; PRESSURE)
Albumin
Glucose
Questions: ?answer each question; use full sentences; ask instructor if you need help
3-1: Do you see any evidence of pressure changes in either beaker, using any of the four membranes? If so, which membrane(s)?
3-2: Does NaCl appear in the right beaker? If so, which membrane(s) allowed it to pass?
3-3: Explain the relationship between solute concentration and osmotic pressure.
3-4: Will osmotic pressure be generated if solutes are able to diffuse? Explain your answer.
3-5: Because the albumin molecule is 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 mM albumin in that run? (Both beakers would contain 9.00 mM albumin).
3-6: What would happen if you doubled the albumin concentration in the left beaker using any membrane?
3-7: 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.
3-8: What if you used the 100 MWCO membrane in the albumin/glucose run described in the previous question?
Summary:
In this Activity, I learned/observed that: ? write 1-2 sentences on what you observed by doing this experiment – think “big picture”
Activity 4: Simulating Filtration
Data:
Chart 4 – Filtration Results
Solute Membrane (MWCO)
20 50 100 200
Filtration rate (ml/min) (add your results here; numbers OR +/-)
NaCl in filtrate (mg/ml)
NaCl membrane residue (+/-)
Urea in filtrate (mg/ml)
Urea membrane residue (+/-)
Glucose in filtrate (mg/ml)
Glucose membrane residue (+/-)
Powdered charcoal in filtrate (mg/ml)
Powdered charcoal membrane residue (+/-)
Questions: ?answer each question; use full sentences; ask instructor if you need help
4-1: How did the membrane's MWCO affect the filtration rate? A smaller membrane MWCO (size) causes _______________ (less, more, equal - choose one) filtration rate than a larger membrane MWCO.
4-2: Which solute did not appear in the filtrate using any of the membranes?
4-3: What would happen if you increased the driving pressure? Use the simulation to arrive at an answer. When I increased the driving pressure, filtration _______________ (increased, decreased, stayed the same - choose one).
4-4: Explain how you can increase the filtration rate through living membranes.
4-5: By examining filtration results, we can predict that the molecular weight of glucose must be greater than ____________ but less than _______________. (Hint: answer refers to solutes and NOT MWCOs).
Summary:
In this Activity, I learned/observed that: ? write 1-2 sentences on what you observed by doing this experiment – think “big picture”
Activity 5: Simulating Active Transport
Data: ?No chart necessary here, but you will need to use the data you get from running the experiments to answer the questions below
Questions: ?answer each question; use full sentences; ask instructor if you need help
5-1: 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? Hint: think about what is necessary for active transport to occur.
5-2: What would happen if you did not dispense any ATP?
5-3: Has the amount of Na+ transported changed?
5-4: What would happen if you decreased the number of sodium-potassium pumps?
5-5: Explain how you could show that this phenomenon is not just simple diffusion. (Hint: Adjust the Na+ concentration in the right beaker).
5-6: Is Na+ transport affected by this change? Explain your answer.
5-7: What would happen to the rate of ion transport if we increased the number of sodium-potassium pump proteins?
5-8: Would Na+ and K+ transport change if we added glucose solution?
Summary:
In this Activity, I learned/observed that: ? write 1-2 sentences on what you observed by doing this experiment – think “big picture”
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