Humany Anatomy & Physiology
Version 8.0
Physioex Exercise 1
CELL TRANSPORT MECHANISMS AND PERMEABILITY
Solute Transport Through Nonliving Membranes
Chart 1 - Dialysis Results (average diffusin rate in mM/min)
Solute 20 50 100 200
NaCL - .0150 .0150 .0150
Urea - - .0094 .0094
Albumin - - - -
Glucose - - - .0040
Which solute(s) were able to diffuse into the right beaker from the left?
a. NaCl, Urea, and Glucose
Which solute(s) did not difuse?
a. Albumin
If the solution in theleft 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?
a. @16 min @ 200 = 4.5 in both beakers
a. @16 min @ 100 = 4.5 in both beakers
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 that you removed the urea, but left the NaCL concentration unchanged? Hint: Assume that you also have control of the contents in the right beaker.
a. put 9mm of NaCl in the right beker - equals out the urea @ 100 mwco
Facilitated Diffusion
Chart 2 - Facilitated Diffusion Results (glucose transport rate, mM/min)
Glucose
Concentration
(mM) 500 700 900
2.00 .0008 .0010 .0012
8.0 .0023 .0031 .0038
What happened to the rate of facilitated diffusion as the number of protein carriers increased? Explain your answer.
a. rate of diffusion increased as rate of protein carriers increased.
What do you think would happen to the transport rate if you put the same concentration of glucose into both beakes instead of deionized wter in the right beaker?
a. solutions are equal - no transfer occurs
Should NaCL have an effect on glucose diffusion? Explain your answer. Use the simuation to see if it does.
a. No - rate of diffusion is the same with NaCl added - NaCl has no transport proteins to aid in diffusing glucose.
Simulating Osmotic Pressure
Do you see any evidence of pressure changes in either beaker, using any of the four membranes? If so, which membrane(s).
a. yes - the left beaker - increased pressure
Does NaCl appear in the right beaker? If so, which membrane(s) allowed it to pass?
a. yes - 50, 100, & 200
Chart 3 - Osmosis Results (pressuer in mm Hg)
Solute 20 50 100 200
NaCl 272 - - -
Albumin 153 153 153 153
Glucose 170 170 170 -
Explain the relationship between solute concentration and osmotic pressure.
a. if the solute concentration increases, the osmotic pressure increases.
Will osmotic pressure be generated if solutes are able to diffuse? Explain your answer.
a. No - if solutes diffuse, then the solutions will equalize
Because the albumin molecule is much 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.)
a. Nothing - they are equalized.
What would happen if you doubled the albumin concentration in the left beaker using any membrane?
a. pressure remained the same - no diffusion occurs
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.
a. Albumin pressure remained @ 153 but 5.00 of the glucose diffused to the albumin beaker.
What if you used the 100 MWCO membrane in the albumin/glucose run described in the previous question?
a. No diffusion - but pressure in the right beaker increased to 17 mmHg.
Simulating Filtration
Chart 4 - Filtration Results
Solute 20 50 100 200
Filtration Rate 1 2.5 5 10
NaCl in filtrate 0.00 4.80 4.81 4.81
NaCl membrane residue + + + +
Urea in filtrate 0.00 0.00 4.74 4.74
Urea membrane residue + + + +
Glucose in filtrate 0.00 0.00 0.00 4.39
Glucose in membrane + + + +
residue
Powdered Charcoal
in filtrate 0.00 0.00 0.00 0.00
in membrane residue + + + +
How did the membrane's MWCO affect the filtration rate?
a. the filtration rate increased as the solute # increased
Which solute did not appear in the filtrate using any of the membranes?
a. powdered charcoal
What would happen if you increased the driving pressure? Use the simulation to arrive at an answer.
a. the concentration remained the same but the filtrate rate increased.
Explain how you can increase the filtration rate t hrough living membranes.
a. increasing pressure increases filtration rate.
By examining the filtration results, we can predict that the molecular weight of glucose must be greater than 100 but less than 200.
Simulating Active Transport
Watch the solute concentration windows at the side of each beaker for any c hanges in Na and K concentrations. The Na transport rate stops before transport has completed. Why do you think that this happens?
a. the Na/K concentrate have equalized.
What would happen if you did not dispense anyt ATP?
a. no transport occurs
Has the amount of Na transported change?
a. yes - ATP @ 1 = 5.613
ATP @ 3 = .001
What would happen if you decreased the number of sodium-potassium pumps?
a. ATP @1 = 2.613
ATP @ 3 = no diffusion
As ATP decreases, diffusion decreases
Explain how you could show that phenomenon is not just simple diffusion. (Hint: Adjust the Na concentration in the right beaker.)
a. as ATP decreases, diffusion decreases
Click either Flush buttn to clean both beakers. Now repeat 1 through 6, dispensing 9.00 mM NaCl into the left beaker and 10.00 mM NaCl into the right beaker (instead of 6.00 mM KCl). Is Na transport affected by this change? Explain your answer.
a. ATP @1 = no transport
ATP @3 = no transport