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Vemtira Vemtira
wrote...
Posts: 9
Rep: 4 0
12 years ago
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



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Replies
wrote...
Valued Member
Educator
12 years ago
Are these answers to the questions? Hard to tell Face with Stuck-out Tongue
Vemtira Author
wrote...
12 years ago
Yes sorry, my first time to use this program and had a really tough time with it.  Every time I tried to put information in, the page would reboot.  Don't know if I can edit it and put on the title that they are the answers.  Can I?  Hopefully it will get easier to post in here.
wrote...
Donated
12 years ago
I have to write a scientific lab report on these experiments. No idea how to tie them together? Can't even come up with my intro or hypothesis! Any ideas?
wrote...
Staff Member
12 years ago
Can't even come up with my intro or hypothesis!

Well, what do you assume will happen? That's what a hypothesis is.
- Master of Science in Biology
- Bachelor of Science
Vemtira Author
wrote...
12 years ago
I agree with Duddy.  You can find posts with answers here, and that helps you out, but if you don't understand the process, then the answers are not going to do you any good in the long run.  You need to understand the processes of cell transport and membrane permeability, what can and cannot permeate the membrane.  Even though the answers are posted here, you must do the experiments and utilize the answers to help you get an understanding of what is happening.  Understanding this process is important for all the other chapters you will be studying throughout the semester.  If you don't get a basic understanding of this process, then you will struggle the entire semester, and further studies down the line.

If you have access to Mastering A & P, there are some really good videos that help you to understand the process.  Once you get an understanding of the processes, then you should be able to put this paper together. 

If you don't have access to Mastering A & P, there are videos posted on You Tube as well.

Good luck!
wrote...
Valued Member
Educator
12 years ago
If you don't have access to Mastering A & P, there are videos posted on You Tube as well.

Or you can request animations and we'll post them here.
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