Rate of diffusion

Ross Koning Koning at ECSUC.CTSTATEU.EDU
Mon Nov 4 08:45:44 EST 1996


At  8:39 AM 11/4/96 +0000, Paul Clark wrote:
>I am doing an Investigation on the rate which diffusion occurs in a
>living cell.  I was woundering if any one had any idears on the
>experiment.  I have already looked on the World Wide Wide but, it's
>mainly people talking about university lectures and talking in a
>language of university standard biological terms  which seem's to be
>a foreign language, without further expaination.
>
>I understand the basic principles of Ficks's law and the factors that
>effect the experiment although, I'm am still unable to decide on an
>experiment to prove these factors.
>
>I have found this experiment already although it has a limitation
>with the measuring the diffusion rate, and it would not produce a set
>of results very easily.
>
>By dissolving gelatin the unfairness supplied by the loose molecule
>structure of water is reduced.   10 grams of gelatin is dissolved in
>100 grams of hot water and the solution is poured into test tubes to
>half fill them.  2 grams of the gelatin is coloured with methylene
>blue and as soon as the first layer of gelatin is set firmly, a
>narrow layer of blue gelatin is poured on to it.  When the blue layer
>have set the rest of the clear gelatin and cooled quickly.  The blue
>methylened gelatin is sandwiched between the two layers of clear gelatin.
>Thanking you in advance

Your idea sounds fine...I think you are going in the right
direction to think about turbulent flow in water.  The gel
helps prevent/slow that.  The problem I see is that many
dyes are attracted and bind to proteins.  Thus the movement
of the blue color might be slowed by this kind of binding.
We have tried to use agar in test tubes...the problem we had
was that there is generally a layer of free water on the
surface and this "communicates" down the sides of the tube.

In any case, the reduction of turbulent flow by using a
gel is very instructive...particularly if you also try a
free-water control!

ross

______________________________________________________________
                            |
Ross Koning                 | Koning at ecsu.ctstateu.edu
Biology Department          | http://koning.ecsu.ctstateu.edu/
Eastern CT State University | Phone: 860-465-5327
Willimantic, CT  06226  USA | Fax: 860-465-5213
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                Plant Physiology is Phun!

 /\|___/\     //\______COOH   NH-CH2-CH=C-CH2OH  \/OH
|  |  |  |    |  |  ||       //\___     \CH3     /\|/\\/\\COOH
 \/ \/|\/|    \\/ \ /       N  ||  N            |  |
 /\ | |__|=        NH       |  || ||           //\//\
  | COOH                    \\ /\ /            O
  COOH        H2C=CH2         N  NH
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