SMeissne at AOL.COM SMeissne at AOL.COM
Thu Sep 30 20:12:27 EST 1999

If you want to show selective membrane permeability in a visual
manner try this:

Take some Rhoeo discolor leaves.  Get sections of the upper half
of the leaf and float on a solution of a weak acid and other sections
on a solution of a weak base.  The pigments in this plant change
color with change in pH, and entry of a weak organic acid or a weak base 
such as ammonium, over 
a few minutes there should be a noticeable change in their color.  You 
can compare the affect of a strong acid or base (such as NaOH or HCl)
which is too polar to cross the membrane easily.  

Scott T. Meissner

Aure Entuluva!

In a message dated 99-09-30 09:47:33 EDT, you write:

 good morning, plant-edders.
 does anybody know of software that simulates the movement of 
 molecules through cell membrane? my nonmajors class is having a 
 very hard time with the fluid mosaic model, and i have the idea that 
 simulating the passage of molecules, along with making flubber 
 mosaics in lab, might help.
 any ideas will be appreciated.

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