teaching electrophoresis to freshmen
David L. Robinson
dlrobi02 at HOMER.LOUISVILLE.EDU
Mon Jun 17 18:24:32 EST 1996
I am currently developing the laboratory component of a freshman,
introductory biology class (for majors) that I teach in the fall.
I want to demonstrate electrophoresis in lab, and am trying to
figure out the most effective way to do it. Does anyone have any
I know I could do a demonstration SDS-protein gel showing the protein
profiles of different species/tissues, or I could do lambda
restriction digests and run a DNA gel, but: 1) I only have 3 hours per
lab period for each group of students, 2) I teach multiple sections so this
would be really a strain in terms of time and expense, 3) I'd rather not
have a bunch of 18-year-olds playing around with things like acrylamide,
ethidium bromide, etc. 4) I could just as easily show publication-quality
photos of protein or DNA gels that are already in the literature
or textbooks....what I really want them to appreciate is the *concept*
of electrophoresis.....that you can separate molecules based on their
size, charge and shape using an electric field. Once they understand
that then they can start to deal with actual protein/DNA/RNA gels.
Last year, after I had them do paper chromatography exercises in
separating chlorophyll and then amino acids I was able to just say that
electrophoresis was "sort of like that except.....la la la". But I am
not sure paper chromatography is conceptually a real good analogy for
electrophoresis! Plus, I would like them to at least *see* some of the basic
equipment that is used in cellular/molecular biology even if they don't get
to actually use it themselves.
Now my idea is to pour an agarose gel for them, and load a well with
a single, dark solution that would be a mixture of different dyes and then
apply current. The dyes would move at different rates and
separate out. In my imagination they would see lots of bands of red, blue,
green, etc that had been separated by electric force. That would be the
end of it...without any other steps I would have demonstrated the basic
process of electrophoresis. Comments?????
Does anyone have any good ideas for what dyes would be good for this?
I can use bromophenol blue and xylene cyanole as they are different in
color and mobility in an agarose system.....what other dyes of different
color and mobility can I add to this mixture?
Thanks for any advice.
Dave Lowell Robinson dlrobi02 at homer.louisville.edu
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