From: David Lauter (djlauter@hotmail.com)
Date: Sun Nov 30 2003 - 21:09:28 PST
From: "David Lauter" <djlauter@hotmail.com> Subject: Re: Pinhole Digest #1378 - 11/30/03 Date: Sun, 30 Nov 2003 21:09:28 -0800 Message-ID: <Law15-F56xc1o8yfogk000258c3@hotmail.com>
For you biophysicists out there, last week we excited some chlorophyll.
This was my first attempt at this very simple demonstration so I would like
some explanation that is better than my biology text. A chlorophyll mixture
was made by filtering a suspension of leaves that had been ground up in
acetone. Any bright light would cause the mixture to turn red. The best
results were when we used uv light which seemed to cause a red glow. I tell
my ninth and tenth graders that certain wavelengths of light excite some of
chlorophyll's electrons. In a chloroplast the energy of these electrons can
be used to make food, but if chlorophyll is just by itself the electrons go
back to their original state and as they go back they emit red light.
Any advice?
I'd like a better explanation, perhaps a better method. Why is the
suspension glowing red under uv light? Also I always notice some glowing
red leaves this time of year. Leaves do have red pigments but these
pigments don't normally glow red. Also I believe that senescence attacks
the enzymes of the light independent reaction and other proteins before it
gets to the relatively puny chlorophyll molecules. Perhaps chlorophyll is
really glowing red in the fall?
David Lauter
George Washington High
SF CA
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