will participate in an activity which will demonstrate visually
how DNA electrophoresis through an agarose gel works.
One 50-60 minute
(1) Set up the obstacle
course on a playing field, gym or in a large classroom prior to
(2) Write the following
analogy on the board:
(3) Explain the rules
of the activity: Students, in groups of one, three or fifteen,
gather at the starting line and hold on to each other in a line.
They are not to release each other at any time during the race.
They are to move as quickly as possible through the course and
the first group to the finish line gets the candy reward. The
teacher marks the stopping point of each group when the winning
group finishes. These stopping points represent gel bands.
(4) Perform the activity.
(5) Lead a class discussion
to develop the following points: DNA is negatively charged and
fragments travel through the agarose gel from the wells toward
the positive end of the gel, driven by electric current. The DNA
fragments must travel through the matrix of tangled, agarose molecules.
Larger fragments move more slowly through the matrix and so don't
move very far from the wells. Smaller fragments can easily "slither"
through the agarose molecules and quickly move toward the positive
end of the gel and are represented as bands farther from the wells.
Show the transparency of "A DNA Agarose Gel" to explain
the length of the fragments in each of the bands and the distances
|Science Education Connection
Department of Biochemistry
The University of Arizona
May 1, 1997