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Purpose:
The introduction of these
two concepts will require considerable explanation by the teacher
with the aid of well-constructed diagrams. PCR and DNA fingerprinting
have become familiar in everyday life with the use of these techniques
for criminal investigations. A basic understanding of them will
help students to understand what they are hearing in the popular
media as well as showing that these techniques can be used equally
well to answer ecological and evolutionary questions.
Time:
One 50-60 minute class period
Materials Preparation:
Student Objective(s):
Lesson Plan:
(1) Teacher discussion of the size
and complexity of higher organism genomes and the need to only
look at small pieces of the genome to compare differences.
(2) Review of the natural process
of DNA replication within the cell. List the basic steps on the
board. This list can be student generated. Pose the question,
"How could the natural process of DNA replication be modified
to copy a DNA molecule in a laboratory?" Students can brainstorm
a procedure, before the explanation, if you desire.
(3) Relate history of the development
of PCR with the discovery of the heat-resistant Taq polymerase.
Use overhead transparency to explain each of the three steps in
one cycle of PCR.
(4) Describe how "regular"
PCR is used to amplify only a specific, known region of the genome
using two "flanking" primers. Compare this process to
using one primer of "random" sequence to amplify many
regions of the genome without knowing exactly where the DNA has
amplified from.
(5) Assign the background reading
"Polymerase Chain Reaction and DNA Fingerprinting" and
the worksheet "Polymerase Chain Reaction: Amplification of
DNA."
Supporting Materials:
Other Resources:
| Science Education Connection
Department of Biochemistry The University of Arizona May 1, 1997 warder@u.arizona.edu
http://biology.arizona.edu/sciconn/lessons/alongi/ |