Vol 66, No. 4 - International Technology and Engineering Educators ...

creativity towards understanding the interactions between
the bond strengths, the coiling of the DNA, and the different
base pair matchups of the DNA. Students will have to
utilize their creativity, critical thinking, problem solving,
and analytical skills when designing and constructing their
own DNA. It is recommended that students do this activity
individually.
Materials
Students should be encouraged to bring household items
for constructing their DNA. Necessary items are as follows:
wire-based materials that have the ability to bend and
fold easily (pipe cleaners, wire hangers, copper wire, etc),
glue, tape, Velcro, string, scissors—virtually anything that
has adhesive or sticky properties. The adhesive material
will serve as bonds. For constructing the base pairs,
students should use their creativity and pick materials that
are distinguishable in four different ways. For example,
construction paper of four different colors, or different types
of fabrics, rubber, and cardboard. Each student will need a
cylindrical rod, no smaller than 0.5 inches in diameter.
pairs with two bonds. As with any engineering sketch, it is
important to label each area and list what materials will be
needed for constructing their DNA.
The next step is the construction of the DNA. Using
Figure 1 as a guideline as to how DNA should look, students
should begin construction. First, create the backbone of the
DNA by using pipe cleaners or wire. Then students should
pick out what type of fabric, cardboard, or paper they want
to use to represent their base pairs. There are four base pairs
as mentioned earlier: ATGC. The fabric of choice should
be cut into four distinct shapes to represent each base pair.
Finally, an adhesive should be decided upon with which
to attach the base pairs; this will represent the bonds. For
instance, students may choose yarn to represent the bonds.
Using their sketches and materials, students should engineer
multiple DNA strands with different base pairings. It is
important to note that AT has two bonds and GC has three
bonds (i.e., AT will be attached by three pieces of yarn, and
GC will be attached by two pieces of yarn). Once the DNA
has been created, students should test each DNA.
To test the DNA, students first coil their DNA around a
cylindrical rod. Then students should hold the DNA—one
end in each hand—and slowly pull the DNA strands apart
from one another. While pulling the two DNA strands apart,
students should note their observations.
Procedure
Some sample household
items.
Teachers should begin the design challenge with an open
discussion with students by introducing DNA to the class.
Describe the basic characteristics of DNA. Teachers should
encourage students to question the properties of DNA
and the role it plays in our lives. Once the foundation of
DNA has been laid out, students should begin their design
challenge: to engineer their own DNA. The first step is to
sketch the types of DNA that they would like to engineer.
Students should focus on making three types of DNA, one
that is very strong, one that is very weak, and one that is a
mix of strong and weak. When designing the DNA, students
should keep in mind what properties would make the DNA
strong and weak. Students should be able to recognize
that base pairs with three bonds are stronger than base
Analysis and Redesign
Students should be encouraged to answer questions such
as: How long did it take to pull the DNA apart Was it hard
to pull the two strands apart If it was not hard, what could
be done to make it stronger How could they improve their
design to make it stronger or weaker Teachers should guide
students to think critically about their designs through these
types of questions.
Evaluation/Feedback
Students should present their DNA and observations to
the class. Teachers should end the activity by asking more
questions about what students have learned. This will
provide a nice wrap-up to the activity.
Lisa Goel, MS in Biomedical Engineering,
is currently working on the Technology
Operations and Business Innovation team at a
nano-medical diagnostic company, Nanobiosym,
Inc. She can be reached via email at lisagoel@
gmail.com.
• The Technology Teacher • December/January 2007