Sunday, December 4, 2016

Let's Unwind with Candy DNA!

I just covered DNA structure and replication.  I wanted to do something that would be hands-on, but at the same time be quick and easy for them to grasp (considering the fact that we are nearing the end of the semester).  I remember I came across a fun activity on the Internet years ago called, "Have Your DNA and Eat It Too", from the University of Utah.   The activity comes with resources and an activity that requires more than what I wanted; however, I modified the activity to fit it within a 90-minute block period.

The materials can be bought at your local grocery store: Twizzlers (or licorice), colored marshmallows, toothpicks, and tape (I used Post-It notes in conjunction with the tape).
The activity required that each student obtain 9 of each colored marshmallow and 12 toothpicks to create 1 DNA molecule (although, they didn't use all the marshmallows as directed).  Therefore, I had students pair up in order to help me save resources since I had to purchase the materials myself.
The activity is pretty straightforward as it provides students with instructions on how to construct their DNA molecule. Even though the activity mentions base pairing in the introduction, students do have to have an understanding of how it works in order to generate the complementary strand from the information given to them.
After the DNA molecule was constructed, students were able to twist the DNA model into the characteristic double helix shape; which they thought was "dope" as seen in the video below.
Students then labeled the phosphate, sugar, and 1 of each of the bases.  The activity calls for masking tape, however, I used Scotch tape and Post-It notes as a substitute.
Once all pairs were finished, I briefly spoke about DNA replication; at which point I had students model part of the process by using scissors to act as DNA helicase to unzip the DNA strands. 
In the future, I may actually have students construct the complementary strands from the leading and lagging parent strands.  However, the students were all able to do well on an exit slip and a quiz that I provided, so the activity worked out in the end. 

What are your thoughts concerning this particular activity? Have you tried it before? If so, leave a comment below and let me know how it worked. 

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