This activity was created as an alternative to “A Chromosome Study” where students use a paper model of human chromosomes to cut and paste 23 pairs in order and diagnose a disorder like Down Syndrome. One of the problems with this activity is that cutting 46 chromosomes is time consuming and often students would lose pieces before they could tape them in order. I still think it is a good activity, because it helps students visualize how we count and pair chromosomes, and reinforces the concepts of diploid and haploid.
In this alternative version, I use Tasmanian Devil chromosomes as a model, mainly because they only have 14 chromosomes which means students won’t spend as much time cutting and pasting. The image shown of the chromosomes was loosely based on an image seen in Nature showing chromosomes of Tasmanian devils with facial tumor disease. The paper chromosomes used in the model were designed in Photoshop, but are not actual images of devil chromosomes.
Students cut out each chromosome and organize them in pairs based on their patterns and size, they number them to determine the diploid number for the species and then consider a situation where the animal has an extra chromosome. Students must determine which set has the extra chromosome and consider the concept of trisomy.
Grade Level: 9-12
Time Required: 35-45 minutes
You can also extend this lesson to include discussions about cancer and conservation. The species is now endangered due to a contagious form of cancer that causes facial tumors. This video can be used to introduce students to the organism they are studying:
HS-LS3-1 Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring.
HS-LS3-2 Make and defend a claim based on evidence that inheritable genetic variations may result from: (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and/or (3) mutations caused by environmental factors.