In this activity, you’ll take on the role of geneticist, using Punnett squares to determine inheritance patterns for your toys!
Note: It’s a great idea to do this activity after you’ve completed the ‘Feeding the Population’ storyline in Tyto Online. If you haven’t completed this storyline or you’d like a refresher course on dominance, recessiveness, genotypes, and phenotypes, read this quick run-down first.
What is a Punnett square? A Punnett square is a chart that shows all of the potential genetic outcomes that two parents can produce in their offspring. For instance, if one parent has brown eyes and one parent has blue eyes, what are the odds that their offspring will have brown or blue eyes? A Punnett square can tell you!
2. Identify 3 ways that the toys are similar, but not exactly the same. These will be your toys’ genes.
3. Now describe those “genes” for both toys. These descriptions will be your toys’ alleles.
4. Make a table for your toys’ genes and alleles. You can download a printable table with blank Punnett squares here.
We now have a chart that describes the toys’ phenotypes. What we need to do next is to translate these into a genetic code that we can use for our Punnett square.
5. Think of a genotype for each of your toys’ genes (Remember, a genotype is a two-letter code that tells you which gene is being tracked, which alleles make up the gene, and whether those alleles are dominant or recessive.) Since this is all pretend, we can make up which alleles are dominant and which are recessive. Here’s what I came up with for Zebra and Evelyn:
Remember, just because one toy has a dominant feature doesn’t mean that both of its alleles are dominant. It may have one dominant allele and one recessive allele, making it a carrier for the recessive trait. You can’t tell whether someone with a dominant feature is a carrier for the recessive version or not just by looking at them, however.
6. Now it’s time to make some Punnett squares! We’ll make one for each of the toys’ three genes. If you don’t know how to create a Punnett square or need a refresher, click here. These are my results for Evelyn and Zebra:
7. Using the Punnett squares you’ve made, choose your three favorite genotypes and draw a picture of what this version of offspring would look like. Here is my sketch of a baby with an Eeffgg genotype: