Example: Mr. Spock + Jax
Punnett Squares can be used for ANY combination of genotypes that the parents have. For example, the mother might have one of each allele, the father might have only the vam37 allele. Or, one parent might have only the dominant allele, while the other has only the recessive allele. You can figure out the ratio of phenotypes for any two parents using a Punnett Square (or using Laws of Probability, for that matter, but that was last module).
So let's try one. Let's try mating Mr. Spock of Star Trek (you know by now I'm a dormant Trekkie) with Jax from one of those latter day Star Treks. Mr. Spock has a recessive pointy-ear allele, while Jax has one copy each of the round and pointy-ear alleles (the dominant and recessive alleles are called E and e, respectively).
This time we get (approximately) 2 round eared and 2 pointy eared kids, or 2:2 ratio.
photo credits: spock
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