Table of Contents

• Punnett Squares in Theory
• 1: Introduction
• 2: The Punnett Menu
• 3: Creating combinations chez Punnett
• 4: Insults by the dozen
• 5: Punnett menu revisited
• Punnett Squares in Practice
• 6: Onwards to Genetics
• 7: Recap of genetics vocab
• 8: Can this marriage be saved?
• 9: Vampire Fangs
• 10: Example: Spock and Jax
• 11: Example: Spock and Nurse Chapel
• Bigger Punnett Squares
• 12: And you thought we were done!
• 13: The Dreaded Double Hybrid
• 14: Another Dihybrid Cross
• 15: Is the ratio exact? (Hint: NO!)
• 16: Review

Learning outcomes

After completing this module you should be able to:

• Explain the difference between an allele, a genotype and a phenotype
• Construct and use Punnett Squares for a single allele
• Construct and use Punnett Squares for a two allele pairs (a dihybrid cross)
• Use Punnett squares to determine the probability (ratio) of a particular genotype and phenotype in a given matching

Introduction

In this module, we're going to talk about an approach to probability which is specific to genetics, called Punnett Squares. Punnett Squares were invented by one Reginald Punnett, a British geneticist who also studied ribbon worms and played cricket with G. H. Hardy of Hardy-Weinberg fame, one of the true big cheeses in the genetics world.

In this module, you'll see how Punnett Squares are really just a graphical way of reproducing the basic rules of probability.

You'll also see how to predict the phenotypic outcome from a multi-loci genotypic cross – in other words, how to predict what the kids will look like.