How to Use a Punnett Square: Step by Step

Welcome to understanding Punnett squares and genetic inheritance!A Punnett square is a powerful tool that helps us predict how genetic traits are passed from parents to offspring.In genetics, we use letters to represent different forms of genes, called alleles. Capital letters represent dominant traits, while lowercase letters show recessive traits.For example, in pea plants, T represents the tall trait, which is dominant, while t represents the short trait, which is recessive.Each parent contributes one allele to their offspring. The combination of these alleles determines the offspring's genetic makeup.When these alleles combine, they create the offspring's genotype, which determines its physical characteristics.To set up our Punnett square, we'll start with two heterozygous parents, both with genotype Tt.First, we'll draw our two-by-two grid that will form our Punnett square.Next, we'll place Parent 1's alleles, T and t, across the top of the grid.And Parent 2's alleles, also T and t, down the left side.Now, let's fill in each box by combining the alleles. We'll work from left to right, top to bottom.For each box, we write the allele from the top first, followed by the allele from the side.For example, in the first box, we combine the capital T from the top with the capital T from the side to get TT.With our Punnett square filled in, we're ready to analyze the results.