Punnett Squares in Action
Punnett squares are visual tools that predict the genetic outcomes of a cross between two organisms. Named after Reginald Punnett, they help us see all possible combinations of genes that might occur in offspring.
Looking at the pea plant example shown, we can track multiple traits at once. The parent plant (RrYy) carries genes for both round/wrinkled shape and yellow/green color. The letters represent different alleles (gene variants) - uppercase for dominant traits and lowercase for recessive traits.
When we map out all possible combinations in the Punnett square, we can predict the ratio of offspring with different characteristics. In this case, we'd expect approximately 9 round yellow peas, 3 round green peas, 3 wrinkled yellow peas, and 1 wrinkled green pea out of every 16 offspring.
Genetics Tip: Think of Punnett squares as a genetic "multiplication table" that helps you calculate all possible outcomes of a genetic cross!