Mendel's Pea Plant Experiment: Understanding Alleles and Flower Colors
Mendel's Pea Plant Experiment
Mendel finds a new species of pea plant that produces two different flower colors, white and blue, based on a single gene with two alleles. He crosses together two parents, a true-breeding white and a true-breeding blue flowered plant. All of the plants in the F1 generation have blue flowers.
Inheritance of Flower Colors
The fact that all F1 offspring have blue flowers suggests that blue is the dominant allele (B) and white is the recessive allele (b). The parental generation is represented as BB (true-breeding blue) and bb (true-breeding white). When crossed, their offspring have a Bb genotype, expressing the blue phenotype.
F2 Generation
To determine the proportion of homozygous blue F2 offspring, we cross two F1 plants (Bb x Bb). Using a Punnett square, we can calculate the genotypes of the F2 generation:
- BB (25%): homozygous blue
- Bb (50%): heterozygous blue
- bb (25%): homozygous white