Students taking a genetics exam were expected to answer the following question by converting data to a 'meaningful ratio' and then solving the problem. The instructor assumed that the final ratio would reflect two gene pairs, and most correct answers did. Here is the exam question: 'Flowers may be white, orange, or brown. When plants with white flowers are crossed with plants with brown flowers, all the F₁ flowers are white. For F₂ flowers, the following data were obtained: 48 white 12 orange 4 brown Convert the F₂ data to a meaningful ratio that allows you to explain the inheritance of color. Determine the number of genes involved and the genotypes that yield each phenotype.' A number of students failed to reduce the ratio for two gene pairs as described above and solved the problem using three gene pairs. When examined carefully, their solution was deemed a valid response by the instructor. Solve the problem using three gene pairs

Key Concepts

Mendelian Inheritance

Mendelian inheritance refers to the principles of heredity established by Gregor Mendel, which include the concepts of dominant and recessive traits. In this context, the inheritance of flower color is influenced by alleles, where the white flower trait is dominant over orange and brown. Understanding these principles is crucial for interpreting the ratios of phenotypes observed in the F₂ generation.

Phenotypic Ratios

Phenotypic ratios represent the relative frequencies of different phenotypes in the offspring resulting from a genetic cross. In the given problem, the F₂ generation produced a ratio of 48 white, 12 orange, and 4 brown flowers, which simplifies to a 12:3:1 ratio. This ratio indicates the interaction of multiple gene pairs and helps in understanding the inheritance patterns of the traits involved.

Gene Interaction

Gene interaction occurs when two or more genes influence a single trait, leading to a variety of phenotypes. In this case, the presence of three gene pairs suggests that the inheritance of flower color is more complex than simple dominance. Understanding how these genes interact can help explain the observed phenotypic ratios and the genotypes responsible for each flower color.