A geneticist from an alien planet that prohibits genetic research brought with him to Earth two pure-breeding lines of frogs. One line croaks by uttering 'rib-it rib-it' and has purple eyes. The other line croaks more softly by muttering 'knee-deep knee-deep' and has green eyes. With a newfound freedom of inquiry, the geneticist mated the two types of frogs, producing F₁ frogs that were all utterers and had blue eyes. A large F₂ generation then yielded the following ratios: 27/64 blue-eyed, 'rib-it' utterer 12/64 green-eyed, 'rib-it' utterer 9/64 blue-eyed, 'knee-deep' mutterer 9/64 purple-eyed, 'rib-it' utterer 4/64 green-eyed, 'knee-deep' mutterer 3/64 purple-eyed, 'knee-deep' mutterer Indicate the genotypes of the six F₂ phenotypes.

Key Concepts

Mendelian Genetics

Mendelian genetics is the study of how traits are inherited through generations based on the principles established by Gregor Mendel. It involves understanding dominant and recessive alleles, as well as the segregation and independent assortment of genes during gamete formation. This framework is essential for predicting the genotypes and phenotypes of offspring based on parental traits.

Phenotype and Genotype

The phenotype refers to the observable characteristics or traits of an organism, such as eye color or croaking sound, while the genotype is the genetic makeup that determines these traits. Understanding the relationship between genotype and phenotype is crucial for interpreting the results of genetic crosses and predicting the traits of future generations.

Punnett Squares and Ratios

Punnett squares are a tool used to predict the genetic outcomes of a cross between two organisms. By organizing the possible gametes from each parent, one can visualize the potential genotypes and phenotypes of the offspring. The ratios derived from these squares help in understanding the inheritance patterns and can be compared to observed ratios in experimental data to validate genetic hypotheses.