An attached-X female fly, XXY (see the 'Insights and Solutions' box), expresses the recessive X-linked white-eye mutation. It is crossed to a male fly that expresses the X-linked recessive miniature-wing mutation. Determine the outcome of this cross in terms of sex, eye color, and wing size of the offspring.

Key Concepts

X-Linked Inheritance

X-linked inheritance refers to the pattern of inheritance for genes located on the X chromosome. In this case, the white-eye mutation and miniature-wing mutation are both recessive traits linked to the X chromosome. Males have one X and one Y chromosome, while females have two X chromosomes, which affects how these traits are expressed in offspring.

Genotype and Phenotype

Genotype refers to the genetic makeup of an organism, while phenotype is the observable physical or biochemical characteristics. In the given scenario, the genotype of the attached-X female fly is XXY, which influences its phenotype, including eye color and wing size. Understanding the relationship between genotype and phenotype is crucial for predicting the traits of the offspring.

Punnett Square

A Punnett square is a diagram used to predict the genetic outcomes of a cross between two organisms. By organizing the possible gametes from each parent, it allows for the visualization of potential genotypes and phenotypes of the offspring. This tool is essential for determining the ratios of traits, such as sex, eye color, and wing size, in the offspring of the given cross.