In Drosophila, white (w), eosin(w^e), and wild-type red (w^+) are multiple alleles at a single l

step 1 Let's start by just making us some notes. Remember, this trait is a single locus on the X chromo

In Drosophila, white (w), eosin(w^e), and wild-type red...

In Drosophila, white $(w), \operatorname{eosin}\left(w^{e}\right),$ and wild-type red $\left(w^{+}\right)$ are multiple alleles at a single locus for eye color. This locus is on the $X$ chromosome. A female that has eosin (pale orange) eyes is crossed with a male that has wild-type eyes. All the female progeny are redeyed; half the male progeny have eosin eyes, and half have white eyes. Assume the female has two $x$ chromosomes and the male has one $X$ and one $Y$ a. What is the order of dominance of these alleles? b. What are the genotypes of the parents and progeny?

In Drosophila, white $(w), \operatorname{eosin}\left(w^{e}\right),$ and wild-type red $\left(w^{+}\right)$ are multiple alleles at a single locus for eye color. This locus is on the $X$ chromosome. A female that has eosin (pale orange) eyes is crossed with a male that has wild-type eyes. All the female progeny are redeyed; half the male progeny have eosin eyes, and half have white eyes. Assume the female has two $x$ chromosomes and the male has one $X$ and one $Y$
a. What is the order of dominance of these alleles?
b. What are the genotypes of the parents and progeny?

Key Concepts

Genotypic and Phenotypic Analysis of Crosses

This concept focuses on using knowledge of inheritance patterns to deduce the genotypes of parents and offspring from the observed phenotypes. It includes setting up Punnett squares, understanding the role of sex chromosomes in trait transmission, and comparing expected ratios to actual results in genetic crosses.

Allele Dominance and Hierarchy

Determining the order of dominance involves comparing phenotypes resulting from different allele combinations. In this context, establishing a dominance hierarchy means identifying which allele will mask the effect of another in heterozygotes, with the most dominant allele determining the phenotype when present.

X-linked Inheritance

This concept involves genes located on the X chromosome, where inheritance patterns differ between males (XY) and females (XX). For traits on the X chromosome, males have only one allele and are hemizygous, which directly expresses the phenotype, while females have two alleles that may interact via dominance or other genetic interactions.

Multiple Alleles at a Single Locus

When more than two alleles exist for a single gene in a population, it creates a series of potential genotypes. This concept is critical because it introduces complexity beyond simple dominant-recessive relationships and allows for a range of phenotypic expressions based on specific allele combinations.

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