BackIn fruit flies, yellow body (y) is recessive to gray body , and the trait of body color is inherited on the X chromosome. Vestigial wing (v) is recessive to full-sized wing (v⁺), and the trait has autosomal inheritance. A cross of a male with yellow body and full wings to a female with gray body and full wings is made. Based on an analysis of the progeny of the cross shown below, determine the genotypes of parental and progeny flies.
[Table below appears at this point containing crosses and results]
Phenotype Number of Number of
Males Females _
Yellow body, full wing 296 301
Yellow body, vestigial wing 101 98
Gray body, full wing 302 298
Gray body, vestigial wing 101 103 _
800 800
In a species of fish, a black spot on the dorsal fin is observed in males and females. A fish breeder carries out a pair of reciprocal crosses and observes the following results.
Cross I Parents: black-spot male x nonspotted female
Progeny: 22 black-spot male
24 black-spot females
25 nonspotted males
21 nonspotted females
Cross II Parents: nonspotted male x black-spot female
Progeny: 45 black-spot males
53 nonspotted females
Identify which sex is heterogametic. Give genotypes for the parents in each cross, and explain the progeny proportions in each cross.
In a species of fish, a black spot on the dorsal fin is observed in males and females. A fish breeder carries out a pair of reciprocal crosses and observes the following results.
Cross I Parents: black-spot male x nonspotted female
Progeny: 22 black-spot male
24 black-spot females
25 nonspotted males
21 nonspotted females
Cross II Parents: nonspotted male x black-spot female
Progeny: 45 black-spot males
53 nonspotted females
Why does this evidence support the hypothesis that a black spot is sex linked?
Lesch–Nyhan syndrome (OMIM 300322) is a rare X-linked recessive disorder that produces severe mental retardation, spastic cerebral palsy, and self-mutilation.
What is the probability that the first son of a man whose brother has Lesch–Nyhan syndrome will be affected?
Lesch–Nyhan syndrome (OMIM 300322) is a rare X-linked recessive disorder that produces severe mental retardation, spastic cerebral palsy, and self-mutilation.
If the first son of the woman described in (a) is affected, what is the probability that her second son is affected?
Lesch–Nyhan syndrome (OMIM 300322) is a rare X-linked recessive disorder that produces severe mental retardation, spastic cerebral palsy, and self-mutilation.
What is the probability that the first son of a woman whose brother has Lesch–Nyhan syndrome will be affected?
In Drosophila, the X-linked echinus eye phenotype disrupts formation of facets and is recessive to wild-type eye. Autosomal recessive traits vestigial wing and ebony body assort independently of one another. Examine the progeny from the three crosses shown below, and identify the genotype of parents in each cross. <image>