A new recessive mutation in chickens that causes feather loss fromthe wings is b

Question

A new recessive mutation in chickens that causes feather loss fromthe wings is being investigated. Describe the expectedprogeny phenotypes from a cross between a hen with featherlesswings and a true-breeding wild type rooster if:

a. The gene coding for feather loss is on the Zchromosome

b. The gene coding for feather loss is on the Wchromosome.

c. The gene coding for feather loss is on an autosome.


Remember that, in chickens, the homogametic and heterogametic sexesare the reverse of those in mammals: females are WZ and males areZZ.

Can anyone help please? Thanks.

Explanation / Answer

a. Let's call the recessive feather loss gene Zf and the dominantwildtype gene ZF The hen has the recessive phenotype so the hen's genotype isWZf Truebreeding basically means homozygous and since the rooster hasthe wildtype phenotype it's genotype is ZFZF So let's do a cross: ZF ZF W            W ZF    W ZF Zf ZF Zf    ZF Zf All the progeny have the same phenotype, wildtype normalfeathers b. Let's call the recessive feather loss gene Wf The hen has the recessive phenotype and the gene is on the Wchromosome. So the hen's genotype is WfZ The rooster has the wildtype phenotype and it's genotype is ZZ So let's do a cross: Z    Z Wf           Wf Z    Wf Z Z Z Z       Z Z Here all the male progeny will have the wildtype phenotype. All the females will have the featherless wings phenotype. c. Let's call the recessive feather loss gene f. The dominant wildtype gene is F The hen has the recessive phenotype so the hen's genotype is ff The rooster has the wildtype phenotype and is truebreeding so it'sgenotype is FF So let's do a cross:    F       F f           Ff         Ff f   Ff         Ff All the progeny have the wildtype phenotype.

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