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Problem: Red-green color blindnessis an X-linked recessive trait in humans. Polydactyly (extra fingers and toes) is an autosomal dominant trait. Martha has normal fingers and toes and normal color vision. Her mother is normal in all respects, but herfather is color blind and polydactylous. Bill is color blind and polydactylous.If Bill and Martha marry, what proportions of children with specific phenotypes would they be expected to produce? The answers only include the proportions of some of the possible phenotypes; other phenotypes are also expected to occur but are not included.A. 1/4 color-blind girls with normal fingers, 1/4 boys with normal vision and polydactylyB. 1/4 girls with normal vision and polydactyly, 1/8 boys with normal vision and polydactylyC. 1/8 color-blind girls with normal fingers, 1/4 boys with normal vision and polydactylyD. 1/8 color-blind girls with polydactly, 1/8 boys with normal vision and normal fingers

FREE Expert Solution

For this problem, we first determine the genotypes of Martha and Bill. 

Martha has normal color vision but is a recipient of an afflicted X chromosome from her father. That makes her a carrier, XbX+. But despite having a father with polydactyly, she has normal fingers, giving her an autosomal recessive allele, ff.

Bill  is color-blind (XbY) and polydactylous. It is a dominant allele but his mother has normal fingers. Thus Ff.

So basically this is a cross between XbX+ff and XbYFf.

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Problem Details

Red-green color blindnessis an X-linked recessive trait in humans. Polydactyly (extra fingers and toes) is an autosomal dominant trait. Martha has normal fingers and toes and normal color vision. Her mother is normal in all respects, but herfather is color blind and polydactylous. Bill is color blind and polydactylous.

If Bill and Martha marry, what proportions of children with specific phenotypes would they be expected to produce? The answers only include the proportions of some of the possible phenotypes; other phenotypes are also expected to occur but are not included.

A. 1/4 color-blind girls with normal fingers, 1/4 boys with normal vision and polydactyly

B. 1/4 girls with normal vision and polydactyly, 1/8 boys with normal vision and polydactyly

C. 1/8 color-blind girls with normal fingers, 1/4 boys with normal vision and polydactyly

D. 1/8 color-blind girls with polydactly, 1/8 boys with normal vision and normal fingers

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What scientific concept do you need to know in order to solve this problem?

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Based on our data, we think this problem is relevant for Professor Schul's class at MIZZOU.