• in labs and many other mammals, coat color depends on two genes • One gene determines the pigment color (with alleles B for black and b for brown) • The other gene (with alleles E for color and e for no color) determines whether the pigment will be deposited in the hair A yellow lab and a chocolate lab have many puppies together. All the puppies are black labs. What is the genotype of the brown lab? bbEe BbEe bbEE BbEE
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All the puppies are black labs, which means they must have at least one B allele for black color. So, the yellow lab must have a B allele, and the chocolate lab must also have a B allele. This eliminates the options bbEe and bbEE. Show more…
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In the Labrador retrievers coat color may be black, chocolate (brown), or golden. Coat color is the interaction of two genes. One for pigment where B = black and b = brown, and the second for deposition of the pigment onto the hairs controlled by gene E = deposition and e = no pigment deposition. Golden is the result when no pigment can be deposited on the hair. Based on the following data, Parents: Black Dog X Golden Dog Offspring: 2/4 Golden 1/4 Black, and 1/4 Chocolate puppies What is the genotype of the parent dogs?
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In Labrador retrievers, the black coat (B) is dominant to the brown coat (b). A second gene determines whether or not the color will be expressed. The dominant allele (E) results in regular expression of either black or brown pigment. However, if the lab is homozygous for the recessive allele (ee), then the coat is yellow regardless of the genotype of the black/brown gene. Suppose that we cross two black Labs that are heterozygous for both traits. What proportion of each phenotype is expected in the puppies? b) What proportion of each phenotype is expected in the puppies from a cross between two black Labs that are heterozygous for the black/brown gene and homozygous recessive for the epistatic gene?
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In Labrador retrievers, coat color is controlled by two loci, each with two alleles: B,b and E,e. When pure-breeding black labs with the genotype BBEE are crossed with pure-breeding yellow labs of genotype bbee, the resulting F1 offspring all have a black coat. When a test cross is done with the F1 using a double homozygous recessive individual, the following phenotypic ratios are typically seen: 1 Black: 1 Chocolate: 2 Yellow. a. List the alleles, genotypes, and phenotypes. Which genotype is epistatic? b. What phenotypic ratios would you then expect from a heterozygous cross (BbEe x BbEe)?
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