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Medels-son Medels-son
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8 years ago
In rats, gene B produces black coat color if the genotype isB–, but black pigment is not produced if the genotype is bb.

At an independent locus, gene D produces yellow pigment if the genotype is D–, but no pigment is produced when the genotype is dd.

Production of both pigments results in brown coat color. If neither pigment is produced, coat color is cream.

A third independently assorting gene involved in determination of coat color in rats is the C gene. At this locus, the genotype C– permits expression of pigment from genes B and D. The cc genotype, however, prevents expression of coat color and results in albino rats.

Part A

Determine the genotypes of parents that produce the following progeny: 27/64 brown; 16/64 albino;9/64 yellow; 9/64 black; 3/64 cream.

Enter your answers separated by a comma. Express your answer using "_" where any allele is possible. For example, forBbD_CC enter BbD_CC.

Part B

Determine the genotypes of parents that produce the following progeny: 9/16 brown; 3/16 black; 4/16 albino.

Part C

Determine the genotypes of parents that produce the following progeny: 3/8 black; 3/8 cream; 2/8 albino

Part D

Determine the genotypes of parents that produce the following progeny: 3/4 brown; 1/4 yellow.
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wrote...
8 years ago
9 black means => Bbdd or BBdd

9 cream means => bbdd

This means both parents definitely have recessive genotype => dd

bbdd implies that both parents have at least one b.

So parental genotypes: Bbdd * Bbdd or Bbdd * bbdd

[Note: bbdd parental genotype is not possible because in their litter at least one dominant B is there.]

Hope this helps. Thank You.
Medels-son Author
wrote...
8 years ago
Thanks; it was very helpful!
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