Question

In hamsters, ALBINISM (lack of color pigmentation) is recessive to FULL COLOR. At my house, we have both true-breeding ALBINO hamsters and true-breeding FULLY COLORED hamsters. While I was away on vacation, my pet sitter allowed my 2 groups of hamsters to interact (and possibly breed). Now I have a litter of FULLY COLORED hamsters, but I do not know the genotype of these individuals. Answer the following based on the new litter (F1) of hamsters.

Name the procedure to determine the genotype of these FULLY COLORED F1 hamsters with the dominant phenotype.

Based on the procedure named in a), show the 2 possible Punnett Squares that can be created in this situation. And for each Punnett Square, provide the expected PHENOTYPIC ratio.

Answer 1

Given information,
Albinism is an autosomal recessive character
Albinism = Recessive trait = a
WT skin color = Dominant trait = A

Parental cross: AA X aa
F1 progeny: Aa
Genotypic ratio = 100% Aa
Phenotypic ratio = 100% WT

To determine the genotype of the F1 hamsters, we can perform TEST CROSS.
i. If the F1 progeny is heterozygous
Test cross: F1 X Recessive homozygous parents
Test cross: Aa X aa
Progeny: Aa Aa aa aa
Genotypic ratio = 1 (Aa) : 1 (aa)
Phenotypic ratio = 50% WT and 50% Albinos

ii. If the F1 progeny is homozygous for the dominant allele
Test cross: F1 X Recessive homozygous parents
Test cross: AA X aa
Progeny: Aa  
Genotypic ratio = 1 (Aa)  
Phenotypic ratio = 100% WT  

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