In whippets, wild-type dogs are skinny. A mutation in the myostatin gene causes
ID: 12419 • Letter: I
Question
In whippets, wild-type dogs are skinny. A mutation in the myostatin gene causes dogs to become more muscular. Dogs containing one copy of the mutant myostatin gene are medium-muscled; dogs in which both copies of the myostatin gene are mutant are highly-muscled. A dog breeder mates a wild-type skinny dog with a highly-muscled dog. He then self-crosses the resulting F1 progeny. What are the phenotypic ratio in the F2 progeny?This question is an example of incomplete dominance.
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Explanation / Answer
wild-type dogs are skinny---DD
highly-muscled dog.========dd
medium-muscled---Dd
wild-type dogs are skinny---DD x highly-muscled dog.========dd
medium-muscled---Dd--F1 OFFSPRING
Dd--F1 OFFSPRING X Dd--F1 OFFSPRING
GAMETES
D
d
D
DD skinny
Dd medium
d
Dd medium
Dd higly
Ratio -1:2:1
Genotypic Ratio -1:2:1
Phenotypic - Ratio -1:2:1
GAMETES
D
d
D
DD skinny
Dd medium
d
Dd medium
Dd higly