Consider two mice that are heterozygous for insulin-like growth factor 2. From t
ID: 49477 • Letter: C
Question
Consider two mice that are heterozygous for insulin-like growth factor 2.
From the cross Igf2 Igf2m X Igf2 Igf2m ….
a. … what genotypic ratio would be expected?
b. … what phenotypic ratio would be expected?
Igf2 Igf2m X Igf2 Igf2m
Igf2 Igf2m X Igf2 Igf2m
Genotypic ratio:
Phenotypic ratio:
Explanation:
Igf2 Igf2m X Igf2 Igf2m
Genotypic ratio:
Phenotypic ratio:
Explanation:
Explanation / Answer
The gene coding for insulin growth factor is Igf2 and its mutant fom is Igf2m. The inheritance of mutant form results in dwarfism and this is not transcribed if inherited from the maternal side. The hiven cross is Igf2 Igf2m X Igf2 Igf2m and the genotype of the offpsring would be Igf2Igf2, Igf2Igf2m, Igf2mIgf2, Igf2mIgf2m.
Thus the genotypic ratio is 1:2:1 ratio of Igf2Igf2 (homozygous normal): Igf2Igf2m (heterozygous): Igf2mIgf2m (homozygous mutant).
The phenotypic ratio is, 1 :1 of normal : dwarf mice.
Explanation:
Half of the offspring inherit normal allele coding for insulin growth factor will be inherited from the paternal sode and they will be normal sized. Among the other 50%, the mutant gene is inherited from the father and they will be dwarf though the mother is normal.