In Smurfs, dwarf (T) is dominant to tall (t), pink (B) is dominant to blue (b),
ID: 271184 • Letter: I
Question
In Smurfs, dwarf (T) is dominant to tall (t), pink (B) is dominant to blue (b), and happy (G) is dominant to gloomy (g). All loci are autosomal and not linked. The phenotypes of parents and their progeny are given for several crosses below. Determine the most likely genotypes for each parent and write them in the appropriate spaces below. Note that the parents may not be pure breeding.
Female Parent Phenotype Male Parent Phenotype Progeny Numbers and Phenotypes 84 Dwarf, Pink, Happy 86 Dwarf, Blue, Happy 26 Dwarf, Pink, Gloomy 27 Dwarf, Blue, Gloomy Dwarf, Pink, Happy Tall, Blue, Happy Please list the genotypes with no spaces. (ex: AA) Female Parent Genotype Height locus Color locus Disposition locus: Male Parent Genotype Height locus Color locus: Disposition locusExplanation / Answer
Height : All the offsprings are dwarf for height, which means the either the offsprings are homozygous (TT) or heterozygous (Tt) for dwarfness. Since, the female parent is dwarf and the male parent is tall and the offsprings are all dwarf, it means that both the parents must be homozygous for their respective genes, since for a "tall" phenotype, a homozygous allele combination is necessary since it is a recessive allele and for a "dwarf" phenotype, although both homozygous as well as heterozygous combination will work, heterzygous combination will also result in some offsprings being tall. Hence, both parents are homozygous for their respective genes.
Color : Offsprings are both blue and pink in color. Presence of Blue color in offsprings means that the recessive allele (b) must be present in the offsprings in homozygous manner (bb), which further means that both the parents have at least 1 recessive allele 'b' in their genotype. Since, the female parent is "Pink", and Pink is dominant to Blue, hence, it must have a heterozygous genotype of 'Bb' which shows a phenotype of Pink color. The male parent is Blue in color which we know is recessive trait, hence must be present in homozygous condition (bb).
Mood : Offsprings show both Happy and Gloomy mood while both Parents show Happy mood. For the offspring to show Gloomy mood, the recessive gene 'g' should be present in homozygous condition (gg) which means that both parents should have at least 1 recessive allele (g). Now, since both parents have Happy mood and we have already established the presence of at least 1 recessive allele, this means that the parents are heterozygous for the mood (Gg) with a phenotype of Happy mood.
Thus, the genotypes of Female and Male Parents can be depicted as follows :
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