Two genes interact to produce various phenotypic ratios among F2 progeny of a dihybrid cross. Design a different pathway explaining each of the F2 ratios below, using hypothetical genes R and T and assuming that the dominant allele at each locus catalyzes a different reaction or performs an action leading to pigment production. The recessive allele at each locus is null (loss-of-function). Begin each pathway with a colorless precursor that produces a white or albino phenotype if it is unmodified. The ratios are for F2 progeny produced by crossing wild-type F1 organisms with the genotype RrTt.
- Its a multiple choice question, this section goes up to Part G, but the next question will not appear after finishing Part D.
Part D. 9/16 red : 7/16 white
Select one of these options:
* At least one copy of both dominant alleles is required for red pigment. The absence of either dominant allele results in white.
* One copy of any dominant allele results in red. The absence of either dominant allele results in white.
* The only way to produce red is to have at least one dominant allele at one specific locus and homozygous recessive alleles at the other locus. The second dominant allele functions as a suppressor; therefore, if both dominant alleles are present, it will suppress the expression of the first.
Two genes interact to produce various phenotypic ratios among F2 progeny of a dihybrid cross. Design a different pathway explaining each of the F2 ratios below, using hypothetical genes R and T and assuming that the dominant allele at each locus catalyzes a different reaction or performs an action leading to pigment production. The recessive allele at each locus is null (loss-of-function). Begin each pathway with a colorless precursor that produces a white or albino phenotype if it is unmodified. The ratios are for F2 progeny produced by crossing wild-type F1 organisms with the genotype RrTt.
- Its a multiple choice question, this section goes up to Part G, but the next question will not appear after finishing Part D.
Part D. 9/16 red : 7/16 white
Select one of these options:
* At least one copy of both dominant alleles is required for red pigment. The absence of either dominant allele results in white.
* One copy of any dominant allele results in red. The absence of either dominant allele results in white.
* The only way to produce red is to have at least one dominant allele at one specific locus and homozygous recessive alleles at the other locus. The second dominant allele functions as a suppressor; therefore, if both dominant alleles are present, it will suppress the expression of the first.
