Please answer the following questions for me. 1. In Drosophila Black body (b) is
ID: 60971 • Letter: P
Question
Please answer the following questions for me.
1. In Drosophila Black body (b) is a mutant allele of the wild-type grey body (b+) and vestigial wings (vg) is a mutant allele of the wild-type normal wings (vg+).
Produce a Punnet square that would demonstrate the genotypic outcomes of the F2 generation from a parental cross of homozygous flies that were grey bodied with vestigial wings crossed with black body, normal wing flies.
Give the expected phenotypic ratio.
2.
When the above cross was actually conducted, the following outcome is seen.
283 grey body, normal wings
1,294 grey body, vestigial wings
1,418 black body, normal wings
241 black body, vestigial wings
Total 3,236 flies
Is this result consistent with the predicted outcome (Use Chi square)
Explanation / Answer
1. Cross between homozygous flies that were grey bodied with vestigial wings (b+b+ vgvg) and black body, normal wing flies (bb vg+vg+) will have the offspring with the following genotypes.
b+b+ vgvg* bb vg+vg+ = 100% bb+ vgvg+.-----------> F1 generation
Cross between F1 generation will have the offspring with the following genotypes. bb+ vgvg+* bb+ vgvg+ =
Assuming that wild type is dominant to mutant,
b+b+ vg+vg+ ------------------------> 1/16 (grey body normal wings)
b+b+ vg+vg ---------------------------> 2/16 (grey body normal wings)
b+b vg+vg+ ---------------------------> 2/16 (grey body normal wings)
b+b+ vgvg --------------------------------> 1/16 (grey body vestigial wings)
bb+vgvg+ ------------------------------> 4/16 (grey body normal wings)
bb+ vgvg --------------------------------> 2/16 (grey body vestigial wings)
bb vg+vg+ --------------------------> 1/16 (black body normal wings)
bbvgvg+ -----------------------> 2/16 (black body normal wings)
bbvgvg ---------------------------------> 1/16 (black body vestigial wings)
Thus, the phenotypic ratio of grey body normal wings: grey body vestigial wings: black body normal wings: black body vestigial wings = 9: 3: 3: 1