What Are the Parental Genotypes of Fruitflies with Mixed Phenotypes?

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Discussion Overview

The discussion revolves around determining the parental genotypes of fruitflies based on the phenotypic ratios of their progeny. The context includes genetic principles related to independent assortment and the inheritance of traits, specifically focusing on the wild type, ebony body, and vestigial wings phenotypes.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant presents a genetic cross involving a wild type fruitfly and another with an unspecified phenotype, leading to specific progeny ratios.
  • Another participant suggests starting by writing down all possible genotype combinations to explore potential solutions.
  • A participant proposes breaking down the problem by first analyzing the ebony body phenotype and then the vestigial wing phenotype, questioning the ratios produced by different types of crosses.
  • A later reply confirms the ratios derived from the analysis, suggesting a test cross for the ebony body trait and a monohybrid cross for the vestigial wings, leading to a proposed combination of parental genotypes.

Areas of Agreement / Disagreement

The discussion shows a progression of ideas, with some participants agreeing on the approach to analyze the problem, while the exact parental genotypes remain a point of exploration without consensus on a definitive answer.

Contextual Notes

Participants do not fully resolve the assumptions regarding the genetic ratios or the implications of independent assortment, leaving some steps in the reasoning process unexplored.

TytoAlba95
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Homework Statement


A wild type fruitfly was crossed with another fruitfly whose phenotype was not recorded. They had progenies in the following ratios. 3/8 wild type, 3/8 ebony body, 1/8 vestigial wings and 1/8 ebony body and vestigial wing. If the genes are located on different chromosomes and ebony and vestigial wings are recessive characters find out the genotypes of the parents?

A. ee vgvg & e+e+ vg+vg
B. ee vg+vg & e+e vg+vg
C. e+e vgvg & e+e+ vg+vg
D. e+e vg+vg & e+e vg+vg

Ans: B2. The attempt at a solution

I'm stumped and need some hints to begin solving from some point.
 
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I admit I have not checked, but if you have no idea what to do writing all possible combinations down is typically the best starting point (some of them can be probably ignored immediately, others will produce different ratios).
 
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Since the ebony body and vestigial wing traits assort independently, you can break the problem down into first looking only at the ebony body phenotype and then examining the vestigial wing phenotype. What is the ratio of flies with wild type bodies vs ebony bodies? What type of cross would produce that ratio? What is the ratio of flies with wild type wings vs vestigial wings? What type of cross would produce that ratio?
 
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Sorry for the late response. Thank you so much!
I got it completely!

What is the ratio of flies with wild type bodies vs ebony bodies? 3:3 i.e. 1:1, a test cross, so e+e x ee.
What is the ratio of flies with wild type wings vs vestigial wings? 3:1 What type of cross would produce that ratio? Monohibrid second gen cross, vg+vg x vg+vg

Combining both the parental genotypes are: e+e vgvg+(wildtype) and ee vgvg+(ebony).
 

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