In Drosophila mutations in the genes Dumpy wings Dw sepia ey

In Drosophila, mutations in the genes Dumpy wings (Dw), sepia eyes (se), and shaven bristles (sv) leads to abnormal dumpy wings, sepia colored eyes, and abnormally bristled flies, respectively. A cross between true breeding wild type flies and true breeding flies that display the dumpy wing, sepia eyes, and shaven bristle phenotypes results in an F1 that have abnormal wings. What are the expected genotypes if we cross F1 flies? What are the expected phenotypes ratios?

Your peers decide to do the same exact F1 cross. Of a total of 1,000 flies, they obtain 377 dumpy wing flies and, 142 dumpy wing and shaven bristle flies. Based on the expected phenotype ratios you obtained above, perform a chi-square test to make sure your expected ratios are in accordance with the observed values.

Solution

Let

A- allele for normal dumpy wings

B - allele for normal sepia eyes

C- allele for normal shaven bristles

a - allele for abnormal dumpy wings

b- allele for abnormal sepia wings

c- allele for abnormal shaven bristles

Phenotypes ratio: 27 : 9 : 9 : 9 : 3 : 3 : 3 : 1

27 for ABC that is normal dumpy wings, sepia eyes and shaven bristles

9 ABc phenotype that is normal dumpy wings and sepia eyes and abnormal shaven bristles

9 AbC phenotype that is normal dumpy wings and shaven bristles and abnormal sepia eyes

9 aBC phenotype that is abnormal dumpy wings, normal sepia eyes and shaven bristles

3 Abc phenotype that is normal dumpy wings, abnormal sepia eyes and shaven bristles

3 aBc phenotype that is normal sepia eyes and abnormal dumpy wings and shaven bristles

3 abC phenotype that is abnormal dumpy wings and sepia eyes and normal shaven bristles

1 abc phenotype that is abnormal dumpy wings, sepia eyes and shaven bristles