Question

In drosophila, red eyes is the wild-type phenotype. Several different genes (with each gene existing in two or more alleles) are known to affect eye color. One allele causes purple eyes, and a different allele causes sepia eyes. Both of these alleles are recessive to red eye color. When flies with purple eyes were crossed to flies with sepia eyes, all the F_1 offspring had red eyes. When the F_1 offspring were allowed to mate with each other, the following data were obtained:

146 purple eyes
151 sepia eyes
50 purplish sepia eyes
444 red eyes
Explain the pattern of inheritance.

Answer 1

The pattern of inheritance in Drosophila eye color experiment follows Mendel's law of independent assortment, with red being dominant over purple and sepia. The cross resulted in a 9:3:3:1 phenotypic ratio in the F2 generation.

Step-by-step explanation:

The pattern of inheritance observed in the Drosophila eye color experiment describes a dihybrid cross with independent assortment of two autosomal genes. Each gene has a wild-type dominant allele and a mutant recessive allele. The red eye color is dominant over both purple and sepia eye colors. When purple-eyed flies were crossed with sepia-eyed flies, all their offspring (F1) showed the wild-type red eye color, indicating that the alleles for purple and sepia eye colors are recessive. The F2 generation, resulting from interbreeding of the F1 offspring, displayed a phenotypic ratio close to 9:3:3:1, with 444 red eyes (9 parts), 146 purple eyes (3 parts), 151 sepia eyes (3 parts), and 50 purplish sepia eyes (1 part). The ratio suggests that the two genes segregate independently according to Mendel's law of independent assortment.