Suppose you discovered a female Drosophila melanogaster fly that was clearly sma

Question

Suppose you discovered a female Drosophila melanogaster fly that was clearly smaller than usual and had already been fertilized by at least one of the wild type males in the bottle. You isolate the female and allow her to lay eggs. All of her first generation offspring are small like the mother. Using this offspring as a starting point, design a set of experiments to help determine the type of inheritance for the trait. Indicate what results would be expected in each generation for each of the following types of inheritance: (a) autosomal dominant inheritance of the small body phenotype, (b) X-linked dominant inheritance of the small body phenotype, and (c) mitochondrial inheritance of the small body phenotype.

Explanation / Answer

Assume the genotypes are S and s, then the cross will give us the below data .

A.) here 2 types of cross are performed cross with wild phenotype and a cross with heterozygous individual

a.)Offspring with genotype Ss is crossed with wild genotype

Ss × ss = Ss,Ss,Ss,ss ;

b.) offspring with genotype Ss with a heterozygous individual with Ss

Ss × Ss = SS, Ss,Ss,ss;

since this is an autosomal dominant inheritance of small body the possible Result for 2 crosses is :

B.) in X-linked dominant inheritance all females and males will be small.

c.)The mitochondrial inheritance is through the maternal line, so newly formed embryos receive all their mitochondria from the mother.suppose if the mother mitochondrial genome is affected then all the next generations will inherit the affected mitochondrial genome.since the mitochondrial inheritance does not involve in any recombinations there is no chance of reduction of affected offsprings. So the type of Inheritance in this is mitochondrial inheritance.

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