You are interested in observing independent assortment in Drosophila melanogaste

Question

You are interested in observing independent assortment in Drosophila melanogaster. You have established a true-breeding mutant line with curved wings (c), which is controlled by a single gene on chromosome 2, and sepia eyes (se), which is controlled by a single gene on chromosome 3. You establish a parental cross between true-breeding males with curved wings and sepia eyes and true-breeding wild-type females You then mate the F1 males and females to generate the F2 offspring. Map out this cross below, including expected genotypes and phenotypes of males and females at all stages of the experiment Include the expected phenotypic ratio for the F2 generation.

Explanation / Answer

Answer:

Wild wings = c+ ; curved wings= c

Wild eyes = se+ ; sepia eyes=se

c+c+ se+se+ X cc sese----------------Parents

c+ se+ c se---------------Gametes

c+c se+se (wild wings & wild eyes)----F1 (males and females are equal)

c+c se+se X    c+c se+se

F2

Phenotypes= (both wild) : (wild wings & sepia eyes) : (curved wings & wild eyes) : (curved wings & wild eyes)

Phenotypic ratio: 9 : 3 : 3 : 1

Genotypes:

c+c+ se+se+ : c+c+ se+se : c+c+ sese : c+c se+se+ : c+c se+se : c+c sese : cc se+se+ : cc se+se : cc sese

Genotypic ratio: 1 : 2 : 1 : 2 : 4 : 2 : 1: 2 : 1

In F2 ration also, all females and males are equal percentage as the genes are present on the autosomes.

c+ se+ c+ se c se+ c se c+ se+ c+c+ se+se+ (both wild) c+c+ se+se (both wild) c+c se+se+ (both wild) c+c se+se (both wild) c+ se c+c+ se+se(both wild) c+c+ sese (wild wings & sepia eyes) c+c se+se (both wild) c+c sese  (wild wings & sepia eyes) c se+ c+c se+se+ (both wild) c+c se+se (both wild) cc se+se+ (curved wings & wild eyes) cc se+se (curved wings & wild eyes) c se c+c se+se (both wild) c+c sese  (wild wings & sepia eyes) cc se+se (curved wings & wild eyes) cc sese (curved wings &sepia eyes)

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