Questions 1-8 are related. The drosophila alleles for black body (instead of the

Question

Questions 1-8 are related. The drosophila alleles for black body (instead of the normal tan color, which is the wild type) and curved wings (instead of the wild-type straight wings) are both recessive and on chromosome 2. Gene “C” designates color, with alleles C representing the dominant tan allele and c representing the recessive black allele, while gene “W” designates the wing shape gene with W being the dominant straight allele and w the recessive curved allele. You need to discover how close together these two genes are on chromosome 2. You place one male from a pure breeding stock and one female from a pure breeding stock (these are the ‘parental’ or ‘generation zero’ (G0) flies) into vial 1. The offspring of this cross (cross 1) hatch in vial 1. These offspring (Generation 1, G1) are heterozygous for both genes.

1. What is (are) the genotype(s) of the offspring of cross 1 (the genotypes of the G1 flies)?

CcWw

2. To perform the mapping experiment, you select a single male with the genotype of the one best answer from the list below and place it into a vial you label ‘vial 2’ along with a female from the doubly heterozygous flies from vial 1; this is cross 2. Assuming you have access to any fly type you want, which fly genotype would be best to cross to the doubly heterozygous fly to learn how close the color and wing genes are to each other on the chromosome?

CcWw

3. You perform the cross from the above question and get 500 offspring in vial 2 (these are the G2 flies). Among these G2 flies, 65 have tan bodies and curved wings, 70 have black bodies and straight wings, 190 have black bodies and curved wings, and 175 have tan bodies and straight wings. What are the genotypes of offspring with parental phenotypes? Select all that apply.

ccww

4. What are the genotypes of the recombinant offspring? Select all that apply.

Explanation / Answer

1. genotypes for generation 1 is CcWw( tan body straight wings)

2.i would choose CcWw( tan body straight wings)

3.the genotypes of the offsprings with parental phenotype are;

CcWw,CcWW,CCWw,CCWW

4. the genotypes of the recombinant offspring are:

Ccww,CCww,ccWw,ccWW,ccww

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