So, I have run through the questions, but I just want to see if my answers were

Question

So, I have run through the questions, but I just want to see if my answers were correct. Thanks for the help. The questions are given, and the way to go about answering it are given as well.

"Given two vials of flies, one with all wild type characteristics and one with crimson eyes (crimson) and no wings (wingless), design a series of experiments to determine:

A. if crimson and/or wingless are dominant alleles.

Cross true breeding crimson wingless to wild type, check F1 phenotypes

B.   if crimson and/or wingless are sex-linked alleles.

Reciprocal cross true breeding crimson wingless to wild type, check F1 phenotypes

C. if crimson and wingless are linked genes or if they assort independently.

Take F1 and sibmate, check F2 for 9:3:3:1 ratio

Take F1 and testcross, check F2 for 1:1:1:1

     D. the map units between crimson and wingless, if crimson and wingless are linked.

      Take test cross data and use equation [nonparental/total] X 100"

Explanation / Answer

All your answers are correct!

A. if crimson and/or wingless are dominant alleles.

ANSWER-

1) Perform a Dihybrid Cross of True breeding Crimson eyes and wingless with True breeding wildtype characteristics.

2)Check F1 progeny phenotypic ratio. For a dihybrid cross the phenotypic ratio is 16:0 (dominant: recessive)

3)The Traits which show up in F1 phenotype are the dominant ones, the hidden traits are recessive.

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B.   If crimson and/or wingless are sex-linked alleles.

ANSWER-

1)Reciprocal cross true breeding crimson wingless male to wild type female, Check F1 phenotypes

2)Reciprocal cross true breeding crimson wingless female to wild type male, Check F1

If the gene is X linked dominant it will show up in both males and females.

If the gene is X linked recessive It will show up in both males and females. But it will show only in homozygous recessive condition in females (As females have two XX chromosomes).

If the gene is Y linked, It will show up only in males, It will always express and all males will be affected.

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C. If crimson and wingless are linked genes or if they assort independently.

ANSWER)

1) Perform a Dihybrid Cross of True breeding Crimson eyes and wingless with True breeding wildtype characteristics.

2)Perform self-cross of F1 progeny, Look for 9:3:3:1 ratio in F2 generation. Both the traits will assort independently being a combination of (ratio of white eye to crimson eye=3:1) (ratio of wings to wingless=3:1)

3)Perform test-cross of F1 progeny with Mutant recessive phenotype (true breeding homozygous).

3) If genes are independent F2 phenotype ratio will be 1:1:1:1, all type of gamete combinations will be produced.

4) If genes are linked we will see more of the parental phenotypes and less of the recombinant phenotypes .( Recombinant being Crimson eyes and Wild type wings, White eyes and wingless)

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D. The map units between crimson and wingless, if crimson and wingless are linked.

ANSWER) 1) Perform a Dihybrid Cross of True breeding Crimson eyes and wingless with True breeding wildtype characteristics.

2) Perform test-cross of F1 progeny with Mutant recessive phenotype (true breeding homozygous).

3) If genes are linked we will see more of the parental phenotypes and less of the recombinant phenotypes .( Recombinant being Crimson eyes and Wild type wings, White eyes and wingless)

Map Distance = (Number of recombinant offspring/ Total number of offspring ) x 100

Unit of genetic linkage is centiMorgan (cM)

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