Question

You are interested in mouse eye development and conduct a genetic screen for mutations that result in strong eye defects. After treating a male mouse with ENU (a chemical mutagen that induces base-pair changes and small deletions), you identify four mouse mutants 1-4, each with defective eyes.

You cross each of the four mutant mice with eye defects to homozygous wild type mice and examine the progeny from each cross. What type of information can you get from observing the progeny of each of these crosses?

a. how many different genes affect eye development amongst your mutants

b. Whether 2 different genes are mutated in the same mutant mouse.

c. Whether there exist 2 different mutations within the same gene in a particular mutant mouse.

d. Whether the mutations are dominant or recessive.

e. Both A and C

Next you cross the 4 mouse mutants with eye defects to each other and examine the progeny of these crosses. Collectively, what type of information can you get from observing these progeny?

a. How many different genes affect eye development amongst your mutants.

b. Whether 2 different genes are mutated in the same mutant mouse.

c. Whether 2 different mutations exist in the same gene in a particular mutant mouse.

d. whether the mutations are dominant or recessive

e. Both A and C

One of your original mouse mutants with defective eyes, (mutant 1) is very interesting. When you cross mutant 1 to homozygous wild type mice, all the mice in the F1 have normal eyes. When you cross the F1 mice to each other, you get a 9:7 ratio of normal eyes: defective eyes in the F2. Recalling your knowledge of Mendelian genetics from the beginning of the quarter, what is your interpretation of these F2 results?

a. original Mutant 1 is homozygous for dominant mutations in 2 different independently segregating genes. Mutations in either gene alone is sufficient to obtain the mutant eye defect phenotype.

b. original Mutant 1 is homozygous for dominant mutations in 2 different independently segregating genes. Mutations in both genes are required to obtain the mutant eye defect phenotype.

c. original Mutant 1 is homozygous for recessive mutations in 2 different independently segregating genes. Mutations in either gene alone is sufficient to obtain the mutant eye defect phenotype.

d. original Mutant 1 is homozygous for recessive mutations in 2 different independently segregating genes. Mutations in both genes are required to obtain the mutant eye defect phenotype.

Answer 1

c)whether there exist 2 different mutations within the same gene in a particular mutant house.

d)whether the mutants are dominant or recessive.

b)Original mutant 1 is homozygous for dominant mutations in 2 different independently segregating genes.Mutations in both genes are required to obtain the mutant eye defect phenotype.