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Genetics

Study Pack

Set 7 Linkage Recombination And Eukaryotic Gene Mapping

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Question 1

(Multiple Choice)

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You are doing lab work with a new species of beetle. You have isolated lines that breed true for either blue shells and long antenna or green shells and short antenna. Crossing these lines yields F1 progeny with blue shells and long antenna. Crossing F1 progeny with beetles that have green shells and short antenna yields the following progeny:
Blue shell, long antenna82
Green shell, short antenna78
Blue shell, short antenna37
Green shell, long antenna43
Total240
-Assuming that the genes are linked, what is the map distance between them in m.u.?

A) 33.3 m.u.
B) 25.0 m.u.
C) 49.5 m.u.
D) 8.0 m.u.
E) The genes are assorting independently.

Answer

Question 2

(Multiple Choice)

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Genetic distances within a given linkage group: (Select all that apply.)

A) cannot exceed 100 m.u.
B) are dependent on crossover frequencies between paired, nonsister chromatids.
C) can be measured in centiMorgans or map units.
D) cannot be determined.
E) can only be determined by physical mapping techniques.

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Question 3

(Multiple Choice)

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Dr. Disney has been raising exotic fruit flies for decades. Recently, he discovered a strain of fruit flies that in the recessive condition have baby blue eyes that he designates as bb. He also has another strain of fruit flies that in the recessive condition have pink wings that are designated as pw. He is able to establish flies that are homozygous for both mutant traits. He mates these two strains with each other. Dr. Disney then takes phenotypically wild-type females from this cross and mates them with double recessive males. In the resulting testcross progeny, he observes 500 flies that are of the following makeup:
41with baby blue eyes and pink wings
207with baby blue eyes only
210with pink wings only
42with wild-type phenotype
-Assuming the wild-type alleles for these two genes are b+ and pw+, what is the correct testcross of the F1 flies?

A) b+ pw+/b pw × b pw/b pw
B) b+ pw+/b pw × b pw+/b+ pw
C) b+ pw/b pw+ × b pw/b pw
D) b+ pw/b pw+ × b+ pw+/b pw
E) b+ pw+/b pw × b+ pw/b pw+

Answer