Assume that in fruit flies the genes ABCD and E are very closelylinked in that order. A homozygous wild-type fly is irradiated withX-rays and then crossed to an aa bb cc dd ee tester strain. Amongthe progeny you find a fly that is phenotypically recessive forgenes b c and d. What type of lesion would best explain theseresults? ( I use lesion to refer to any kind of mutation: a pointmutation, or an aberration). What would you do to confirm yourhypothesis?
Assume that in fruit flies the genes ABCD and E are very closelylinked in that order. A homozygous wild-type fly is irradiated withX-rays and then crossed to an aa bb cc dd ee tester strain. Amongthe progeny you find a fly that is phenotypically recessive forgenes b c and d. What type of lesion would best explain theseresults? ( I use lesion to refer to any kind of mutation: a pointmutation, or an aberration). What would you do to confirm yourhypothesis?
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Two different antigen molecules that occur on the surface ofblood cells of wild-type mice are produced through thisbiosynthetic pathway.
Mice that are homozygous for null mutations in the gene thatencodes enzyme A (genotype aa) don't make either antigen 1or antigen 2. Mice that are homozygous for null mutations in thegene that encodes enzyme B (genotype bb) don't makeantigen 1. Mice that are homozygous for null mutations in the genethat encodes enzyme C (genotype cc) don't make antigen 2.All three genes are unlinked.
Two different true-breeding strains of mice have been isolatedthat donât make either antigen 1 or antigen 2. When an individualfrom one strain is crossed with an individual from the otherstrain, all of the F1 mice produce both antigens.
What are the complete genotypes of the two parental strains?Select two.
| AABBCC | |
| AAbbCC | |
| AABBcc | |
| AAbbcc | |
| aaBBCC | |
| aaBBcc | |
| aabbCC | |
| aabbcc PartB Two of the F1 mice are crossed to one another. What proportionof the F2 progeny will produce both antigen 1 and antigen 2? PartC If F1 mice are crossed to one another, what proportion of the F2progeny would be expected to produce antigen 1, but not antigen2? PartD If F1 mice are crossed to one another, what proportion of the F2progeny would be expected to produce antigen 2, but not antigen1? PartE If F1 mice are crossed to one another, what proportion of the F2progeny would be expected to produce neither antigen 1 nor antigen2? PartF Among the F2 progeny, there will be mice of several differentgenotypes that are phenotypically antigen 1â and antigen2â. If you wanted to use a testcross in order to testwhether any individual F2 mouse that doesnât produce either antigenis defective in the production of enzyme A, what would be the bestgenotype for the tester mouse? |
