Suppose a scientist generates several Drosophila melanogaster mutants that each
ID: 98240 • Letter: S
Question
Suppose a scientist generates several Drosophila melanogaster mutants that each have a different loss-of- function mutation in the bicoid gene, which is required for early embryonic development. He or she isolates RNA from the oocytes of mothers that are phenotypically wild type, but homozygous for one of the bicoid mutations. Then the researcher analyzes the bicoid mRNA size by northern blotting with a DNA probe that is complementary to the bicoid mRNA. He or she also uses in situ hybridization with a probe complementary to bicoid mRNA to analyze the oocyte expression pattern of bicoid mRNA. Sample A is a wild type control and samples B, C, and D are from the three loss-of-function mutations. Using the ene expression patterns on the right and the corresponding northern blot results on the left, match each lane of e gel with the most likely type of mutation. A B C D Wild type (A) bicoid (B) partial deletion insertion promoter missense hicoid (C) hicoid (D) Continued Below...Explanation / Answer
Lane B has partial deletion mutation that leads to deletion of the sequence and that leads to shorter mrna.
Lane C has missense mutation that will make nonfunctional protein but doesn't affect the amount mrna.
Lane D has promoter mutation that prevents the expression of bicoid gene and thus no mrna can be observed in the blot.
The mutant flies must have had the mother with one normal allele(Dominant) and one mutant allele and father could have been homozygous for mutant allele or heterozygous. And the mutant fly got the one mutant allele from mother and one mutant allele from the father and since bicoid is maternal effect gene so even though the flies are homozygous for the mutant allele but since the mother had normal dominant allele the flies will have the maternal phenotype.
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