During the course of the infamous Drosophila experiment, two students noticed a female fly that behaved in a peculiar manner. She crawled very slowly and did not fly. Realizing that this fly, collected as a virgin female, was abnormal, they did not use her in their experiment, but decided to investigate the inheritance of this tired trait. They crossed the tired female with a wild-type male and were surprised to find that all the F1 flies, male and female, exhibited the tired trait. They allowed these flies to mate and observed that all the F2 flies were tired. They generated an F3 and F4 generation. All flies were tired. Satisfied that they had a true-breeding stock, they performed reciprocal crosses with wild type. Wild-type males by tired females yielded all tired flies in the F1 and succeeding generations. However, when tired males were crossed to wild-type females, the F1 progeny were all wild type. Succeeding generations were wild type.
A. What type of inheritance is exhibited by tired? Explain. Suggest a likely location in the cell for this mutation. Explain.
During their studies, an apparently wild-type fly, a male, appeared in one of their tired stocks. Since the fly carried several other markers, these two students concluded--after much argument--that this fly was not a contaminant. They crossed this revertant male with a tired female from the pure-breeding stock. The progeny were phenotypically 50% tired and 50% wild type. Males and females were represented equally between both phenotypes.
B. Was the mutation that produced the wild-type phenotype in the unusual male dominant or recessive? Explain. What is the most likely origin of this mutation? Explain.
During the course of the infamous Drosophila experiment, two students noticed a female fly that behaved in a peculiar manner. She crawled very slowly and did not fly. Realizing that this fly, collected as a virgin female, was abnormal, they did not use her in their experiment, but decided to investigate the inheritance of this tired trait. They crossed the tired female with a wild-type male and were surprised to find that all the F1 flies, male and female, exhibited the tired trait. They allowed these flies to mate and observed that all the F2 flies were tired. They generated an F3 and F4 generation. All flies were tired. Satisfied that they had a true-breeding stock, they performed reciprocal crosses with wild type. Wild-type males by tired females yielded all tired flies in the F1 and succeeding generations. However, when tired males were crossed to wild-type females, the F1 progeny were all wild type. Succeeding generations were wild type.
A. What type of inheritance is exhibited by tired? Explain. Suggest a likely location in the cell for this mutation. Explain.
During their studies, an apparently wild-type fly, a male, appeared in one of their tired stocks. Since the fly carried several other markers, these two students concluded--after much argument--that this fly was not a contaminant. They crossed this revertant male with a tired female from the pure-breeding stock. The progeny were phenotypically 50% tired and 50% wild type. Males and females were represented equally between both phenotypes.
B. Was the mutation that produced the wild-type phenotype in the unusual male dominant or recessive? Explain. What is the most likely origin of this mutation? Explain.
