GENETICS AND EVOLUTION
MOLECULAR BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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RNA polymerase and the active repressor must be present.
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RNA polymerase cannot be present, and the repressor must be inactive.
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RNA polymerase must bind to the promoter, and the repressor must be inactive.
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A corepressor must be present.
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Detailed explanation-1: -D-RNA polymerase must bind to the promoter and the repressor must be inactive.
Detailed explanation-2: -For a repressible operon to be transcribed, which of the following must occur? RNA polymerase must bind to the promoter, and the repressor must be inactive.
Detailed explanation-3: -The trp Operon: A Repressible Operon When environmental tryptophan is low, the operon is turned on. This means that transcription is initiated, the genes are expressed, and tryptophan is synthesized. However, if tryptophan is present in the environment, the trp operon is turned off.
Detailed explanation-4: -Operons may be inducible or repressible It turns on only when the sugar lactose is present (and other, preferred sugars are absent). The inducer in this case is allolactose, a modified form of lactose.