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The Trp Operon quiz #3

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  • What happens to the trp operon when tryptophan levels are low in the cell?
    When tryptophan levels are low, the trp repressor remains inactive because there is no tryptophan to act as a corepressor. The inactive repressor cannot bind to the operator, so transcription of the trp operon proceeds, allowing the cell to synthesize tryptophan.
  • What type of operon is the trp operon, and what does this mean for its regulation?
    The trp operon is a repressible operon, meaning it is usually active but can be turned off (repressed) when tryptophan is present.
  • What is the primary function of the trp operon in bacterial cells?
    The trp operon encodes enzymes required for synthesizing tryptophan from scratch when it is not available in the environment.
  • How many genes are included in the trp operon, and what do they encode?
    The trp operon contains five genes, which encode enzymes necessary for the biosynthesis of tryptophan.
  • What role does the trp repressor protein play in the regulation of the trp operon?
    The trp repressor protein can bind to the operator to block transcription, but only when it is activated by binding to tryptophan.
  • What acts as the corepressor for the trp repressor protein, and what is the result of this interaction?
    Tryptophan acts as the corepressor; when it binds to the trp repressor, the repressor becomes active and can bind to the operator to inhibit transcription.
  • What happens to the trp operon when tryptophan levels are high in the cell?
    When tryptophan levels are high, tryptophan binds to the trp repressor, activating it, which then binds to the operator and represses transcription of the operon.
  • What happens to the trp operon when tryptophan levels are low in the cell?
    When tryptophan levels are low, the trp repressor remains inactive and cannot bind to the operator, so transcription of the trp operon proceeds, allowing the cell to synthesize tryptophan.
  • What type of operon is the trp operon, and what does this mean for its regulation?
    The trp operon is a repressible operon, meaning it is usually active but can be turned off (repressed) when tryptophan is present.
  • What is the function of the operator region in the trp operon?
    The operator is a DNA sequence where the trp repressor binds to regulate transcription of the operon’s genes.