Which of the following descriptions regarding tryptophan operon in E.coli is correct:()
A. it contains regulations in both transcription level and translation level
B. It contains regulations in both initiation step of transcription as well as termination step of transcription.
C. It contains both positive regulation and negative regulation.
D. It contains regulations for enzyme induction as well as enzyme repression.
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Besides the negative regulation of repressor protein, what’s the unique regulation of tryptophan operon:()
A. Repression
B. Induction
C. Attenuation
D. Catabolite repression
E. Anti-termination
Which of the following conditions lead to the highest expression of tryptophan operon:()
A. High concentration of Trp while low concentration of other amino acids.
B. High concentration of other amino acids while low concentration of Trp.
C. Both Trp and other amino acids are high concentration.
D. Both Trp and other amino acids are low concentration.
Tryptophan operon belongs to:()
A. negative regulation-induction system
B. negative regulation-repression system
C. positive regulation-induction system
D. positive regulation-repression system
An operon containing three structural genes can be regulated by negative transcriptional regulation, then which of the following statements is true:()
A. The operon contains three binding sites for repressor proteins.
B. The operon contains three promotors.
C. The inhibitor of the regulator protein of the operon would inhibit the transcription of structural genes.
D. The regulator gene of the operon can be located downstream of this operon.
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