Tryptophan operon belongs to:()
A. negative regulation-induction system
B. negative regulation-repression system
C. positive regulation-induction system
D. positive regulation-repression system
查看答案
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.
The role of glucose in catabolite repression is:()
A. Improving the activity of adenylate cyclase, to increase the concentration of intracellular cAMP.
B. Inhibiting the activity of adenylate cyclase, to decrease the concentration of intracellular cAMP.
C. Improving the activity of phosphodiesterase, to increase the concentration of intracellular cAMP.
D. Inhibiting the activity of phosphodiesterase, to decrease the concentration of intracellular cAMP.
Which of the following conditions lead to the lowest expression of lac operon:()
A. Both glucose and lactose exist
B. Only glucose exists
C. Neither glucose nor galactose exists
D. Only lactose exists
Bacteria is intended to consume glucose at first, and enzymes to metabolize other sugars would be produced after exhaustion of glucose. This phenomenon can be called:()
Attenuation
B. Repression
C. Induction
D. Coordinate regulation
E. Catabolite repression
微信支付 
支付宝支付