BIOL 214 Exam 3 2020/2021 Questions and Answers

BIOL 214 Exam 3 2020/2021 Questions and Answers 1. The lactose operon is likely to be transcribed at a maximum rate when A) there is more glucose in the cell than lactose. B) the cyclic AMP levels are low. C) there is glucose but no lactose in the cell. D) the cyclic AMP and lactose levels are both high within the cell. E) the cAMP level is high and the lactose level is low. 2. Transcription of the structural genes in an inducible operon A) occurs continuously in the cell. B) starts when the pathway's substrate is present. C) starts when the pathway's product is present. D) stops when the pathway's product is present. E) does not result in the production of enzymes. 3. How does active CAP induce expression of the genes of the lactose operon? A) It terminates production of repressor molecules. B) It degrades the substrate allolactose. C) It stimulates splicing of the encoded genes. D) It facilitates the binding of RNA polymerase to the promoter. E) It binds steroid hormones and controls translation. 4. For a repressible operon to be transcribed, which of the following must occur? A) A corepressor must be present. B) RNA polymerase and the active repressor must be present. C) RNA polymerase must bind to the promoter, and the repressor must be inactive. D) RNA polymerase cannot be present, and the repressor must be inactive. E) RNA polymerase must not occupy the promoter, and the repressor must be inactive. 5. Allolactose induces the synthesis of the enzyme lactase. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell? A) The repressor protein attaches to the regulator. B) Allolactose binds to the repressor protein. C) Allolactose binds to the regulator gene. D) The repressor protein and allolactose bind to RNA polymerase. E) RNA polymerase attaches to the regulator.