An operon comprises of regulatory DNA sequences such as activator and repressor binding sites near the promoter and controls the transcription of structural genes as a single mRNA. Lac operon is a classical example of gene regulation related to the primary utilization of carbon source for energy in the gut bacterium, Escherichia coli. The transcription of structural genes is governed by availability of different concentration of glucose and/or lactose in the medium. Which of the following statements related to the Lac operon is/are true.

• A

  Repressor binds to the RNA polymerase.
• B

  cAMP level will be low in the absence of glucose.
• Correct answer
  C

  Lac operon works on the principle of negative regulation.
• Correct answer
  D

  If glucose is absent and lactose is present, high levels of lac mRNA will be synthesized.

Hence, the correct answer is options: 'C', 'D'.