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Which of the following occurs as a result of an abundance of tryptophan in E. coli?

a) The 5 trp genes (TrpA - TrpE) are not transcribed.
b) Stalling of the ribosome at trp codons in the leader sequence
c) The 5 trp genes (TrpA - TrpE) are transcribed, but not translated.
d) The leader sequence is not transcribed.

Respuesta :

Answer:

A) The 5 trp genes (TrpA - TrpE) are not transcribed.

Explanation:

  • The regulation of trp operon is controlled by the concentration of tryptophan, such that presence of adequate tryptophan in the growth medium, triggers the turn off of the transcription process as tryptophan biosynthesis is not necessary. Therefore; The 5 trp genes (TrpA - TrpE) are not transcribed.
  • At low concentration of tryptophan, the transcription process is turned on to produce more tryptophan. Th us the 5 trp genes (TrpA - TrpE) will be transcribed.

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