Multiple choice

Deletion of the leader sequence of trp operon of E.coli causes _________.

There is a leader sequence in gene controlling synthesis of tryptophan.

  1. increased transcription of trp operon

  2. decreased transcription of trp operon

  3. decreased transcription of trp operon in presence of tryptophan

  4. no effect on transcription

  5. transcription to occur constitutively
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A Correct answer
Explanation

Attenuator produces terminator loop in presence of high tryptophan and anti terminator loop in presence of low tryptophan. The attenuator sequence is present within the leader sequence of the operon. In absence of leader sequence, there will be no attenuation. So, no attenuator loop will be formed and transcription of operon will increase.

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