Question

Which of these properties do not agree with trp operon attenuator?

(a) It brings about repression of trp operon

(b) It consists of one stem loop system

(c) It has two codons for tryptophan in sequence

(d) Ribosome stalls at the attenuator

I got this question in exam.

This question is from Operons : Trp topic in section Gene Expression : Transcription Prokaryotes of Cytogenetics

Answer 1

Correct option is (b) It consists of one stem loop system

The best I can explain: Attenuator does’t just contain one loop but it can form two in presence of tryptophan and an alternate one in absence of the same for B. subtilis and one terminator and another anti-terminator loops for E. Coli. The other facts about trp operon are absolutely correct.