Teaching Haryana (HPSC) Assistant Professor Mock Test 2025 Life Sciences Fundamental Processes Control of gene expression
A heterozygote of E. coli was produced with the following combination of mutations:
trpR+ trpO- trpE+ /trpR+ trpO+ trpE+
where R is the repressor, O is the operator and trpE encodes the first enzyme in the biosynthetic cascade for tryptophan. Assume all other enzymes required are wild type. Which one of the following is the most likely phenotype of this E. coli ?
1
Synthesizes tryptophan irrespective of tryptophan status in the medium
2
Synthesizes tryptophan only when tryptophan is absent
3
Synthesizes tryptophan only when tryptophan is present.
4
Cannot synthesize tryptophan under any condition
5
Question Not Attempted