Question

Expression of T7 promoter- lac operator hybrid requires ___________

(a) T7 RNA polymerase

(b) An inducer such as IPTG

(c) Both T7 RNA polymerase and inducer such as IPTG

(d) T7 DNA polymerase

I had been asked this question in class test.

The doubt is from Promoters in portion Use of Cloned DNA of Genetic Engineering

Answer 1

The correct answer is (c) Both T7 RNA polymerase and inducer such as IPTG

For explanation I would say: Expression of T7 promoter- lac operator hybrid requires both T7 RNA polymerase and inducer such as IPTG. If inducer is absent levels of expression are very low.