The trp repressor binds to the operator region of dna as a dimer (two repressor protein subunits bound together as a unit).you isolate a new mutant e. coli strain that you call rnovel. in this strain, the repressor protein cannot attach to dna (it cannot bind trpo+), but it can make dimers. in this strain, how is expression of the trp operon regulated? a. constitutiveb. induciblec. repressibled. noninducible

C. repressible

Explanation:

The trp operon in bacteria is a repressible operon. The regulatory gene codes for repressor protein. In the presence of tryptophan, the repressor (inactive) binds with tryptophan and gets activated. This active repressor attaches with operator and prevent polymerase to bind and thus inhibiting transcription of genes in the operon.

The mutant strain cannot attach to operator (trpO+) but it can make dimers. As the operator is mutated so it prevent binding of repressor to operator. Thus, expression of the trp operon is repressible.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".