Which generalization correctly distinguishes inducible from repressible operons?
- A
Inducible operons exist only in eukaryotes; repressible operons only in prokaryotes.
- B
Inducible operons lack a repressor; repressible operons have an activator.
- Ccheck_circle
Inducible operons are normally OFF and turn ON in response to a small molecule; repressible operons are normally ON and turn OFF when a corepressor accumulates.
- D
Inducible operons cannot be regulated allosterically.
Explanation
The lac operon is an inducible system (default OFF; allolactose induces) typical of catabolic pathways. The trp operon is repressible (default ON; tryptophan represses), typical of biosynthetic pathways.