Which of the Following Would Most Likely Be Controlled by a Repressible

Question

Which of the following would most likely be controlled by a repressible gene?
A) Tryptophan synthesis
B) Lactose catabolism
C) Arabinose catabolism
D) Tryptophan synthesis and lactose catabolism
E) Lactose catabolism and arabinose catabolism

Accepted Answer

Repressible genes are usually involved in anabolic pathways (biosynthesis) and their transcription is inhibited when the end product is present in sufficient quantities. Tryptophan synthesis is an example of an anabolic pathway that can be repressed by the end product, tryptophan itself.