Which of the following occurs in the trp operon?

A. The operon is usually off.

B. The operon is usually on.

C. The active repressor binds to the operator to stop transcription.

D. The inducer binds to the repressor and causes the inactive repressor to release from the promoter.

E. Tryptophan is the corepressor.

F. It is found only in eukaryotes.

G. It is found only in prokaryotes.

Answer: Options BCG

The operon is usually open, the active repressor binds to the operator to stop transcription and it is found in prokaryotes.

Explanation:

Trp operon are group of genes that can encode biosynthetic enzymes to produce tryptophan. They are found in E. coli a prokaryotes and are usually open. Trp operon is turned on when tryptophan levels are low and turned off when they are high.

It is regulated such that when tryptophan gene is available in the environment, the genes for tryptophan synthesis are not expressed. The active reprossor binds the promoter to stop transcription. It is regulated by tryptophan repressors.