Question

(1 point)

5. Inside a prokaryote, such as E. coli, an operon controls for the production of the amino acid
tryptophan. What occurs in the cell in order to turn off the production of tryptophan?
Tryptophan binds with the promoter to block the DNA polymerase.
The operon binds to the RNA polymerase and releases the repressor.
Tryptophan binds with the repressor, allowing it to attach to the operator site, blocking RNA polymerase
The RNA polymerase binds to the tryptophan, activating the repressor, blocking the promoter.

Answer 1

The correct answer is Tryptophan binds with the repressor allowing it to attach to the operator site,blocking the RNA polymerase.

Step-by-step explanation:

Tryptophan operon contain 3 regulatory genes and 5 structural genes.The structural genes encodes enzymes for tryptophan biosynthesis.

The expression of tryptophan operon is tightly regulated by the the cellular level of amino acid tryptophan.

When the tryptophan level is high at that time the tryptophan bind with the repressor protein encoded by regulatory tryp R gene and then the repressor tryptophan complex binds to the operator region thus preventing the RNA polymerase enzyme to exert its action.