Question

question 16
2 points
repressible operons require that ______ binds to the repressor protein before it can bind to the operator.
a a coenzyme
b a cofactor
c the reactant
d the substrate
e the product

Explanation:

Repressible operons are typically involved in anabolic pathways. The repressor protein of a repressible operon is inactive on its own. When the end product (of the pathway controlled by the operon) accumulates, it binds to the repressor, activating it. The activated repressor then binds to the operator, turning off the operon. This is feedback inhibition at the transcriptional level. Coenzymes, cofactors, reactants, and substrates are not the molecules that activate the repressor in repressible operons.

Answer:

E. the product