Question

Compare feedback inhibition with the mechanism of regulation based on the operon model.

Answer 1

Feature	Feedback Inhibition	Operon Model
Level of Control	Enzyme level: Controls the activity of enzymes that already exist.	Gene level: Controls whether or not enzymes are even produced.
Mechanism	The end-product binds to the allosteric site of an enzyme to change its shape.	The regulatory protein binds to the operator on DNA to block transcription.
Speed	Instantaneous: It can stop a metabolic pathway in milliseconds.	Slow: It takes time to stop transcription and wait for existing proteins to degrade.
Energy Conservation	Saves raw materials by stopping the chemical reaction.	Saves total energy by preventing the costly synthesis of mRNA and proteins.
Example	Isoleucine inhibits the first enzyme in its own synthesis pathway.	Tryptophan acts as a co-repressor to switch off the trp operon.