Final answer:
A noncompetitive inhibitor binds to an allosteric site on the enzyme, causing a conformational change that prevents the substrate from binding properly to the active site.
Step-by-step explanation:
A noncompetitive inhibitor does not bind to the active site of an enzyme. Instead, it attaches to an allosteric site, which is a location other than the active site. This binding causes a conformational change in the enzyme, altering the shape of the active site so that the substrate can no longer bind properly. As a result, the enzyme-substrate complex either does not form at its normal rate or does not yield products at the normal rate.