Penicillin, an antibiotic inhibits bacterial growth. It is categorized as:

Explanation

Penicillin functions as a competitive inhibitor by mimicking the substrate that the bacterial enzyme would normally act upon, thus binding to the active site and blocking the actual substrate from binding. This inhibition is crucial for its antibacterial activity. Irreversible inhibitors, on the other hand, form permanent bonds with the enzyme, which is not the case with penicillin. Non-competitive inhibitors do not compete with the substrate for the active site, instead binding elsewhere on the enzyme to change its activity. While competitive inhibitors like penicillin can be reversible, the defining feature here is the competition for the active site.