So bacterial cells use trans peptidase to basically build cell walls. And what penicillin does is it acts as a suicide inhibitor, that is, it binds into the active side of that enzyme, and it begins the catalyzation process. But somewhere down that line, it forms an intermediate that essentially blocks and inhibits the activity of that enzyme, the transpeptidase. Now, aspirin, which has the following structure, is a suicide inhibitor to an enzyme we call cycloxygenase. And what cycloxagenase normally does is it basically catalyzes the formation of a special type of signal molecule that is used in the inflammation process. And so when we actually ingest aspirin, aspirin acts as a suicide inhibitor, and it binds into the active side of that cycloxigenase.