It prevents the enzyme from actually forming the peptidoglycan cell wall found around the membranes of bacterial cells. Now recall from biology that peptaglycan cell walls basically give that bacterial cell the ability to resist a high osmotic pressure. And it's because of that peptaglycan cell wall that once the bacterial cells enter our body that they don't actually immediately lice. So once again, that peptiglycan cell wall that we're going to discuss in just a moment basically allows that cell to resist a high osmotic pressure. Now, what we want to focus on in this lecture is the structure of penicillin and the actual mechanism by which penicillin acts on that bacterial enzyme. So let's begin with the structure of penicillin.