Penicillin

Question 1

What does penicillin do?

Answer 1

inhibits bacterial growth and kills bacteria

Question 2

What is the structure of penicillin?

Answer 2

Has a bicyclic structure with a 4-member B-lactam ring (cyclic amide) essential for the antibacterial activity of penicillin (broken ring, by acid or bacterial enzymes, penicillin no longer active)

5- member ring

Question 3

How was penicillin modified to become more acid resistant to acid hydrolysis?

Answer 3

initial form, Penicillin G

side chain was modified to become more acid resistant (Penicillin V), resistant to breakdown by the patient, or breakdown by the bacteria

Question 4

How does penicillin work?

Answer 4

antibiotics (penicillin) attacks cell well synthesis; humans do not have cell walls, little effect on humans but kills bacteria

beta-lactam antibiotics disrupts the formation of cell walls of bacteria but inhibits a key bacterial enzyme, transpeptidase

the high reactivity of the amide group in the ring causes it to irreversibly blind near the active site of transpeptidase as the ring breaks; inactivation of transpeptidase blocks the process of cell wall construction, prevents polypeptide cross-links from forming between the mucopeptide chains (without these links, cell wall is unable to support the bacterium, burst and dies)

Question 5

How do strains (resistant to antibiotics) resist effects of penicillin?

Answer 5

strains produce penicillinase (a B-lactamase), which opens the B-lactam ring of the penicillin, making it inactive (Penicillin G can be inactivated by penicillinase)

Question 6

Why is overprescribing an anti-biotic bad?

Answer 6

increased exposure of bacteria to the antibacterial agents, increased the number of resistant bacteria