Final answer:
The antibiotic mechanisms for the listed substances include: penicillin and ampicillin inhibiting cell wall synthesis, Polymixin B injuring the cell membrane, sulfa drugs acting as competitive enzyme inhibitors, and Tetracycline, Streptomycin, Erythromycin, and Chloramphenicol interfering with protein synthesis at the 70s ribosome.
Step-by-step explanation:
Antibiotic Mechanisms and Corresponding Substances
The mechanism of action for various antibiotics can be categorized as follows:
Inhibit cell wall synthesis - Substances like penicillin and ampicillin block the biosynthesis of peptidoglycan, which is an essential component of bacterial cell walls. This action is bactericidal as it leads to osmotic lysis of the bacterial cells.
Injure the cell membrane - Polymixin B works by disrupting the structure of the cell membrane, leading to leakage of cellular contents and cell death.
Competitive inhibitors of enzymes - Drugs like sulfa act as competitive inhibitors of enzymes that are necessary for the synthesis of essential compounds in bacteria, thereby inhibiting bacterial growth.
Interference with protein synthesis at 70s ribosome - Antibiotics such as Tetracycline, Streptomycin, Erythromycin, and Chloramphenicol bind to the 30S subunit of the bacterial ribosome, blocking tRNA binding and peptidyl transfer during protein synthesis, which inhibits bacterial growth.
These antibiotics are selective towards bacteria due to the differences between prokaryotic and eukaryotic cell structures, exemplifying selective toxicity.