Outline how penicillin acts on bacteria and why antibiotics do not affect viruses

Sourav PanOctober 30, 2024

Answered

Here’s an outline explaining how penicillin acts on bacteria and why antibiotics do not affect viruses:

How Penicillin Acts on Bacteria

1. Mechanism of Action
   • Inhibition of Cell Wall Synthesis:
     • Penicillin interferes with the synthesis of peptidoglycan, a key component of bacterial cell walls.
     • It binds to and inhibits penicillin-binding proteins (PBPs) involved in the final stages of cell wall formation.
     • This leads to the weakening of the cell wall and ultimately causes cell lysis (bursting) due to osmotic pressure.
2. Effects on Bacteria
   • Bactericidal Effect:
     • The disruption of cell wall integrity results in the death of actively growing bacteria.
     • This is especially effective against Gram-positive bacteria, which have a thick peptidoglycan layer.
3. Types of Bacteria Affected
   • Gram-positive Bacteria:
     • More susceptible due to their thick peptidoglycan layer.
   • Certain Gram-negative Bacteria:
     • Some Gram-negative bacteria may be affected, especially those lacking effective outer membrane barriers.

Why Antibiotics Do Not Affect Viruses

1. Structural Differences
   • Lack of Cell Wall:
     • Viruses do not have cell walls; they consist of genetic material (DNA or RNA) surrounded by a protein coat (capsid).
   • No Metabolic Machinery:
     • Viruses lack the cellular machinery necessary for metabolism and reproduction; they rely on host cells for these processes.
2. Mechanisms of Infection
   • Intracellular Parasitism:
     • Viruses invade host cells and hijack the host’s machinery to replicate, making them inherently different from bacteria.
   • Targeting Host Cells:
     • Antibiotics target processes and structures specific to bacteria and do not affect the viral replication process.
3. Types of Viral Treatments
   • Antivirals:
     • Instead of antibiotics, viral infections are treated with antiviral medications that target specific stages of the viral life cycle (e.g., entry, replication, or release).

Summary

• Penicillin is effective against bacteria by disrupting their cell wall synthesis, leading to cell death.
• Antibiotics do not affect viruses because viruses lack the structures and metabolic processes that antibiotics target, requiring different treatment approaches.