If a gene encoding a bacterial transpeptidase enzyme undergoes mutation, which of the following antimicrobials may no longer be effective against the mutated bacterium?
a. Macrolides
b. Polypeptide drugs
c. Tetracyclines
d. Penicillins
e. Quinolones

Verified step by step guidance

1. Identify the function of a transpeptidase enzyme in bacteria, which is crucial for cell wall synthesis by cross-linking peptidoglycan layers.
2. Understand that penicillins and other beta-lactam antibiotics target transpeptidase enzymes, inhibiting their function and thus preventing cell wall synthesis.
3. Consider the impact of a mutation in the gene encoding the transpeptidase enzyme, which may alter the enzyme's structure and reduce the binding affinity of beta-lactam antibiotics.
4. Evaluate the mechanism of action of each antimicrobial option: Macrolides inhibit protein synthesis, Polypeptide drugs disrupt cell membranes, Tetracyclines inhibit protein synthesis, Penicillins inhibit cell wall synthesis, and Quinolones inhibit DNA replication.
5. Determine that a mutation in the transpeptidase enzyme would most likely affect the efficacy of penicillins, as they directly target this enzyme.

Key Concepts

Transpeptidase Enzyme Function

Transpeptidase is an essential enzyme in bacterial cell wall synthesis, responsible for cross-linking peptidoglycan layers. This process provides structural integrity to the bacterial cell wall. Inhibiting this enzyme disrupts cell wall formation, leading to cell lysis and death, which is the mechanism of action for certain antibiotics, particularly beta-lactams like penicillins.

Antibiotic Mechanisms of Action

Different classes of antibiotics target specific bacterial functions. For instance, penicillins inhibit transpeptidase, while macrolides and tetracyclines primarily inhibit protein synthesis. Understanding these mechanisms is crucial for predicting the effectiveness of antibiotics against bacteria with mutated targets, as mutations can confer resistance to specific drugs.

Antibiotic Resistance

Antibiotic resistance occurs when bacteria evolve mechanisms to withstand the effects of drugs that once killed them or inhibited their growth. Mutations in genes encoding target proteins, such as transpeptidases, can lead to changes that prevent antibiotics from binding effectively, rendering them ineffective. This phenomenon is a significant concern in treating bacterial infections.