Explain how a mutation can lead to antibiotic resistance in bacteria, providing a specific example of a mutation that confers resistance.
Answer
Mutation introduces new alleles; e.g., point mutation in gyrA confers fluoroquinolone resistance in E. coli.
The correct answer is Mutation introduces new alleles; e.g., point mutation in gyrA confers fluoroquinolone resistance in E. coli. — Thus mutation provides the genetic variation upon which selection acts for antibiotic resistance.
Step-by-step solution
- Mutation creates a novel allele that can alter protein function or regulation.
- In bacteria, point mutations in target genes reduce drug binding without harming the cell.
- Example: A single base‑pair change in the gyrA gene changes a serine to a leucine at position 83.
- This alters the DNA gyrase target of fluoroquinolones, lowering drug affinity and conferring resistance.
- Thus mutation provides the genetic variation upon which selection acts for antibiotic resistance.
Common mistake: Confusing mutation with selection or resistance mechanism
Concept tested: Mutation as source of adaptive change
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