MCAT® ExamBiological and Biochemical Foundations of Living SystemsEasy
A patient is diagnosed with a severe bacterial infection. A new antibiotic is prescribed that works by inhibiting the synthesis of bacterial cell walls. This antibiotic would most directly target and disrupt which of the following bacterial structures?
- ARibosomes
- BPlasma membrane
- CNucleoid
- DPeptidoglycan layer
Show answer & explanationAnswer & explanation
Correct answer: D. Peptidoglycan layer
Bacterial cell walls are primarily composed of peptidoglycan. An antibiotic that inhibits cell wall synthesis would specifically target the processes involved in building or maintaining this peptidoglycan layer, leading to the disruption of the cell wall and ultimately bacterial lysis.
Why the other options are wrong
- A. Ribosomes are involved in protein synthesis; while some antibiotics target them, this one targets cell wall synthesis.
- B. The plasma membrane is internal to the cell wall; while some antibiotics target it, this one specifically targets cell wall synthesis.
- C. The nucleoid contains the bacterial chromosome; antibiotics targeting this would disrupt DNA replication or transcription, not cell wall synthesis.
Bacterial Cell Wall
A rigid outer layer in bacteria, primarily composed of peptidoglycan, that provides structural support, maintains cell shape, and protects the cell from osmotic lysis.
- Composed mainly of peptidoglycan (murein).
- Provides structural integrity and protects against osmotic pressure.
- Gram-positive bacteria have a thick peptidoglycan layer.
- Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.
- Target for many antibiotics (e.g., penicillin).
Memory trick: Cell Wall's main ingredient is PEPTIDOGLYCAN, like bricks in a wall!