Which component of the bacterial cell envelope determines cell shape and prevents the bacterium from bursting or collapsing in a hypotonic medium?
Answer and explanation
Correct answer: D. Peptidoglycan cell wall
- Step 1: The bacterial envelope typically consists of three layers: outer glycocalyx, middle cell wall, and inner plasma membrane.
- Step 2: The rigid cell wall is composed of peptidoglycan (murein), a cross-linked polymer of NAM and NAG residues.
- Step 3: This rigid framework provides mechanical tensile strength, resisting high internal osmotic turgor pressure and preventing osmotic lysis.
Answer
Peptidoglycan cell wall.
Why not the others: Glycocalyx capsule provides adherence and immune evasion but lacks mechanical rigid wall strength; Phospholipid plasma membrane is a selectively permeable osmotic barrier that bursts without a wall; Flagellar basal body is a motor complex anchoring bacterial flagella.
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