In the figure, which diagram of a cell wall represents a structure that protects the bacterial cell against osmotic lysis?

• A. A cell wall lacking peptidoglycan and consisting only of proteins
• B. A cell wall composed primarily of phospholipids
• C. A cell wall containing a thick layer of peptidoglycan
• D. A cell wall made exclusively of lipopolysaccharides

Answer: (C)

Verified step by step guidance

1. Understand the concept of osmotic lysis: Osmotic lysis occurs when water moves into a bacterial cell due to a hypotonic environment, causing the cell to swell and potentially burst if it lacks a strong protective barrier.
2. Recall the composition of bacterial cell walls: Gram-positive bacteria have a thick layer of peptidoglycan, which provides rigidity and strength, while Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane containing lipopolysaccharides.
3. Analyze the role of peptidoglycan: Peptidoglycan is a polymer that forms a mesh-like layer outside the plasma membrane, giving structural support and preventing the cell from bursting under osmotic pressure.
4. Evaluate the options given: A cell wall lacking peptidoglycan or made only of proteins or phospholipids would not provide sufficient mechanical strength to resist osmotic pressure, whereas a thick peptidoglycan layer is specifically adapted to protect against osmotic lysis.
5. Conclude that the diagram representing a cell wall with a thick layer of peptidoglycan corresponds to the structure that protects the bacterial cell against osmotic lysis.