Multiple Choice
When a bacterial colony is present in water, what type of extracellular layer is typically produced by the bacteria?
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7. Prokaryotic Cell Structures & Functions
Introduction to Bacterial Cell Walls
Multiple Choice
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
Verified step by step guidance1
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.
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.
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.
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.
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.
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