Multiple Choice
Which term describes the area located between the cell wall and the cell membrane in gram-positive bacteria?
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7. Prokaryotic Cell Structures & Functions
Introduction to Bacterial Cell Walls
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Which of the following substances does NOT protect a bacterium from phagocytosis?
A
Lipopolysaccharide (LPS)
B
Capsule
C
M protein
D
Peptidoglycan
Verified step by step guidance1
Understand the role of phagocytosis: Phagocytosis is a process where immune cells, like macrophages and neutrophils, engulf and destroy bacteria. Bacteria have evolved various mechanisms to avoid being phagocytosed.
Identify substances that protect bacteria from phagocytosis: Capsules, M proteins, and lipopolysaccharides (LPS) are known virulence factors that help bacteria evade phagocytosis. Capsules physically block recognition, M proteins interfere with immune recognition, and LPS can trigger immune responses that sometimes help bacteria avoid destruction.
Examine the role of peptidoglycan: Peptidoglycan is a structural component of the bacterial cell wall that provides rigidity and shape but does not directly protect bacteria from phagocytosis. It is not considered a virulence factor for evading immune cells.
Compare the options: Since capsules, M proteins, and LPS have protective roles against phagocytosis, and peptidoglycan does not, peptidoglycan is the substance that does NOT protect bacteria from phagocytosis.
Conclude that peptidoglycan's primary function is structural support rather than immune evasion, which is why it does not protect bacteria from phagocytosis.
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