What is the primary structural difference in the cell wall between Gram-positive and Gram-negative bacteria? (Hard)
Answer and explanation
Correct answer: D. Gram-positive bacteria have a thick peptidoglycan layer lacking an outer membrane
- Step 1: Gram staining differentiates bacteria based on cell wall composition. Step 2. Gram-positive bacteria have a thick (20-80 nm) peptidoglycan meshwork with teichoic acids; Gram-negative bacteria have a thin peptidoglycan layer covered by an outer membrane with lipopolysaccharides. Answer: Gram-positive bacteria have a thick peptidoglycan layer lacking an outer membrane. Why not the others: Gram-negative peptidoglycan is thin; LPS outer membrane is exclusive to Gram-negative; Gram-negative still contain a thin peptidoglycan layer.
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