In the figure showing different bacterial cell wall structures labeled A, B, and C, which diagram represents a Gram-negative cell wall?

• A. C: No peptidoglycan layer, only plasma membrane
• B. A: Thin peptidoglycan layer with an outer membrane
• C. B: Thick peptidoglycan layer without an outer membrane

Answer: (B)

Verified step by step guidance

1. Recall the key structural differences between Gram-positive and Gram-negative bacterial cell walls. Gram-positive bacteria have a thick peptidoglycan layer and no outer membrane, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.
2. Examine the descriptions of the diagrams: Diagram A shows a thin peptidoglycan layer with an outer membrane, Diagram B shows a thick peptidoglycan layer without an outer membrane, and Diagram C shows no peptidoglycan layer, only a plasma membrane.
3. Match the characteristics of Gram-negative bacteria to the diagrams. Since Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane, identify which diagram fits this description.
4. Confirm that Diagram A corresponds to the Gram-negative cell wall structure because it has both a thin peptidoglycan layer and an outer membrane, which are hallmark features of Gram-negative bacteria.
5. Understand that Diagram B represents a Gram-positive cell wall due to its thick peptidoglycan layer and lack of an outer membrane, and Diagram C likely represents a cell without a typical bacterial cell wall, such as a Mycoplasma.