In the figure, which diagram of a bacterial cell wall is most resistant to many antibiotics such as penicillin?

• A. Archaeal cell wall
• B. Gram-negative cell wall
• C. Mycoplasma cell wall
• D. Gram-positive cell wall

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the structure of different bacterial cell walls. Gram-positive bacteria have a thick peptidoglycan layer, Gram-negative bacteria have a thin peptidoglycan layer plus an outer membrane, Mycoplasma lack a cell wall, and Archaea have unique cell wall compositions that differ from bacteria.
2. Step 2: Recognize that penicillin and many antibiotics target the synthesis of peptidoglycan, which is a major component of bacterial cell walls.
3. Step 3: Analyze why Gram-negative bacteria are more resistant: their outer membrane acts as a barrier to many antibiotics, preventing them from reaching the peptidoglycan layer effectively.
4. Step 4: Compare this to Gram-positive bacteria, which have a thick peptidoglycan layer but lack the outer membrane, making them generally more susceptible to antibiotics like penicillin.
5. Step 5: Conclude that the Gram-negative cell wall structure, with its protective outer membrane, provides greater resistance to many antibiotics such as penicillin.