All of the following are found in the cell walls of Gram-positive bacteria except __________.

• A. peptidoglycan
• B. teichoic acids
• C. lipoteichoic acids
• D. lipopolysaccharide

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the structure of Gram-positive bacterial cell walls. Gram-positive bacteria have a thick peptidoglycan layer which provides structural support and shape.
2. Step 2: Identify the components typically found in Gram-positive cell walls. These include peptidoglycan, teichoic acids, and lipoteichoic acids, which are embedded within or attached to the peptidoglycan layer.
3. Step 3: Recognize that lipopolysaccharide (LPS) is a major component of the outer membrane of Gram-negative bacteria, not Gram-positive bacteria.
4. Step 4: Compare the options given and note that peptidoglycan, teichoic acids, and lipoteichoic acids are all characteristic of Gram-positive bacteria, while lipopolysaccharide is absent in their cell walls.
5. Step 5: Conclude that the correct answer is lipopolysaccharide, as it is not found in the cell walls of Gram-positive bacteria.