Which of the following compounds is commonly found associated with the cell walls of Gram-positive bacteria, but not Gram-negative bacteria?

• A. Lipopolysaccharides
• B. Porins
• C. Outer membrane proteins
• D. Teichoic acids

Answer: (D)

Verified step by step guidance

1. Understand the structural differences between Gram-positive and Gram-negative bacteria, focusing on their cell wall composition.
2. Recall that Gram-positive bacteria have a thick peptidoglycan layer, whereas Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.
3. Identify that lipopolysaccharides (LPS), porins, and outer membrane proteins are components typically associated with the outer membrane of Gram-negative bacteria.
4. Recognize that teichoic acids are polymers of glycerol or ribitol phosphate and are embedded within the thick peptidoglycan layer of Gram-positive bacteria, playing roles in cell wall maintenance and ion regulation.
5. Conclude that teichoic acids are uniquely found in Gram-positive bacterial cell walls and not in Gram-negative bacteria, which lack this thick peptidoglycan layer and associated polymers.