Teichoic acids are a component of the cell walls of which type of bacteria?

• A. Gram-negative
• B. Gram-positive
• C. Archaea
• D. Fungi

Answer: (B)

Teichoic acids are characteristic components of the cell walls in Gram-positive bacteria. They are embedded in the thick peptidoglycan layer and can be anchored to the cytoplasmic membrane as lipoteichoic acids, contributing to wall charge and adhesion. Gram-negative bacteria lack this thick peptidoglycan matrix and outer membrane structure that doesn’t accommodate teichoic acids, so they don’t normally contain them. Archaea and fungi have different cell wall compositions—archaeal walls often use pseudomurein or proteins, and fungal walls are primarily chitin and glucans—so teichoic acids are not typical there. Thus, teichoic acids are a defining feature of Gram-positive bacterial cell walls.