Which type of bacteria contains teichoic acids?

• A. Gram-positive
• B. Gram-negative
• C. Gram-neutral
• D. Both Gram-positive and Gram-negative

Answer: (A)

Teichoic acids are characteristic components of Gram-positive bacterial cell walls. They come in two forms: wall teichoic acids, which are covalently linked to peptidoglycan, and lipoteichoic acids, which are anchored in the cytoplasmic membrane. Their presence contributes to the thick, teeming peptidoglycan layer and gives the cell surface a negative charge that helps with ion binding. Gram-negative bacteria, in contrast, have a thin peptidoglycan layer and an outer membrane, and they do not contain teichoic acids. This structural distinction makes Gram-positive organisms the ones that contain teichoic acids.