Mycobacteria have a large amount of a component in their cell wall that other bacteria lack. That component is which?

• A. Fatty acids
• B. Murein
• C. Sterols
• D. Teichoic acid

Answer: (A)

Mycobacteria stand out because their cell wall is extremely lipid-rich due to very long-chain fatty acids known as mycolic acids. This waxy layer makes the wall highly hydrophobic and gives the characteristic acid-fast staining properties, as well as resistance to many dyes and to desiccation. Among the options, fatty acids best capture this distinctive feature, since mycolic acids are a type of fatty acid that is unusually long and abundant in the mycobacterial envelope.

Murein (peptidoglycan) is a common bacterial component and not unique to mycobacteria; teichoic acids are typical of Gram-positive bacteria; and sterols are not a defining, abundant cell wall component in this group.