Which domain lacks peptidoglycan in its cell walls?

Which domain lacks peptidoglycan in its cell walls?

• A. Archaea
• B. Bacteria
• C. Eukarya
• D. Protista

Answer: (A)

Peptidoglycan forms the rigid mesh of bacterial cell walls, and that distinctive polymer is not found in the cell walls of Archaea. Archaea either use pseudopeptidoglycan (pseudomurein) or other materials like proteins and polysaccharides to build their walls. This difference from bacteria explains why antibiotics that inhibit peptidoglycan synthesis affect bacteria but not archaea. In contrast, Eukarya (including Protista) generally lack peptidoglycan in their cell walls—plants have cellulose, fungi have chitin, and many protists have no cell wall at all. So, the domain that lacks peptidoglycan is Archaea.

Peptidoglycan forms the rigid mesh of bacterial cell walls, and that distinctive polymer is not found in the cell walls of Archaea. Archaea either use pseudopeptidoglycan (pseudomurein) or other materials like proteins and polysaccharides to build their walls. This difference from bacteria explains why antibiotics that inhibit peptidoglycan synthesis affect bacteria but not archaea. In contrast, Eukarya (including Protista) generally lack peptidoglycan in their cell walls—plants have cellulose, fungi have chitin, and many protists have no cell wall at all. So, the domain that lacks peptidoglycan is Archaea.