Saran's Learn Microbiology

  CELL WALL OF ARCHAEA ·        The cell wall is present in most archaea except Thermoplasma and Ferroplasma . ·        The cell wall of Archaea is surrounding the cell outside the cytoplasmic membrane and is mediating the interaction with the environment. ·        Archaeal cell wall can be involved in Cell shape maintenance, Protection against Virus, Heat, Acidity or Alkalinity. ·        Archaea do not have Peptidoglycan but have Pseudomurein and different in its composition to Murein. ·    Archaea have Pseudopeptidoglycan and it is similar to bacterial peptidoglycan (morphologically, functionally) but is chemically distinct. ·        In Archaea, instead of NAM, it contains N-Acetyltalosamine Uronic Acid (NAT) linked to NAG, with peptide interbridges to increase strength. ·    In some Archaea, the Cell wall is composed of Glycan polymers like Glutaminylglycan, Heterosaccharide, Methanochondroitin or Pseudomurein, which can be further supported by an S-layer. ·       

Major Structural and Physiological characteristics of Bacteria and Archaea Characteristics Bacteria Archaea Cell wall Peptidoglycan Polymers other than Peptidoglycan Muramic acid in Cell wall Present Absent Membrane Lipids Composed of branched carbon chains attached to glycerol by ether linkage Composed of straight carbon chains attached to glycerol by ester linkage Chromosomes Single or few and Circular Single and Circular Number of Sequence shared with Eukarya One Three First Amino acid in Protein synthesis Methionine Formyl methionine rRNA Loop Lacking Present Common arm of tRNA Lacking Present Photosynthesis Present Absent Site of Photosynthesis Plasm