Difference between Eubacteria and Archaebacteria
Both
Eubacteria and Archaebacteria and are single celled
prokaryotic microorganisms without a true nucleus and membrane bound organelles.
Eubacteria |
Archaebacteria |
Eubacteria are called “true
bacteria”. Large group of bacteria with rigid cell
walls, flagella, single circular DNA distinct from archaea |
Archaea are called “ancient
bacteria”. It is considered to be an ancient form of
life that evolved separately from bacteria and blue-green algae distinct from
eubacteria |
Found almost everywhere on
Earth. Fresh water, salt water, swamps, human guts
etc. |
Mostly grows in extremely harsh environments therefore
called as extremophiles. Archaea that lives in high acidic environment
(acidophiles) high temperature (Thermophiles), high salinity (halophiles) and
methane producing methanogens). Now, known to live everywhere, in ocean floor
to the cow gut. |
Peptidoglycan Cell wall made up of N-acetylglucosamine (NAG) and N-acetylmuramic
acid cross-linked via short peptide bridges |
Cell wall composed of various
polysaccharides and glycoconjugates In some archaea Pseudomurein is present: Instead
of NAM, it contains N-acetylalosaminuronic acid (NAT) linked to NAG, with
peptide bridges |
Plasma membrane: Eubacteria have
D-glycerol Glycerol connected to branched chain by ester
linkage Side chains are unbranched and made up of
fatty acids |
Archaean's plasma membrane have L-glycerol Glycerol connected to branched chain by ether
linkage Side chains are branched and made up of
Isoprene units |
70S ribosome. Sensitive to antibiotics that inhibit
ribosomal function in bacteria. |
70S ribosome. But Archaeal ribosomes have a
different shape and different protein composition This provides them with resistance to
antibiotics that inhibit ribosomal function in Eubacteria. |
Single RNA polymerase made up 5 subunits |
Single RNA polymerase made up 11~13 subunits depending on the species. Similar to the eukaryotic RNA Polymerase II |
Antibiotic sensitivity: Sensitive
to antibiotics. Most eubacteria are sensitive to penicillin because the antibiotic inhibits synthesis of peptidoglycan |
Archaebacteria is insensitive to many
antibiotics acting against eubacteria as cell wall lacks peptidoglycan.
Susceptible to the protein synthesis inhibitor fusidic acid and imidazole
derivatives. |
Photosynthesis: Cyanobacteria are
photosynthetic eubacteria, with ability to evolve oxygen. Bacteriochlorophyll
is involved |
Oxygen–evolving photosynthesis is absent.
|
Bacteriochlorophyll is involved in Photosynthesis |
In Halobacteria, bacteriorhodopsin is involved in photosynthesis |
Methanogenesis absent in eubacteria |
Methanogens that produce methane from carbon
dioxide as a metabolic by-product. |
The initiator tRNA of protein
synthesis is formylated methionine tRNAfMet |
The initiator tRNA is tRNAMet; not formylated just like eukaryotes |
Capsule; an outer layer of polysaccharides that covers the cells of many eubacterial species. |
Capsule rare or absent. |
Hami and Cannulae absent
|
Hami and Cannulae present. Hamus is an archaeal cell surface appendage; a long helical tube with three nano hooks at the far end. Cannulae: hollow
tube-like structures appear to connect cells after division forming network
of cells |
Examples: Escherichia coli Streptococcus pyogenes Lactobacillus acidophilus Cyanobacterium |
Halobacterium salinarum Salinibacter ruber Methanococcus Jannaschii Aeropyrum pernix |
Perras, A. K., Wanner, G., Klingl, A.,
Mora, M., Auerbach, A. K., Heinz, V., ... & Moissl-Eichinger, C. (2014).
Grappling archaea: ultrastructural analyses of an uncultivated, cold-loving
archaeon, and its biofilm. Frontiers in microbiology, 5, 397
Moissl C, Rachel R,
Briegel A, Engelhardt H, Huber R. The unique structure of archaeal 'hami',
highly complex cell appendages with nano-grappling hooks. Mol Microbiol. 2005
Apr;56(2):361-70.
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