Archaebacteria vs Bacteria vs Eukarya
The Three Domain System of Classification by Carl Woese (1977) based on variations in 16S rRNA sequence, divided the entire living organism in the biosphere into three major groups called Domains namely Archaea Bacteria and Eukarya or Eukaryota.
In the earlier systems of classifications, Archaea were treated as a unique type of bacteria called Archaebacteria and they were included in the Kingdom Monera along with true bacteria and Cyanobacteria (blue green algae). Now we are certain that Archaea possess distinct difference from true bacteria in their cellular structures and metabolic activities, and also they have a unique and separate evolutionary ancestry.
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Archaea shows some characters similar to true bacteria where as some unique sets of characters they share between eukaryotes. Due to these peculiarities, the group Archaea is now recognized as a distinct domain of life.
The present post article describe what all are the similarities and difference between Archaea, Bacteria (eubacteria) and Eukarya (eukaryote) with a comparison table for easy understanding.
Similarities and Differences Between Bacteria, Archaebacteria and Eukaryotes: Comparison Table
Sl. No. Features Bacteria (Eubacteria) Archaea (Archaebacteria) Eukarya (Eukaryotes) 1 Cell size Usually 0.5 – 4 µ Usually 0.5 - 4µ Greater than 5 µ 2 Membrane-enclosed nucleus with nucleolus Absent Absent Present 3 Complex internal membrane bounded organelles Absent Absent Present 4 Cell wall If present, almost always have peptidoglycan containing muramic acid Variety of types, no muramic acid in the cell wall No muramic acid, cellulosic if present (in plants) 5 Membrane Lipid Have ester linked, straight chained fatty acids Have ether linked branched aliphatic chains Have ester linked, straight chained fatty acids 6 Gas vesicles Present Present Absent 7 Transfer RNA Thymine present in most tRNAs No thymine in T or TψC arm of tRNA Thymine present 8 Formylation of Methionine (first amino acid in protein synthesis) Methionine formylated Methionine not formylated Methionine not formylated 9 Polycistronic mRNA Present Present Absent 10 Introns in mRNA Absent Absent Present 11 Introns in tRNA Absent Present Present 12 Post transcriptional modifications of RNA (mRNA Splicing, capping, and poly A tailing) Absent Absent Present 13 Ribosome size 70S 70S 80S 14 Elongation factor 2 (EF2) Does not react with diphtheria toxin Reacts with diphtheria toxin Reacts with diphtheria toxin 15 Sensitivity to chloramphenicol and Kanamycin Sensitive Insensitive Insensitive 16 Sensitivity to anisomycin Insensitive Sensitive Sensitive 17 RNA polymerase enzyme types One type Several types Three types (RNA Pol I, II, III) 18 Structure of RNA Polymerase Simple, 4 subunits Complex, 8-12 subunits Complex, 12-14 subunits 19 Rifampicin sensitivity of RNA polymerase Sensitive Insensitive Insensitive 20 Chromosomes and Replication of genetic material Covalently closed circular DNA with unique replication system Covalently closed circular DNA with replication system more or less similar to eukaryotes Linear chromosomes with unique replication system different from bacteria 21 Histones Absent Present Present 22 Plasmids Present Present Absent 23 Polymerase II type promoters Absent Present Present 24 Similar ATPase No Yes Yes 25 Methanogenesis Absent Present Absent 26 Nitrogen fixation Present Present Absent 27 Chlorophyll based photosynthesis Present in some forms Absent Present in plants 28 Chemolithotrophy Present Present Absent 29 Multicellularity Absent Absent Usually Present 30 Growth at temperature above 80oC Some can grow Most of them can grow None of them can grow
Key questions:
What are the difference between Archaea (Archaebacteria) and Bacteria (Eubacteria)?
What are the difference between Archaea (Archaebacteria) and Eukarya (Eukaryotes)?
How Archaea is different from Bacteria?
How Archaea is similar to Eukaryotes?
How to compare Archaea with bacteria and eukaryotes?
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