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 (1). Archaea, (2). Eubacteria (Bacteria) and (3). 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.
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|
|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|
|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|
|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|
|23||Polymerase II type promoters||Absent||Present||Present|
|27||Chlorophyll based photosynthesis||Present in some forms||Absent||Present in plants|
|30||Growth at temperature above 80oC||Some can grow||Most of them can grow||None of them can grow|
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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