Comparisons of Eubacteria, Archaea, and Eukaryotes

Characteristic Eubacteria Archaea

Eukaryotes

Cell wall gram +ve or gram -ve (structure) murein absent plasma membrane
Predominantly multicellularno no yes
Nucleus, membrane bound organelles no no yes
DNA circular circularlinear
Ribosome 70s 70s 80s
Membrane lipids ester-linked* yes no yes
Photosynthesis with chlorophyll yes no yes
Growth above 80o C yes yes no
Histone proteins present no yes yes
tRNA initiator fMet Met Met
Operons yes yes no
Introns in genome none some [a, 1, 2, 3, 4, 5, 6, 7, 8,] most
Capping and poly-A tailing of mRNA no no yes
Transcription factors required yes no yes
Methanogenesis no yes no
Nitrification yes no no
Denitrification yes yes no
Nitrogen Fixation yes yes no
Chemolithotrophy yes yes no
Gas vesicles present yes yes no
Sensitive to chloramphenicol, kanamycin and streptomycin yes no no
* Archaea membrane lipids are ether-linked
Adapted from here.
Property Eubacteria Archaea Eukarya
Cytological features
Nucleus No No Yes
Cytoskeleton No No Yes
Organelles (mitochondria, chloroplasts, Golgi apparatus, endoplasmic reticulum) No No Yes
Molecular features
DNA topology Negatively supercoiled Relaxed or positively supercoiled (in hyperthermophilic Archaea that contain reverse gyrase) Negatively supercoiled
Promoter structure Two conserved boxes at - 10 (TATAAT) and - 35 (TTGACA) from transcription start site TATA box and/or initiator element TATA box and/or initiator element
RNA polymerase One type; relatively simple subunit composition; binds directly to promoter (can be footprinted) One type; complex subunit structure (subunit pattern, genes, and serological properties similar to eukaryal RNA polymerase II); can be footprinted, but still requires basal transcription factors for promoter recognition [1, 2, 3,] Three types; complex subunit compositions; cannot be footprinted; require basal transcription factors for promoter recognition/binding
Basal transcription factors No TBP , TFIIB, and TIIS homologs of eucaryal RNA polymerase II-associated factors described thus far TBP, TAFs, TFIIA, TFIIB, TFIIE, TFIIF, TFIIH required for RNA polymerase II initiation; P-TEFb, TFIIS, TFIIF, elongin, and ELL required for elongation
Poly(A) tails in RNA Short Short (avg. 12 bases in length) Long
Chromatin No ? Yes

Table adapted from Archaeal chromatin: Virtual or real? Jordanka Zlatanova Proc. Natl. Acad. Sci. USA, Vol. 94, pp. 12251-12254, November 1997

For further features and references see the series of minireviews on Archaea published in the June 27, 1997, issue of Cell, and refs. 5 and 27.

 Cell walls of Prokaryotes  Electron acceptors for respiration and methanogenesis in prokaryotes  Glycolysis in bacteria  Lithotrophic prokaryotes  Gene Regulation in E.coli  Second Messengers  Cell signaling

1 Comments:

Blogger Big Dave Smith said...

These are a couple of pretty cool tables. The level of detail you have included is amazing.

Before I saw these tables, I did not know that DNA could be negatively supercoiled.

Keep it up!

3:37 PM  

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