Domain Prokarya/Archaea Kingdom Archaea

Discovery of Archaea Prior to 1977 they were considered bacteria 1977 Carl Woese and George Fox proposed a new domain/kingdom 1990 16S rRNA and 18S rRNA sequences justify separation 2003 genome sequence analysis justifies kingdom/domain status

Multicellular Animals Shifting Kingdoms Lumpers Plantae Monera Archaea Splitters 2 3 5 6 8 Bacteria Archaebacteria Archezoans Euglenoids Chrysophytes Green Algae Brown Algae Red algae Slime Molds True Fungi Bryophytes Tracheophytes Protozoans Myxozoans Multicellular Animals

How Many Kingdoms? Extant 8 5 3 2 Extinct 1 Long Time with Multicellular Animals Myxozoans Protozoans Tracheophytes Bryophytes True Fungi Slime Molds Red algae Brown Algae Green Algae Chrysophytes Euglenoids Archezoans Archaebacteria Bacteria 8 5 3 2 Extinct 1 Long Time with Prokaryotes only The prokaryotes are a? Grade! Original Cell

Archaea Ancient origin, but appreciated more recently Somewhat more advanced than Bacteria Extremophiles-90°C pH2 25M anaerobic -4°C Antarctica! Methanogens Halophytes Sulfur metabolism DNA binding proteins (but not histones) Unicellular, colonial, filamentous Bacillus, coccus, spirillum, plate-like, etc. Size: 0.1 to 15 µm diam. x 200 µm long

Archaea Cladogram Extant Genera Crenarchaeota Euarchaeota to Eukarya Haloferox Halococcus Methanococcus Methanobacterium Thermofilum Haloarcula Pleurophillus Pyrococcus Thermococcus Archaeoglobus Ferroglobus Pyrobaculum Thermoproteus Sulfolobus Desulfurococcus Thermoplasma Pyrodictium Thermo- coccales Thermoplasmales Thermoproteales Igneococcales Halobacteriales Methanogenales Archaeoglobales Sulfolo- hales S+org->H2S+CO2 Hydrothermal vents MethanogenR lactate->H2+CO2 Autotroph H2+SO4-2->H2S Halophilic Chemoheterotroph resp O2 Chemoautotroph Light->bacteriorhodopsin->ATP Methanogens-anaerobes CO2+H2->F420 fluorescent ->CH4 Ruminant gut flora Marshes, landfills Crenarchaeota Euarchaeota Thermophilic Acidophilic Autotrophic (CO2) Sulfur + H2 -> H2S + H+ -O2 Heterotrophic (CH2O) Sulfur+CH2O->CO2+H2S +O2 Heterotrophic (TCAR) Sulfur + O2 -> H2SO4 to Eukarya to Bacteria Original Cell

Prokaryotic Growth Cells are generally very small Cells may double in size but only before binary fission Growth mostly in terms of cell number or colony size, etc. Doubling time in cell numbers may be 20 minutes in ideal conditions Could quickly take over the earth if conditions could remain ideal Very competitive in ideal environments Ultimate survivors - 3.5 billion years!

Cell Structure: Boundary Thermoplasma cell membrane bilayer phosphoglycerohydrocarbon, etc. sulfo- or glyco-glycerohydrocarbon (ether link not ester link) transport proteins cytosol regulates input/output Gram Positive Methanobacterium Gram Negative Thermoproteus cell wall-glycan (no muramic acid) prevents bursting turgor pressure thin surface layer glycoprotein releases dye

Homeostasis - metabolism Facultative and Obligate Anaerobes and Aerobes Nutrition Mode Energy Source Carbon Source Photoautotroph Light CO2 Chemoautotroph Inorganic chem Photoheterotroph Organic chem Chemoheterotroph Chemoautotroph acetyl-CoA or reverse TCA to fix CO2 Photoautotroph Calvin Cycle (Methanococcus, Pyrococcus) Chemoheterotroph citric acid cycle, fermentation Sulfur transporters used to drive ATP synthesis

How do Archaea tolerate the heat? Proteins stabilized by more ionic bridges between amino acid r-groups and more-hydrophobic core amino acids Heat shock protein (chaperonins) refold denatured proteins…Pyrococcus 121°C for 1 hour! DNA depurination reduced by presence of 2,3-diphosphoglycerate. DNA supercoiling by reverse gyrase reduces denaturation Sac7d in Sulfobolus is a minor groove protein increases the melting temperature by 40°C Histone-like proteins help stabilize DNA as well Heat-resistant di-bi-phytanyl diether lipid membranes (monolayer) prevent delamination of membrane

Cell Membrane Structure Composed of diglycerides R group may be phosphate, sulfate, or sugar Long chain branched hydrocarbon (not fatty acid) Hydrocarbons may be C20 or C40 If C20, the membrane is a bilayer: O R If C40, the membrane is a monolayer O R In some species, the membrane is a mixture of both C20 and C40 diglycerides forming a mixed mono-/bi-layer