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Archaea 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 Lumpers Shifting Kingdoms Plantae Monera Archaea Splitters 2 3 5 6 8 Bacteria Bacteria Bacteria Bacteria Bacteria Archaebacteria Archaebacteria Archaebacteria Archaebacteria Archaebacteria Archezoans Archezoans Archezoans Archezoans Archezoans Euglenoids Euglenoids Euglenoids Euglenoids Euglenoids Chrysophytes Chrysophytes Chrysophytes Chrysophytes Chrysophytes Green Algae Green Algae Green Algae Green Algae Green Algae Brown Algae Brown Algae Brown Algae Brown Algae Brown Algae Red algae Red algae Red algae Red algae Red algae Slime Molds Slime Molds Slime Molds Slime Molds Slime Molds True Fungi True Fungi True Fungi True Fungi True Fungi Bryophytes Bryophytes Bryophytes Bryophytes Bryophytes Tracheophytes Tracheophytes Tracheophytes Tracheophytes Tracheophytes Protozoans Protozoans Protozoans Protozoans Protozoans Myxozoans Myxozoans Myxozoans Myxozoans Myxozoans Multicellular Animals Multicellular Animals Multicellular Animals Multicellular Animals Multicellular Animals Extant How Many Kingdoms? 8 5 3 Extinct 2 1 The prokaryotes are a? Original Cell Grade! 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 ThermoThermoplasmales Thermoproteales Igneococcales coccales Halobacteriales SulfoloMethanogenales Archaeoglobales hales Halophilic Chemoheterotroph resp O2 Chemoautotroph Light->bacteriorhodopsin->ATP S+org->H2S+CO2 Hydrothermal vents MethanogenR lactate->H2+CO2 Autotroph H2+SO4-2->H2S Methanogens-anaerobes Euarchaeota CO2+H2->F420 fluorescent ->CH4 Ruminant gut flora Marshes, landfills to Bacteria Original Cell Crenarchaeota to Eukarya Thermophilic Acidophilic Autotrophic (CO2) Sulfur + H2 -> H2S + H+ -O2 Heterotrophic (CH2O) Sulfur+CH2O->CO2+H2S +O2 Heterotrophic (TCAR) Sulfur + O2 -> H2SO4 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 cytosol Gram Positive Methanobacterium cell membrane bilayer phosphoglycerohydrocarbon, etc. sulfo- or glyco-glycerohydrocarbon (ether link not ester link) transport proteins regulates input/output 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 CO2 Photoheterotroph Light Organic chem Chemoheterotroph Organic chem Organic chem 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 O O O R R If C40, the membrane is a monolayer O O O O R R In some species, the membrane is a mixture of both C20 and C40 diglycerides forming a mixed mono-/bi-layer