Archaea Flashcards
Polymers in cell wall
- Pseudomurein: N-acetyl-talosaminuronic acid
- chondroitin sulphate (Gram-pos)
- glycoprotein or protein (Gram-neg)
Cell Membranes
ether-linked, branched isoprene derivatives
- polar lipids: phospholipids, Sulpholipids and glycolipids
- non-polar lipids: sqaulene derivatives
Genetics and Molecular Biology
- chromosome can be smaller than bacteria
- G+C content varies between 21% and 68%
Metabolism
glucose broken down by Embden-Meyerhof pathway
Gluconeogenesis
reversed Embden-Meyerhof in halophyles and
methanogenes
Pyruvate oxido-reductase
oxidize pyruvate to acetyl CoA
Tricarboxylic acid cycle
halophyles and extreme thermophiles
Phylum Thaumarcheota
- soil and watery environments
- mesophillic ammonia oxidizers
- NB in nitrogen cycle
Thermophiles and methanogenes
- glycogen as reserve
- autotrophs
- CO2 fixed by reductive acetyl CoA path
Phylum Crenarcheota
- thermophiles
- acidophiles
- sulfate: electron acceptor
- H2S: electron donor
- anaerobes
- geothermically heated water or hot soil containing sulfur
Pyrodictium
- thermophiles
- hydrothermal vents in seabed
- 84-100C
Sulpholobus
- Gram-negative
- aerobe
- 70-80C
- pH 2-3
- lithotrophic growth on sulphur granules
- oxygen is electron acceptor, ferric iron used also
- thermoacidophiles
Thermoproteus
- anaerobic
- 70-95C
- pH 2.5-6.5
- chemolithotrophic, then using H2 and S
- CO and CO2 as carbon source
Phylum Euryarcheota
- lower temperatures
- sulfur-dependent metabolisms
Methanogens
- anaerobes
- energy through conversion of CO2, H2, acetate TO methane or methane and CO2
- methanogenesis
Methanogenes Coenzymes
- tetrahydromethanopterin (H4MPT)
- methanofuran (MFR)
- coenzyme M
- coenzyme F420
- coenzyme F430
CO2-reducing methanogens
form CH4 from H2 and CO2
Aceticlastic methanogens
cleave acetate to form CH4 and CO2
Halobacteria
- aerobe, respiratory metabolism
- chemoheterotrophs
- motile or non-motile
- high salt environment: 3-4M NaCl
Halobacterium salinarium
- produce purple membrane with archaerhodopsin when O2 low
- halorhodopsin: light energy to transport chloride ions
- photoreceptors to control the flagella
Thermoplasms
thermoacidophiles with no cell walls
Thermoplasma
- hot and acidic environment
- 55-59C
- pH 1-2
- diglycerol-tetra-ethers, lipopolysaccharides, glycoproteins
- histone-like proteins
- low temp: coccus
- high temp: filamentous
Picrophilus
- S-layer on outside of membrane
- irregular cocci
- aerobe
- 47-60C
- pH 0-3.7
Extremely thermophilic S-metabolizers
- thermophillic cocci with cell walls
- only one order
Thermococcales
- anaerobe
- flagella
- 88-100C
Sulphate-reducing Euryarchaeota
- Archaeoglobales
- Gram-negative
- irregular coccus
- glycoprotein subunits
- 83C
- coenzymes F420 and Methanopterin
- hydrothermal vents in ocean bed
