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Chapter

BIOL240 Chapter Notes -Great Salt Lake, Electrochemical Gradient, Halobacterium


Department
Biology
Course Code
BIOL240
Professor
Trevor Charles

Page:
of 2
MODULE 10
Part A: Overview of Archaea
Characteristics
- Inhabit extreme environments
- High temperatures
- Acidic pH
- Alkaline pH
- High salt concentrations
- Pathogenic examples do not seem to exist
Part B: The Extreme Halophiles
Overview
- Extreme halophiles: tolerate extremely high salt concentrations
- Chemoorganotrophs and obligate aerobes
- Halobacterium most extensively studied
- High [salt] stabilizes glycoprotein’s in cell wall
- Potassium ion solute to maintain water balance in cell
- High sodium outside cell, high potassium inside cell
- Use light to generate ATP using non-photosynthetic mechanism
- Rhodopisin instead of chlorophyll
Habitats
- Great Salt Lake
- Dead Sea high salt concentrations and high Mg ions
- Marine salterns
The Mechanism of Bacteriohodospin Activity
- Energy generating systems which are not photosynthetic
- Pigment retinal a type of carotenoid involved
- Retinal exist in trans and cis form
- Absorbs light at wavelength of 570
- Absorption of light causes trans cis
- High [proton] outside cell creating proton gradient
- Drive ATPase or proton pump
- Generation of ATP results
- Operate only under anaerobic conditions
Part C: Methanogens and Themoplasmatales
Methanogens
- Methanotrophs dependent on methane produced by methanogens’ metabolism
- Obligate anaerobes
- Found in range of anoxic habitats
- Convert substrates to methane to generate energy
- Methane strongest greenhouse molecule
Thermoplasmatales
- Thermophilic but not hyperthermophilic with opt. temp. around 55
- Acidophilic
- No cell walls and cytoplasmic membrane with unique structure
- Picrophilus grow below pH 0
- Tetraether lipoglycans stabilize cell membranes
Part D: Other Euryarchaeota
Thermococcales
- Hyperthermophiles which grow at above 100 degrees
- Thermococcus temp range of 70 95
- Pyrococcus has temp range of 70-106
- Obligate anaerobic chemoorganotrophs
- Elemental sulfur as terminal electron acceptor
- Motile tuft of glagella
Archaeoglobales
- Oxidize hydrogen or organic compounds
- Also use elemental sulfur
- Hyperthermophiles
- Irregular cocci shape
Part E: Crenarchaeota
Overview
- Most metabolize sulfur
- Hyperthermophiles
- Obligate anaerobes and either chemoorganotrophs or chemolithotrophs
The Korarchaeota
- distinguished phylogenetically
- have not yet been cultured in pure culture
Sulfolobus
- Best characterized of Crenarchaeota
- Name derived from sulfur metabolism and lobed shape
- Aerobic organism
- Thermoacidophiles create acidic pH through metabolism
- Opt. temp. of 70-80 C and pH of 2-3
- Autotrophic fix carbon dioxide
- Grows on sulfur crystals which they oxidize to sulphuric acid