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30 Cards in this Set
- Front
- Back
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Energy sources?
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organo- (organic chemicals)
litho- (inorganic chemicals) photo- (light) |
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Carbon sources?
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hetero- (organic compounds)
auto- (CO2) |
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chemoheterotroph/ chemoorganotroph
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energy source: organic chemicals
carbon source: organic |
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lithotrophic/
heterotroph/ mixotroph |
energy source: inorganic chemicals
carbon source: organic |
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photoheterotroph
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energy source: light
carbon source: organic |
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chemolithotroph/
chemoautotroph |
energy source: light
carbon source: CO2 |
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Prokaryotic traits
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1. fast metabolism
2. abundant 3. diverse |
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Methanogens
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e- donor: H2
e- acceptor: CO2 |
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Life requirements?
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self-reproducing
metabolism complex, ordered evolution by natural selection contains information (genes, DNA) catalysis |
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When did the big bang occur?
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14 billion years ago
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When did the Earth form?
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4.6 billion years ago
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What is the first evidence of life?
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C isotope fractionation - 3.8 billion years ago
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When was O2 in the atomsphere?
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2.9 byo
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When did first eukaryotes appear?
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1.4 byo
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when did plants and animals appear?
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0.8 byo
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Nature of first organisms
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lithotrophic
H2 oxidizing thermophilic deep, short branches on phylogenetic tree |
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Pyrodictium
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optimum temp: 105 degrees C
oxidizes H from minerals electron acceptor: So |
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Thermophily
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heat resistance due to:
1. lipid monolayers 2. positive supercoiling in DNA (holds strands together) 3. modified proteins (hydrophobic core, ionic aa) |
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Importance of Methanogens
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-degrades organic matter anaerobically
-natural gas -greenhouse gas |
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Why is it likely that Methanogenesis might have been primitive?
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1. substrate availability
2. methanogens are thermophiles 3. methanogenesis is "simple" 4. young sun |
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Methanogenesis
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4H2 + CO2 --> CH4 + 2H2O
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Acetogenesis
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4H2 + 2HCO3- + H+ ---> CH3COO- + 4H2O
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Methanogen habitats
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Geothermal
-hydrothermal vents -deep basalt aquafiers Anaerobic sediments -intertidal salt marsh -fresh water habitats -landfills -digestive tract |
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Ingredients to isolate methanogens?
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H2, CO2, minerals
anaerobic conditions |
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Catabolism
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energy generating
deltaG is negative dissimilation exergonic |
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Anabolism
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biosynthesis
deltaG is positive assimilation endergonic |
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Why are small subunit ribosomal RNA used to make phylogenetic trees?
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1. universal
2. conserved/ divergent 3. functionally same |
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How to make a tree?
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1. PCR
2. sequence each PCR product from each organism 3. align the sequences (can intro gaps to increase seq matches) 4. calculate evolutionary distances 5. make tree |
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Distance Matrix Analysis?
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examines # of differences in nucleotides in alignment
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Methanogenic Pathway
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CO2 --(H2)--> formic acid --(H2)--> formaldehyde --(H2)--> methanol --(H2)--> methane
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