Describing Prokaryotes handout. prokaryotic vs. eukaryotic cells.
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Transcript of Describing Prokaryotes handout. prokaryotic vs. eukaryotic cells.
Describing Prokaryotes
handout
prokaryotic vs. eukaryotic cells
Describing Prokaryotes
1. Phylogeny• Comparison of conserved genes (16S
rRNA)• Can group to species or sometimes sub-
species level• Does not always predict function or
metabolic capabilities (phylogeny ≠ function)
Describing Prokaryotes
1. Phylogeny
2. Physiology/Metabolism– Source of C– Source of energy– Electron acceptors
Electron Acceptors
• Internal and Organic =
• Oxygen =
• NO3-, Fe(III), SO4
2- , CO2 =
How organotrophs and lithotrophs make energy
Thermodynamics Oxidation/Reduction couples
•More Oxidized•More willing to take up electrons
•More reduced•More able to give up electrons
• Autotrophy – use CO2 as C – Phototrophy
• Oxygenic – produces O2 (electrons come from H2O)• Anoxygenic – no O2 production
– Electron donor» H2
» H2S, So
» Organic C» Fe2+
– Lithotrophy – use inorganic chemical as energy• Energy source
– H2
– HS-,So,S2O32-
– NH4, NO3-
– Fe2+
– Mn2+
• Heterotrophy – use organic C as C source• Fermentation• Aerobic respiration
– Electron Acceptor» O2
• Facultative– Electron acceptor
» Use O2 when available» Use fermentation or NO3
- when no O2
• Anaerobic respiration– Electron Acceptors
» NO3-, NO2-
» So, S2O32-, SO3
2-, SO42-
» Fe3+, Mn4+
» CO2
» Fumarate (organic C)
Describing Prokaryotes
1. Phylogeny
2. Physiology/Metabolism
3. Form & Structures• Cell wall - Gram positive, Gram negative,
Acid-fast• Endospores producing• Filamentous, motility, colony morphology…
Describing Prokaryotes
1. Phylogeny2. Physiology/Metabolism3. Form & Structures4. Habitat
• Temperature• pH• Pressure• Nutrient availability• Salinity
Describing Prokaryotes
1. Phylogeny
2. Physiology/Metabolism
3. Form & Structures
4. Habitat
5. Other functions/processes• N2 fixation
• Antibiotic production• pathogens
Examples
• Escherichia coli
• Methanococcus (lives in cattle gut, produce methane)
• Thiobacillus - example reaction
H2S +O2 SO42- + 2H+
• Geobacter metallireducens –acetate- + 8Fe3+ + 4H2O 2HCO3
- + 8Fe2+ + 9H+