Flashcards
Archaea
Flashcards do conjunto (30)
- 1Small Subunit rRNA (SSU rRNA)1. Defines phylogeny
2. RNA is ubiquitous
3. Sufficiently conserved to relate all life
4. Multiple variable regions, good for discrimination - 2M1. Align sequences do that homologous residues are juxtaposed
2. Count number of differences between pairs of sequences; that is some measure of "evolutionary distance" that separates organisms
3. Calculate 'tree', the relatedness map, that most accurately represents all pairwise differences - 3Woese's Method1. Grow cells in (32)PO4 because showed RNA and DNA
2. Collect pellets; isolate total RNA
3. Separate 16S rRNA using gel electrophoresis
4. RibonucleaseT1 RNAase (cleaves single-stranded RNA after guanine residues on their 3' end)
5. Results: Oglionucleotides were separated and sequenced by two-dimensional electrophoresis
6. Proved relatedness of all life - 4Archaea1. Discovered in 1977
2. Based on 16S rRNA sequence
3. size: 0.1 to over 15 micrometers (usually small, though)
4. Can form longer aggregates or filaments
5. Have variety of cell walls (S layers, pseudomurein) but not peptidoglycan
6. Various shapes: rod, spiral, lobed - 5Characteristics of the Archaea Domain1. Single circular chromosome
2. Can have plasmids
3. Currently >600 genomes finished or in production
4. Genome size range 0.5-5.5 Mbp
5. Reproduce asexually
6. Not known to produce spores
7. Most are uncultured but known because of 16S sequencing of environment with universal primers - 6Archaea Cell Membrane1. L-glycerol instead of D-glycerol
2. Side chains bound by ether
3. Side chains in phospholipid bilayer is isoprene - 7Archaea and Bacteria Similarities1. No nucleus
2. NO membrane-bound organelles
3. DNA in single loop
4. Genes grouped in operons
5. Metabolic genes similar
6. Size - 8Archaea and Eukaryotes Similarities1. Similar RNA polymerases
2. Methionine initiates protein synthesis
3. Histones (spools around which DNA winds)
Contrast:
1. Bacteria have simple RNA polymerase, control transcription initiation through sigma factors - 9Energy Conservation: Chemoorganotropy and Chemolithotrophy1. Bioenergetics and intermediary metabolism are similar to Bacteria
2. Exception is methanogensis
3. Glucose Metabolism (different from Eukarya, only in Bacteria and Archaea)
4. Oxidation of acetate to CO2 (variation of TCA)
5. Electron Transport Chain with cytochromes, establish proton motive force and ATP through ATPase in membrane
6. H2 common electron donor and energy source for chemolithotrophy - 10Autotrophy in Archaea1. Acetyl-CoA pathway in methanogens and most hyperthermophiles
2. Calvin Cycle in Methanococcus jannaschii and Pyrococcus spp (both hypperthermophiles) - 11Why study Archaea?Provide insight in
1. Biotecnology: Archeae survive extreme conditions, therefore give insight to limits of life
2. Archaea are fundamental components of iochemical cycles on Earth or dominate special ecosystems (i.e. methanogens)
3. Offers hindsight in early evolution - 12Ecology of Archaea1. Widespread
2. Estimated to be 20--40% of microbial biomass in some habitats (oceans, swamps)
3. Symbionts of insects and animals (digestive systems)
4. No pathogens identified up to date - 13Archaea grouped in three categories1. Methanogens
2. Halophiles
3. Extreme thermophiles - 14Methanogens1. Only in archaea
2. Polyphletic
3. Strict anaerobes - 15Major Reactions and Substrates for Methanogens1. CO2, H: C02+4H2 -> CH4 +2H2O
2. Acetic Acid: CH3COOH -> CH4+CO2
3. Methanol: 4CH3OH -> 3CH4+CO2+2H2O
4. Methylamine: 4CH3NH2+2H2O -> 3CH4+CO2+4NH3 - 16Volta Experiment1. Demonstrated methanogensis
2. By Alessandro Volta - 17Anaerobic Habitats for MethanogensGrow in
1. Anaerobic soil of wetlands (swamps)
2. Rice paddies
3. Landfills
4. Rumen and GI tract of some mammals
5. Marine benthic sediments - 18Hydrogen-Consuming MethanogensCO2+4H2->CH4+2H2O
1. Ecologically important in anaerobic environments because removes excess hydrogen produced by other species during fermentation
2. Methanogens get rid of H2 so bacteria can ferment
3. More methanogens, more acetate, less succinate
4. Bacteria will select for methanogens - 19Where are Archaea found in humans?1. Oral cavity
2. Torso
3. Intestine
4. Vagina - 20Halophiles1. Extremophiles that can occur in environment with high salt concentrations
2. Salt-loving
3. Polyphyletic: Occurs outside of Archaea
4. Some capable of light-driven ATP synthesis
5. Survive by increasing osmolarity of cell by compatible solutes and influx of K+ - 21Salt-In StrategyAll enzymes and structural cell components must be adapted to high salt concentrations to ensure proper cell function
- 22Extreme Thermophiles1. Occur in environments with high temp
2. Enzymes can function at high temp
3. Membranes stable at high temp
4. Includes obligate and facultative - 23Adapting to High Temp1. Has high concentration of cytoplasmic solutes and heat-stable molecules
2. No change in amino acid composition
3. Highly hydrophobic cores
4. Increased ionic interaction on protein surfaces
5. Chaperonins: proteins that refold partially denatured proteins
6. DNA stability by polyamines and archaeal histones - 24Phyla of Archaea1. Based on 16S rRNA
2. Euryarchaeota
3. Crenarchaeota
4. Karoarchaeota
5. Nanoarchaeota - 25Euryarchaeota1. Largest phylum
2. Means "Broad-ranging archaea
3. Dominated by methanogens
4. Diverse habitats and physiologies
5. Includes methanogens, halophiles, thermophilic aerobes and anaerobes - 26Crenarhaeota1. Means scalloped archaea
2. Irregular in shape
3. Synthesize tetraether lipid called crenarchaeol: number of rings increases with temp and therefore more stable
4. Diverse habitats
5. Abundant in marine systems
6. Lack histones
7. Include thermophiles
8. Gram negative
9. Sulfolobales (species) - 27Sulfolobales1. Species that oxidize sulfur to sulfuric acid
2. Found in hot springs
3. Thermoacidophile: 80C and pH 3 - 28Karoarchaeota1. Only known from sequence
2. Only in extremely hot habitats - 29Nanoarchaeota1. Nanoarchaeum: small, parasitic, early-branching members of Archaea
2. Lack genes for all but core molecular processes
3. Depend on host, Ignicoccus (Crenarchaeota) for most cellular needs - 30Archaeal Viruses1. Major evolutionary fore shaping cellular life
2. Have DNA genomes and infect hosts (Crenarchaeota)
3. Morphologically more diverse than bacteria
4. Found in extreme hydrothermal and hypersaline environments
5. Yield few significant matches to sequence in public sequence database
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- Evolution, Ecology, and Diversity (Exam 1) FlashCards sobre Archaea, criado por Amanda Vang em 09-10-2017.
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- Amanda Vang
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