Lecture 111. Recall in which environments archaea can be found a. Strict aerobes to strict anaerobesb. All soil and water habitatsc. Associated with plants and animals (no pathogens)d. All temps from < 0º C to >121º Ce. Some live at high salt concentrations- up to saturated NaClf. pH of 0 to 11g. high pressuresh. Placesi. Geysers2. List different energy metabolisms found in archaea a. 5 phylab. chemolithotrophsc. chemoorganotrophsd. Phototrophs- us elight to produce ATPe. Methanogensis3. Explain what discovery Alessandro Volta made a. Bubbles from agitated lake bottoms are flammable in 1776b. Bubble were made of methane4. Explain how Carl Woese came to identify the domain of archaea a. 16s rRNA sequences show 3 domains of life in 1970’s5. Explain how lipids from archaea differ from those in bacteria a. Archaea: ether linked L-glycerolb. Bacteria: ester linked D-glycerol6. Compare and contrast major features of bacteria and archaea a. Archea have no chlorophyll and bacteria dob. Archaea have similar gene expression machinery to eukaryotes not bacteriac. Archaea have no peptidoglycand. Archaea walla resist lysozyme 7. Explain why it is thought that eukaryotes evolved from archaea a. Gene espression machinery8. Explain which features make hyperthermophilic proteins thermostable a. Hihgly hydrophobic coreb. More salt bridges on surface shorter surface loopsc. 3D structures and amino acid contents similar to mesophilic proteins9. Explain how archaeal membrane lipids adapt to high temperatures a. High Pressureb. Chaperonins- other proteins that help proteins fold correctlyc. Ether bonds and isoprene unit and attach the lipid layers together so they can break apart in high heat they make it a monolayer10. List the features that stabilize the DNA of hyperthermophiles a. Reverse DNA gyrase- positive supercoilb. High salt and compatible solute concentrationc. DNA binding proteins wind DNA into compact structuresd. Same GC content11. Recall the minimum salt concentration required for the growth of extreme halophilesa. 1.5 M NaCl (9%) required up to 5.5 M12. Explain the salt-in strategy a. Intracellular ionic concentrations similar to environment13. List adaptive features of extreme halophiles to high salt environments a. Ion pumps Na+ ion pumped out K+ ions pumped inb. Extracellular Na+ stabilizes cell wall glycoproteins, intracellular K+ stabilizes protein and ribosomesc. DNA contains > 60% GC14. Explain the mechanism of proton extrusion by retinal in archaea a. Carotenoid conjugated to bacteriorhodpsinb. Light excitation, trans to cis configuration changec. Coupled to proton translocationd. PMF used for ATP synthesise. PMF also used to pump Na+ out15. Explain why archaea are said to not have photosynthesis a. Use the PMF for energy by light and proton moves and goes through PMFb. No chlorophyll involved so not photosynthesis16. Describe the purpose of methanogenesis, and why it can work a. ATP productionb. H2 is e- donor and CO2 is e- acceptor c. Unusual coenzymesd. CO2 fixation through acetyl-CoA pathwaye. Pushes Na+ out to make ATP17. Explain why methanogenesis is only found in strict anaerobic archaea a. Very oxygen sensitive18. Explain how ATP is produced in methanogens a. Na+ motive pump when sodium is pushed outside the membrane19. Explain why methanogens could have evolved early 20. Describe problems linked to methanogenesis and a beneficial use of methanogenesis a. Impact on global warmingb. Anoxic lake and marsh sediemtnsc. Animal digestive tracts: mammal, termite gutsd. Bovine methanogenesis ;e. Decrease meat productionf. 18% OF GREEN HOUSE GASES g. LANDFILL SEWAGE TREATMENT PLANTS, methane can be harvested for
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