Flashcards
Archaea
Cards in this deck (19)
- 1If you had an unknown bacteria, how would you work out what it is?Look at morphology on a macroscopic and microscopic plane. Also look at physiological and metabolic properties lime enzymes and genes. Clinical diagnostics like a API strip also can identify molecules with died reagents.
- 2How can we work out bacteria's ancestry being as there is a very poor fossil record of bacteria?All bacteria are related by descent. Sequence its genome. 16S rRNA gene is present in all organisms to be compared and has the same function. It is stable in some regions but variable in others. Closer related bacteria will have more similar variable regions.
- 3Key features of archaea?No membrane enclosed nucleus, no membrane enclosed organelles, circular chromosome, no paired chromosomes, 70S ribosomes, no introns in genes, genes are in operons, can grow above 70 degrees C. Are all microorganisms.
- 4Where can archaea inhabit?Extremes of salt, temperature, pH. Also in marine and freshwater environment and animal guts
- 5Two groups of archaea looked at?Crenarchaeota (hyperthermophylic species, often chemolithotrophic, autotrophic)
Euryarchaeota (physiologically diverse and many are extremophiles) - 6What are hyperthermophiles?They are isolated from geothermal springs and soils. There are temperatures of 100 degrees C or more. Some live in sulfur rich springs with pH from mildly alkaline to pH 1. Also found in hypothermal vents under the sea where water is up to 500 degrees c and under pressure
- 7What is Sulfolobales?Sulfolobus acidocaldarius. It grows in sulphur-rich acidic hot springs. Is aerobic chemolithotroph that oxidizes reduced sulphur or iron. Is at 90 degrees c and at a pH of 1-5. They are spherical/lobed organisms and adhere to sulphur crystals.
- 8How do Sulfolobales survive such high temperatures?Their S-layer helps. Is a regularly spaced array of protein subunits that self assemble into porous lattice. Anchored into archaea CM in sulfolobales.
- 9What is Desulfurococcales?Example: Pyrolobus fumarii. Optimum growth at 106 degrees C. Lives in the walls of black smokers. Has protein S layer. Membrane composed of diglycerol tetraethers. Is autotrophic and a facultative aerobe. Obligate H2 chemolithotroph. NO3- is used as terminal acceptor in anaerobic conditions.
- 10How have archaea adapted to life ayt high temperatures?There should be an instability of biomolecules at high temperatures but proteins are surrounded by 'heat shock proteins' known as molecular chaperones. They are proteins which refold partially denatured proteins. Produced in very high amounts in thermosome.
- 11How do archaea respond to problems caused to the DNA from high temperatures?Positive supercoils are induced into DNA by reverse DNA gyrase to protect it. This means it is harder to separate DNA strands for replication so transcription is much more complex in archaea. Also, DNA binding proteins stabilise minor grooves in DNA.
- 12Are all Crenarchaeota found in hyperthermal environments?No, some can be found in nutrient poor marine environments and can survive in very cold seawater and ice microchannels. They are floating but can be detected by small subunit rRNA. Probably involved in carbon cycle as can carbon fix.
- 13What is Helobacterium salinarum?A Euryarchaeota that is an extreme halophile (extremely high salt concentration). Typically need at least 1.5 moles of NaCl for growth. Are found in sea salt evaporation ponds, salt lakes and artificial saline habitats like salted food.
- 14What issues will be faced from high saline concentrations?Osmotic forces will be tampered with and there will be high solute levels inside the cell
- 15How are these problems combated?Maintain positive water balance by pumpking K+ into the cells so higher K+ inside than Na+ outside. Glycoprotein S - layer stabilised by Na+ and cellular proteins composed of more acidic amino acids that are more soluble at high solute concentration.
- 16What are methanogens?Produce methane (CH4) as a product. Do this to produce ATP. Production of methane for this is unique to archaea. Important in degradation of organic matter and are found in sediment low in O2 like marshes and swamps, animal digestive tracts and hydrothermal vents. Are obligate anaerobes.
- 17Example of methanogen?Methanobacterium (don't be fooled by bacterium being in the name - it is an archaea). Has pseudomeurin in its cell wall.
- 18What kind of amino acids do you get in archaea?Only L amino acids
- 19Things in common between Archaea and Eukarya?Neither have peptidoglycan cell wall. Both have histones. Archaea has a complex RNA polymerase and Eukarya have three complex RNA polymerases. Both have TATA box promoter structures and Met as the initiating tRNA
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- Introduction to Microbiology Flashcards on Archaea , created by Emma Lloyd on 20/05/2018.
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