BIOL 2004 Lecture Notes - Lecture 19: Endomembrane System, Golgi Apparatus, Cytokinesis
Document Summary
Some grow >90 degrees (hyperthermophiles); even ~120 degrees: many thermophiles are lithoautotrophs. Habitats for thermophilic archaea: primarily, geothermal sites. Deep in earths crust, etc: sources of h2, h2s, sulfur. E. g. eat h2 with s as electron acceptor. Surviving extreme temperatures: thermostable enzymes and other proteins. Structurally stable (& active) at high temperatures: membranes increased integrity and rigidity. Archaeal membrane lipids more stable in first place. Additional e. g. : tetraethers in some archaea: dna sptabilization. Induces positive supercoils: increases dna stability: ribosomes (ribosomal rna) Very high g+c content (more h-bonds in stem regions) Methanogens: methane as end product of energy metabolism, most euryarchaeota are methanogens, obligate anaerobes (usually very strict anaerobes, most re found in low-oxygen, but otherwise normal environments, some are also thermophiles, methanogenesis as an energy pathway. Example substrates: h2, acetate (e. g. fermentation end products . Example: 4h2 + co2 2h2o + ch4. Marshes and other wetlands (inc. rice paddies)
