原核生物新陈代谢.ppt

* * * * * * * * Photoautotrophism Photoheterotrophism Chemoautotrophism Chemoheterotrophism Which of these metabolic pathways is Sulfolobus demonstrating? √ Hint: Organic chemicals for energy Organic chemicals for carbon How do Archaea tolerate the heat? Proteins stabilized by more ionic bridges between amino acid r-groups and more-hydrophobic core amino acids Heat shock protein (chaperonins) refold denatured proteins…Pyrococcus 121°C for 1 hour! DNA depurination reduced by presence of 2,3-diphosphoglycerate. DNA supercoiling by reverse gyrase reduces denaturation Sac7d in Sulfolobus is a minor groove protein increases the DNA melting temperature by 40°C Histone-like proteins help stabilize DNA as well Heat-resistant di-bi-phytanyl diether lipid membranes (monolayer) prevent delamination of membrane Cell Membrane Structure O O O O R R O O O O R R Composed of diglycerides R group may be phosphate, sulfate, or sugar Long chain branched hydrocarbon (not fatty acid) Hydrocarbons may be C20 or C40 If C20, the membrane is a bilayer: If C40, the membrane is a monolayer: In some species, the membrane is a mixture of both C20 and C40 diglycerides forming a mixed mono-/bi-layer. The C40 diglycerides prevent the bi-layer from de-laminating! http://www.molgen.mpg.de/~ag_ribo/ ag_franceschi/franceschi-projects-30S.html Not all thermophiles are archaeons! Thermus aquaticus http://sci.agr.ca/crda/images/BACTERI1.JPG Gram negative eubacterium Thermophile isolated from Yellowstone Hot Spring Optimum temperature 85°C Stability of macromolecules excellent Enzymes for research or commercial use Taq polymerase is the enzyme of PCR (Polymerase Chain Reaction) Lives near cyanobacteria which produce CH2O to feed Thermus Photoautotrophism Photoheterotrophism Chemoautotrophism Chemoheterotrophism Which of these metabolic pathways is Thermus demonstrating? √ Hint: Organic chemicals for energy Organic chemicals for carbon /temp/image/1Yellowstone%20National%20Park4.jpg Yellowstone Nat