Bacteria and Archaea The Prokaryotic Domains Tree of Life The Bacterial Cell Prokaryotic Shapes Sizes Thiomargarita namibiensis One of the largest bacteria Most of the cell is filled with a large vacuole Cytoplasm is a thin film around the periphery Myxobacterium Horizontal Gene Transfer Bacterial genomes are smaller than eukaryotic genomes A process by which bacteria obtain new genes from other bacteria Three methods Conjugation Transformation Transduction Viruses Conjugation Antibiotic resistance genes Used in the laboratory Transformation Discovered when harmless strains of bacteria causing pneumonia could be transformed into disease causing strains through exposure to dead cells of the virulent strain Transduction Sometimes genetic material from the bacterial host is incorporated into the viral DNA upon assembly of the particles Characteristics of Archaea Similarities to Bacteria are No membrane bound organelles Single circular chromosome Cell size is limited by diffusion Differences are Membranes have a unique lipid composition compared to Bacteria and Eukarya No peptidoglycan in the cell walls Many inhabit extreme environments An Expanded Carbon Cycle Oxidation reduction chemistry transfer of electrons Reactions in which electrons are removed from oxidation or added to reduction a molecule Reactions happen in pairs Photosynthesis Respiration CO2 is reduced to form carbohydrates Carbohydrates are oxidized to CO2 O2 serves as electron acceptor In all known photosynthetic eukaryotes photosynthesis is oxygenic O2 producing Respiration in most eukaryotic cells is aerobic uses O2 Not all An extended Carbon Cycle Microbial Mats Layers of Microbial Mats Oxygenic Photosynthetic bacteria Produces Oxygen Anoxygenic photosynthetic bacteria Photosynthesizes without producing O2 Bacteriochlorophyll Anaerobic respiration Does not use O2 to drive the reactions no light photosynthesis Fermentation Acquiring Energy and Carbon Energy Carbon Sun Phototrophs Chemical compounds Chemotrophs humans are this Inorganic molecules CO2 Autotrophs Organic molecules glucose Heterotrophs humans Photoautotrophs plants algae cyanobacteria Chemoheterotrophs animals fungi prokaryotes humans Photoheterotrophs microorganisms Chemoautotrophs microorganisms Photoheterotrophs Use energy from sunlight to make ATP but do not reduce CO2 to make their own organic molecules Rely on organic molecules from the environment as a source for carbon Allows the organisms to use all the absorbed light energy to make ATP Microorganisms such as heliobacteria and most green sulfur bacteria Chemoautotrophy Unique to prokaryotes H2 H2S and Fe2 Sulfur Cycle Plants take up 2 from soil and SO4 reduce it to H2S Chemoautotrophs H2S O2 SO4 2 Anoxygenic photosynthesis Use electrons from H2S to form carbs Nitrogen Cycle Anammox NH4 NO2 N2 2 H20 Prokaryotic Phylogeny Phylogeny of Whole Genomes Proteobacteria Most diverse bacterial group Defined by rRNA sequence similarities Includes Chemoautotrophs Bacteria that respire using SO42 NO3 or Fe3 Some of our worst pathogens Rickettsias vibrios salmonellas Escherichia coli Photosynthetic Bacteria Cyanobacteria Single branch on the tree Anoxygenic photosynthesis Purple bacteria Heliobacteria Phylogeny of Archaea Acid loving Archaeons Acid mine drainage pH between 1 2 Picrophilus torridus grows optimally at pH 0 7 Euryarchaeote Archaeons Methanogenic archaeons Generate natural gas methane as a by product of fermentation or chemoautotrophic metabolism light Halophilic archaeons Photoheterotrophs that use bacteriorhodopsin to absorb Archaeons in the Ocean Thaumarchaeota Chemoautotrophs that derive energy from the oxidation of ammonia Evolutionary History Fossils Stromatolites Evolution of cyanobacteria Accumulation of oxygen in the atmosphere and the oceans Coevolution Nitrogen fixing bacteria associated with soy bean roots Methane producing bacteria in the rumen of cows Human Microbiome Microbiota Bacteriochlorophyll
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