Prokaryotes Protists Photosynthesis Endosymbiosis Reconstructing the evolution of living things Systematists study evolutionary relationships Look for shared derived different from ancestor traits to group organisms Evidence used morphology development and molecular data especially DNA sequences Ch 28 29 26 February 2009 ECOL 182R UofA K E Bonine 1 2 Why can t we figure it out perfectly More distant history is obscured by more changes Among oldest lineages of Bacteria and Archaea in particular lots of lateral gene transfer Makes it difficult to infer relationships from phylogeny of single genes trypanosomes red blood cells 3 4 Early prokaryote fossil Diversity of Prokaryotes Bacteria Archaea 5 6 1 Life can be divided into 3 domains What are microbes Only a minority make us sick Robert Koch Germ Theory of Disease In ordinary English might be anything small 3 8bya bacteria yeast protists viruses 1 5bya Prokaryotes bacteria archaea In science classify by evolutionary relationships 7 Eukarya Prokaryote was ancestral and only form for billions of years 8 Scheme has been revised before Haeckel 1894 Three kingdoms Plantae Animalia 9 Woese 1977 Six kingdoms Woese 1990 Three domains Eubacteria Bacteria Archaebacteria Archaea Monera prokaryotes Protista are Prokaryotes monophyletic paraphyletic polyphyletic paraphyletic Whittaker 1959 Five kingdoms Protista Protista Fungi Fungi Plantae Plantae Animalia Animalia Eukarya modified from Wikipedia 10 Unique to Prokaryotes Shared by all 3 domains Circular chromosome Genes organized into operons NO Glycolysis use glucose to get ATP Semiconservative DNA replication 2 strands in double helix during replication each daughter cell gets one strand from parent other is new DNA encodes polypeptides Polypeptides produced by transcription and translation according to genetic code Plasma membranes and ribosomes nucleus translation of mRNA into protein begins before transcription of DNA into mRNA is complete organelles cytoskeleton meiosis Genes can still get moved around in 11 other ways both within and between species The latter is horizontal gene transfer Antibiotic resistance can spread in this way 12 2 Divide by fission 26 02 Prokaryotes are everywhere All around us and in us too Way more bacteria archaea on your skin in your intestinal tract than you cells WE ARE HABITAT 3x1028 in ocean vs visible stars in universe Some survive extreme heat alkalinity saltiness Bottom of the sea Rocks more than 2km into Earth s solid crust Salmonella enteritidis 360x real speed replicate in 30 min http life8eiml sinauer com Videos Video 26 02 mpg 13 What do they look like Biofilms Predominantly unicellular spheres coccus cocci rods bacillus bacilli 14 curved spiral may be found singly or in 2D 3D chains plates blocks multicellular each cell is viable independently 15 Many prokaryotes and some other microbes lay down a gel like substance on a surface This matrix traps others forming a biofilm Biofilms can make bacteria difficult to kill Pathogenic bacteria may form a film that is impermeable to antibiotics for example Dental plaque is a biofilm 16 Most common bacterial motion is via flagella Bioluminescence Fibril of flagellin protein plus a hook and basal body Some bacteria make light Useful for getting into a new fish gut Rotates about its base 17 Different from eukaryotic flagellum which beats 18 3 Cell wall differences seen by Gram stain Exploiting unique bacterial features Gram positive bacteria dense peptidoglycan cell wall Gram negative bacteria thin peptidoglycan layer behind outer membrane Peptidoglycan cell walls unique to bacteria not found in eukaryotes or archaea Many antibiotics disrupt cell wall synthesis This affects only bacteria and has little or no effect on eukaryotic cells 19 20 Morphology gives only limited view of bacterial diversity Bioremediation Hydrogen Production Huge diversity in metabolic pathways oxygen tolerance energy source carbon source nitrogen and sulfur metabolism Clean up oil spills toxins Produce chemicals we find useful Enrichment Cultures grow microbes under variable conditions and see which thrive 21 6 nutritional categories energy carbon 1 6 nutritional categories energy carbon 5 Chemoorganoautotrophs Photoautotrophs energy from light carbon from CO2 energy from other organisms carbon from CO2 2 Photoheterotrophs energy from light C from other organisms 6 Chemoorganoheterotrophs energy and carbon from other organisms most known prokaryotes all animals fungi many protists 3 Chemolithotrophs energy from oxidizing inorganic substances carbon from CO2 some bacteria many archaea 4 Chemolithotrophic heterotrophs energy from oxidizing inorganic substances carbon from other organisms 22 3 ways to get energy x 2 ways to get carbon 6 nutritional metabolic categories 23 24 4 Prokaryotic Metabolic Variety Evolution of Photosynthesis in Cyanobacteria Carbon Source 6 Metabolic Categories Energy Source Photoautotrophs light CO2 Photoheterotrophs light other organisms Chemolithotrophs oxidizing inorganic substances CO2 Chemolithotrophic heterotrophs oxidizing inorganic substances other organisms Chemoorganoautotrophs other organisms CO2 Chemoorganoheterotrophs other organisms other organisms 25 26 OXYGEN Figure 27 11 Cyanobacteria Part 2 None in atmosphere for first 2 3 billion years Cyanobacteria evolved photosynthesis oxygenic ATP water oxygen 27 Aerobic more efficient than anaerobic 28 Oxygen Early earth had little free oxygen O2 2 5 bya prokaryotes evolved ability to split 2H2O 4H O2 4e Electrons used to reduce CO2 and make organic compounds Stealing electrons O2 was a waste product 29 capturing light energy producing high energy compounds 30 5 Figure 8 13 The Calvin Benson Cycle Base of Global Ecosystem Then make glucose and other sugars 31 Oxygen generating cyanobacteria form rocklike structures called stromatolites 32 Oxygen Oxygen was poison when it first appeared Organisms evolved not just to tolerate oxygen but to thrive Aerobic metabolism faster and more efficient 33 34 Increasing oxygen in atmosphere 35 36 6 Aerobic vs anaerobic metabolism 1 Oxygen is toxic to obligate anaerobes 2 Facultative anaerobes can shift between anaerobic metabolism such as fermentation and the aerobic mode cellular respiration 3 Aerotolerant anaerobes don t use oxygen but aren t damaged by it 4 Obligate aerobes cannot survive without oxygen Nitrogen and sulfur metabolism Some bacteria use oxidized inorganic ions such as nitrate nitrite or sulfate