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Prokaryotes vs. Eukaryotes Prokaryotes vs. Eukaryotes The Endosymbiotic Theory Why study prokaryotes? Why study prokaryotes? They cause disease Why study prokaryotes? They cause disease True, but most prokaryotes want nothing to do with humans Why study prokaryotes that don’t cause disease? Why study prokaryotes that don’t cause disease? Prokaryotes were the first living organisms on the planet Prokaryotes live everywhere life is possible Prokaryotes live everywhere life is possible Prokaryotes live everywhere life is possible Enzymes useful for medical or industrial uses may be discovered in prokaryotes living in extreme environments Prokaryotes likely constitute the largest component of the planet’s biomass Prokaryotes likely constitute the largest component of the planet’s biomass Entire ecosystems depend on their activities Prokaryotes play a vital role in the ecosystem Prokaryotes are required for the cycling of nutrients throughout the environment The carbon cycle The nitrogen cycle The sulfur cycle The iron cycle Louis Pasteur Louis Pasteur Discovered that wine was souring due to bacterial contamination Louis Pasteur Discovered that wine was souring due to bacterial contamination Specific microorganisms are responsible for specific changes in chemical compounds Louis Pasteur Discovered that wine was souring due to bacterial contamination Specific microorganisms are responsible for specific changes in chemical compounds Sugar ethanol (yeast) Sugar lactic acid (bacteria) Louis Pasteur and Robert Koch Robert Koch Aseptic slices of potato used as first solid media Robert Koch Aseptic slices of potato used as first solid media Gelatin used as solidifier Agar suggested by wife of Koch’s assistant Robert Koch Petri invented dishes to pour agar into Many microorganisms either cannot grow in artificial media or are at very low concentrations compared to other microorganisms Many microorganisms either cannot grow in artificial media or are at very low concentrations compared to other microorganisms Sergei Winogradsky and Martinus Beijerinck developed enrichment techniques and selective media Sergei Winogradsky Discovered that bacteria can oxidize iron, sulfur and ammonium to obtain energy Discovered that some bacteria can fix CO2 like photosynthetic plants Winogradsky column Used to isolate photosynthetic organisms Winogradsky column Used to isolate photosynthetic organisms Column packed with mud, sulfur, carbonate and cellulose Column exposed to light Winogradsky column Different organisms grow at different layers Samples from different layers plated on selective media Prokaryotes often live in complex communities Biofilms Prokaryotes often live in complex communities Microbial mat Stromatolites