Prokaryotes vs. Eukaryotes

The Endosymbiotic Theory

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?

Prokaryotes were the first living organisms on the planet

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

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

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

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 CO 2 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