Prokaryotes vs. Eukaryotes. The Endosymbiotic Theory.

Prokaryotes vs. Eukaryotes

The Endosymbiotic Theory

Why study prokaryotes?


They cause disease


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

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


Specific microorganisms are responsible for specific changes in chemical compounds

Louis Pasteur


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

Prokaryotes vs. Eukaryotes. The Endosymbiotic Theory.

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