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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