Prokaryotes

Chapter 19

Prokaryotes! • The small wonder… First inhabited

the earth 3.5 bya!• Continued to rule alone for 1.5 billion

years until they gave rise for more complex organisms

• Still exist today (bacteria) and are still one of the most fierce predators, as well as important helpers associated with human health.

• Have no nucleus… Even though in two different domains they are very similar in morphology

• Generally single celled

Y. pestis (cause of bubonic plague)

ESCHERICHIA COLI is a type of bacteria that lives in the intestinal tract, aiding the digestive process by suppressing the growth of harmful bacteria and synthesizing vitamins

Prokaryotes are broken into two major groups… diverged a long time ago

Archaea• Has its own rRNA

sequences (some match Eukaryotes)

• Use several RNA polymerase molecules similar to eukaryotes

• No true peptidoglycan• Some Carbon chains,

mostly branched

Bacteria• Has unique rRNA

sequences• Replicates with one

kind of RNA polymerase• Can have a

Peptidoglycan cell wall (Gram Stain)

• Unbranched carbon chains in the membrane lipids

Prokaryotes are divided by the way they get nourishment

• Earliest life needed to be autotrophs (make their own food). Need Energy (make ATP… to do so they need a carbon source!)– Photoautotrophs: Energy from

Sunlight… carbon from CO2 (Cyanobacteria… No Archaea just bacteria)

– Chemoautotrophs: Consume Inorganic matter and break their bonds for energy… get their carbon from CO2 (many Archaea metabolize this way)

More Prokaryote divisions• Once some Autotrophs existed

organisms can start eating other organisms (heterotrophs)– Photoheterotrophs: Energy from

sunlight, Carbon from organic materials (some purple and green bacteria)

– Chemoheterotrophs: Get energy by breaking bonds of Organic molecules, also get their carbon from organic molecules (similar to animals… largest group, includes E. coli and SOME Archaea)

Purple bacteria

Anthrax (Bacillus anthracis )