The Origin and Evolution of Microbial Life

Stromatolites

Prokaryotes

Review of Prokaryotes

• Lack nucleus and other membranous organelles

• Majority of DNA is a single large ring

• Amount of DNA transferred in reproduction varies

• Reproduce via binary fission

• Posses cell wall different from plants

Earliest Life

Bacteria & Archaea

Prokaryote Shapes

Modes of Nutrition

Archaea Live in Extreme Environments

Prokaryotic Survival Structures

• Cell wall

• Capsule

• Flagella

• Pili

• Endospores

Flagella

Pili

Endospores

Robert Koch

Koch’s Postulates

So, What Are We Getting At?

• How might Eukaryotic life have arisen?

• 2 theories– Infolding of Plasma membrane– Endosymbiotic hypothesis

Membrane In-Folding Theory

Endosymbiotic Theory

Protists

• 4 Major Groups– Protozoans (first animal)– Slime molds– Unicellular algae– Multicellular algae

• Earliest protists were ancestral to plants animals and fungi

Protozoans

• Amoebas

• Flagellates

• Apicomplexans

• Cilliates

Amoebas

Flagellates

Apicomplexans

Dinoflagellates

Cilliates

Slime Molds

• Single and multi-cellular life stages

• Thrown in with amoebas into amoebozoa– Use pseudopodia

• 2 major types– Cellular slime molds– Plasmodial slime molds

Cellular Slime Molds - 1

Cellular Slime Molds - 2

Cellular Slime Molds - 3

Plasmodial Slime Molds - 1

Plasmodial Slime Molds - 2

Plasmodial Slime Molds - 3

Stramenopiles

• Group named for use of “hairy” flagellum

• 3 major types– Diatoms– Brown algae– Water molds

Diatoms

Brown Algae

Green Algae

Red Algae

Multicellular Green Algae

Evolution of Multicellularity