Bio Lecture 8 Origin of Life: Prokaryotes

Domain Bacteria/ Archea

• Appx. 30,000 described species

• tens of millions may exist

• Little anatomical diversity

• Diversity found in metabolism

Comparing Bacteria, Archaea, Eukarya

Bacteria Archaea Eukarya

Nuclear env. Absent Absent Present

Membrane Absent Absent Present

encl. org.

histones w/ dna Absent Some Present

Circ. Chromo. Present Present Absent

Scope of 3 Domain differences

Eukarya as different from archaea as bacteria… all 3 equally different

Phylogenetic Relationships

Archaea, bacteria very ancient

Bacteria → Archaea

Eukarya arose via ENDOSYMBIOSIS of bacteria & archaea

Domain Archaea phylums

Euryarchaeota

Korarchaeota

Crenarchaeota

Nanoarchaeota

Phylum Euryarchaeota species

• Methanogens (anaerobes)

  • In marshes, termite guts, cows

• Halophiles (Salt tolerant)

  • Photoheterotrophs: Photophosphorylation to produce ATP absorb complex organics

• Thermoacidophiles (hot, acid environments)

  • Thermus aquaticus source of TAQ polymerase

Phylum Crenarchaeota

• Hyperthermophiles (temps above boiling)

• Cold-dwelling crenarcheotes (sea-water and sea-ice)

• Chemolithotrophs (energy from oxidizing inorganic compounds H2 FeS2)

• Chemoorganotrophs (energy from oxidizing organic compounds)

Phylum Korarchaeota

Know they exist because we have sequnced DNA

• Circular w/ histones

• Unknown metabolism

Phylum Nanoarchaeota

Parasitic on Archaean

Domain Eubacteria (gram pos. vs. gram neg.)

Gram Negative bacteria (double plasma membrane, thin peptidoglycan layer)

• Cyanobacteria

• Spirochaetes

Gram Positive bacteria (thick peptidoglycan layer single plasma membrane)

Proteobacteria

Alpha proteobacteria

• Endo-parasitic of eukaryotic cells

• Mark DNA

Chlamydias

Chlamydia

Spirochetes

Tepanema

• Syphilis

Borrelia

• Lyme disease

Gram-Positive bacteria

Staphylococcus

Streptococcus

Biogeochemical Cycles

Cycle in which elements cycle from abiotic realm (non-living) to biotic (living)

• Carbon cycles

• Oxygen cycles

• Nitrogen cycles

Nitrogen Cycles

Nitrogen → Nitrogen-fixing bacteria → NH3 → Nitrifying bacteria → NO3- → Denitrifying bacteria →N2

N2 fixing

Nostoc, Anabaena, Rhizobium

Nitrifying

Nitrosophorias, nitro bacter

Denitrification

Pseudomonas

Decomposer

Pseudomonas, Bacillus (makes gangrene)