Prokaryotes And The Origins of Metabolic Diversity

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Prokaryotes And The Origins of Metabolic Diversity

• Kingdom Monera

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The Oldest Organisms

• Oldest fossils go back 3.5 bya
• Chemical cycles evolved in prokaryotes
• Wide range of modes of nutrition
• Est. diversity of up to 4 million species
• Two main brances are archaea and bacteria

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The Three Domains
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Comparing Domains
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Three Common Shapes
Spheres - Cocci
Rods - Bacilli
Helices Spirilla, spirochetes
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Classification By Gram Stain
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Gram Positive and Gram Negative Bacteria
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Pilli

• Allow bacteria to attach to a substrate
• Allow for exchange of plasmids during conjugation
• Not present in all bacterial groups

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Some Bacteria Are Motile

• Bacilli may move using one or more flagella
• Narrower than eukaryotic flagella
• Lack membrane covering
• Not a 92 pattern
• Exhibit taxis chemo or photo

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Flagella
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Reproduction and Genetic Recombination

• Asexual reproduction by binary fission 20min.
  in log phase growth
• Three mechanisms of genetic recombination
• 1. transformation
• 2. conjugation
• 3. transduction
• Mutation is the major source of genetic variation

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Bacilli Produce Endospores

• Bacillus anthracis
• Resistant capsule
• Survives many attempts destroy it
• Requires sterilization with heat and pressure
• Steam at 15 lbs. per sq. in. for at least 20 min.

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Nutrition and Metabolic Diversity
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Evolution of Photosynthesis
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Archaea

• Methanogens use CO2 to oxidize H2 into CH4
• Exteme halophiles (Bacteriorhodopsin is their
  photosynthetic pigment. Purple color)
• Extreme thermophiles Oxidize sulfur for energy
  at deep-sea thermal vents at 105ºC

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Ecological Impact of Prokaryotes

• Decomposers Recycle chemical elements between
  biological and physical components of the
  ecosystem
• Fix carbon (as CO2) and nitrogen (as NH3)
• Produce O2 (cyanobacteria)
• Symbiotic
• mutualism cyanobacteria in root nodules
• commensalism bacteria in/on the body
• parasitism pathogenic bacteria
• Streptomyces Source of our antibiotics

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Kochs Postulates

• Find the same pathogen in each diseased
  individual.
• Isolate pathogen from diseased individual and
  grow it in pure culture.
• Induce disease using pure culture.
• Re-isolate pathogen from individuals in which
  disease was induced from pure culture.
• Doesnt work for all pathogens (Treponema
  pallidum, the cause of syphilis, cant be
  cultured on media)

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Exotoxins

• Proteins secreted by prokaryotes
• Clostridium botulinum botulism (botox)
• Vibrio cholerae Cholera (severe diarrhea)
• E. coli Travellers diarrhea

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Endotoxins

• Components of the outer membranes of certain
  gram-negative bacteria
• Genus Salmonella Causes food poisoning
• Actinomycetes Fungus-like prokaryotes
• 1. Mycobacterium sp. (Tuberculosis leprosy)
• 2. Streptomyces sp. (Antibiotics)

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Benefit to Society

• Remove pollutants from soil, water, or air
• Oil spills
• Sewage treatment
• Production of drugs by genetic engineering
• Prevention of freeze damage to crops
• Antibiotic production