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Prokaryotes
Archaea & Bacteria Domains
C23, pp461-476
Prokaryotic facts
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Most numerous organisms on Earth
Earth’s earliest fossils (3.5 x 109 yrs old)
Lack membrane-bound organelles
rRNA analysis shows Archaea linked more to
Eukaryotes than to Bacteria
• Generally have cell wall, cell membrane,
cytoplasm with ribosomes, DNA, & small ions/
molecules
Archaea vs. Bacteria
• Cell walls
– Bacteria have peptidoglycans. Archaea don’t.
• DNA
– Archaea have introns. Bacteria don’t.
• Groups
– A: Methanogens, halophiles, thermoacidophile
– B: Bacilli, cocci, spirilla; gram-pos & gram-negative
Bacterial Cell Characteristics, p468
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Capsule: protects & aids in attachments
Cell wall: protects & gives shape
Cell membrane: control passage in/out of cells
Plasmid: carries genes in small DNA loop
Endospore: contains DNA; thick-coated
Pilus: attachment during conjugation
Flagellum: propels cells
Gram-neg outer membrane: deflect antibiotics
Bacteria Nutrition, p469
• Autotroph
– Photoautotroph (uses sunlight; gets C from CO2)
– Chemoautotroph (gets energy from inorganic cpd;
gets Carbon from CO2)
• Heterotroph
– Photoheterotroph (uses light energy but get
Carbon from other organisms
– Chemoheterotroph (gets energy & C from other
organisms)
Prokaryotic Reproduction, p471
• Single circular loop of DNA is copied
• Binary fission yields 2 identical daughter cells
• Exchanging DNA
– Transformation
• Gets DNA from its outside environment
– Conjugation
• Gets DNA from other prokaryote via sex pilus
– Transduction
• Virus copies piece of host DNA & transfers it to others
Prokaryotic Habitats, p470
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Obligate anaerobes = no O2 allowed
Facultative anaerobes = + O2 is OK
Obligate aerobes = O2 necessary
Psychrophilic = cold-loving (0oC – 20oC)
Mesophiles = average (20o-40oC)
Thermophiles = hot-loving (45o- 110oC)
Acidophiles = pH at or below 6.0
– Most prefer neutral pH range of 6.5 – 7.5
Bacterial disease, p472
• Disease
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Anthrax
Botulism
Tetanus
Cholera
Gonorrhea
Dental caries
Food poisoning
Lyme disease
• Bacterium
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Bacillus anthracis
Clostridium botulinum
Clostridium tetani
Vibrio cholerae
Neisseria gonorrhoeae
Streptococcus mutans
Salmnella typhimurium
Borrelia burgdorferi
Bacteria in Industry
• Foods
– Fermentation  buttermilk, sour cream, yogurt
– Cheeses, sauerkraut, pickles, kimchi, coffee, soy
• Medicine
– Acetone, acetic acid, enzymes, antibiotics, insulin
• Agriculture
– Endotoxins as insecticides
• Bioremediation = degrade petroleum