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Prokaryotes
Archaea & Bacteria DomainsC23, pp461-476
Prokaryotic facts
• 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
• 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
• 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– Anthrax– Botulism– Tetanus– Cholera– Gonorrhea– Dental caries– Food poisoning– Lyme disease
• Bacterium– 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