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Prokaryotes Archaea & Bacteria Domains C23, 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