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