Prokaryotes and the nonliving Archaea Bacteria Domains with
Prokaryotes and the nonliving Archaea & Bacteria Domains with Viruses C 2, pp 24 -46.
Prokaryotic facts • Most numerous organisms on Earth • Earth’s earliest fossils (Bacteria 3. 5 x 109 yrs old; Archaean - 2. 7 x 109 yrs ago). • Lack membrane-bound organelles • r. RNA 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. • Sporulation – Some bacteria do. Archaeans don’t. • Groups – A: Methanogens, halophiles, thermoacidophile – B: Bacilli, cocci, spirilla; gram-pos & gram-negative
Bacterial Cell Characteristics • • 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 • Autotroph – Photoautotroph (uses sunlight; gets C from CO 2) – Chemoautotroph (gets Energy from inorganic compound; gets Carbon from CO 2) • Heterotroph – Photoheterotroph (uses Light Energy but get Carbon from other organisms) – Chemoheterotroph (gets energy & C from other organisms)
Prokaryotic Reproduction • Single circular loop of DNA is copied • Binary fission yields 2 identical daughter cells • Exchanging DNA – Lateral gene transfer • Between different species; natural conditions – 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 • • Obligate anaerobes = no O 2 allowed Facultative anaerobes = + O 2 is OK Obligate aerobes = O 2 necessary Psychrophilic = cold-loving (0 o. C – 20 o. C) Mesophiles = average (20 o-40 o. C) Thermophiles = hot-loving (45 o- 110 o. C) Acidophiles = p. H at or below 6. 0 – Most prefer neutral p. H range of 6. 5 – 7. 5
Bacterial disease • 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
Viruses • Nonliving – Noncellular • DNA or RNA inside a protein coat + oily envelope – No organelles for homeostasis, metabolism, or reproduction – May use RNA instead of DNA for heredity • Shapes – Helical – Icosahedral – Complex
Viral Classification • By type of nucleic acid possessed – RNA or DNA • Shape & structure – Viral strains/ serotypes • Organism they infect (host) – Avian influenza – Can jump to new species, however • Place identified – Ebola from Ebola Valley, Congo region, Africa
Viral Diseases • Rhinovirus – Common cold • Influenza virus – Evolve extremely quickly – RNA virus hijack’s host machinery – Survive on moist surface ~ 2 wks • HIV-1 – Retrovirus (injected RNA D host DNA) – Can lie dormant for years
Virus Life Cycle • • Attach to host plasma membrane Be engulfed into host cell Viral coat shed Enters host nuclei for replication Produces viral proteins on host’s ribosomes Nucleic acid is housed in protein New viruses exit cell via budding or cell lysis
Treating Viral Diseases • Antibiotics don’t work • Immune system fights back – with eosinophils & T-helper cells – with fever – But usually overwhelmed eventually • Drug cocktails – Disable viral reproduction – Can have serious side effects
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