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EUBACTERIA(Bacteria)
ARCHAEBACTERIA(Archaea)
EUKARYOTES(Eukarya)
The Prokaryotes
• Only two groups
• Archaebacteria and Eubacteria
• Arose before the eukaryotes
Prokaryotes—characteristics
• Single-celled
• Metabolically diverse
• No nuclear membrane
• Single chromosome
• No organelles
• Very small
• Cell wall
• Flagella rotate like propellers
• Pili extend from the cell surface for
adhesion or motion
Ecological Importance of
Prokaryotes
• Decomposition
• Nitrogen fixation
• Mutualistic relationships
• Parasitic relationships
• Commercial usesTreponema pallidum, a spiral-shaped bacteria which causes Syphilis in humans
Bacteria—what do they look
like?
Rods, spheres, spirals, vibrio
Fig. 21-5, p.335
Prokaryotic Fission
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Bacterial Diversity
• Photoautotrophic
– Aerobic (Cyanobacteria)
– Anaerobic (Green bacteria)
• Chemoautotrophic
– Important in nitrogen cycle
• Chemoheterotrophic
– Largest group
• Bacteria, often in combination with yeasts
and molds, are used in the preparation of fermented foods such as:
– cheese, pickles, soy sauce, sauerkraut,
vinegar, wine, and yogurt.
• Bacteria are also important to numerous industrial processes,
– wastewater treatment
– industrial production of antibiotics and other chemicals.
• Some bacteria act as pathogens
– tetanus, typhoid fever, pneumonia, syphilis, cholera, food-borne illness, leprosy, and
tuberculosis(TB).
– In plants, bacteria cause leaf spot, fireblight, and wilts.
– The mode of infection includes contact, air, food, water, and insect-borne microorganisms
EUBACTERIA(Bacteria)
ARCHAEBACTERIA(Archaea)
EUKARYOTES(Eukarya)
Archaebacteria
Methanogens
Extreme halophiles
Extreme thermophiles
Fig. 21-11b, p.340
MethanogensMethanogens
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Fig. 21-12a, p.341
Extreme HalophilesExtreme Halophiles
Fig. 21-12b, p.341
Extreme ThermophilesExtreme Thermophiles
Where Do Viruses Fit?
• Not “alive”?
• Not a cell
• Nucleic acids in protein shell
• Do not grow, do not maintain
homeostasis, and do not metabolize on their own
• Use host cell to replicate
• Lytic and Lysogenic life cycles
Early Stage of Influenza Virus
Viruses• Chicken pox
• H1N1
• Hepatitis
• HIV - human immunodeficiency virus
• Measles
• Mononucleosis
• Mumps
• Respiratory Syndrome (SARS)
• Smallpox
Why don’t antibiotics work for
colds and flu?
Why don’t they destroy your
body’s cells?
Hint: Antibiotics often work by
disrupting the bacteria cell wall.
