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The Prokaryotes EUBACTERIA (Bacteria) ARCHAEBACTERIA (Archaea) EUKARYOTES (Eukarya) • 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 Bacteria—what do they look like? Ecological Importance of Prokaryotes • Decomposition • Nitrogen fixation • Mutualistic relationships • Parasitic relationships • Commercial uses Treponema pallidum, a spiral-shaped bacteria which causes Syphilis in humans Prokaryotic Fission Rods, spheres, spirals, vibrio Fig. 21-5, p.335 1 Bacterial Diversity • Photoautotrophic – Aerobic (Cyanobacteria) – Anaerobic (Green bacteria) • 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. • Chemoautotrophic – Important in nitrogen cycle • Chemoheterotrophic – Largest group • 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 Archaebacteria • Bacteria are also important to numerous industrial processes, – wastewater treatment – industrial production of antibiotics and other chemicals. EUBACTERIA (Bacteria) ARCHAEBACTERIA (Archaea) EUKARYOTES (Eukarya) Methanogens Methanogens Extreme halophiles Extreme thermophiles Fig. 21-11b, p.340 2 Extreme Thermophiles Extreme Halophiles Fig. 21-12a, p.341 Fig. 21-12b, p.341 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. 3