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Notes: Bacteria

Learn about bacteria's general characteristics, different kingdoms, basic structure, growth, reproduction, metabolism, ecological and human importance, antibiotics, diseases caused by bacteria, Griffith's transformation experiment, and controlling bacteria through vaccines, antibiotics, sterilization, and disinfectants.

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Notes: Bacteria

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  1. Notes: Bacteria

  2. General Characteristics • Microscopic, Exist everywhere • Unicellular • Prokaryotic (no nucleus or membrane bound organelles) E. coli is a typical bacterium that lives in the human intestines.

  3. Kingdom Archaebacteria • Autotrophic • Found in extreme environments • Do not have peptidoglycan in cell walls • Instead have unique compounds in cell wall depending on species. Examples: • Methanogens - in oxygen-free environments, like animals’ intestines - symbiosis • Halophiles – in concentrated saltwater • Thermoacidophiles – in hot, acidic waters of sulfur springs

  4. Kingdom Eubacteria • Ecologically diverse • Have peptidoglycan in cell walls. • Heterotrophs - • Decomposers • Parasites • Autotrophs - Cyanobacteria: common in ponds, streams, and moist areas of land.

  5. Cell membrane Ribosome Cell Wall Peptidoglycan Flagellum DNA Pili General Bacteria picture

  6. Basic Structure • No membrane-bound organelles • Small ribosomes • DNA - single circular chromosome • Cell wall (peptidoglycan) • Can be classified by shape & metabolism

  7. Cell Shapes & Arrangements • Spheres: cocci (-us) • Rods: bacilli (-us) • Spiral: spirilla (-um) • Pairs: Diplo- • Cluster: Staphylo- • Chain: Strepto-

  8. Name this bacterium streptococcus

  9. Metabolism • Obligate aerobes require oxygen for cellular respiration • Obligate anaerobes no oxygen, produce energy thru glycolysis/fermentation • Facultative anaerobes can survive with or w/out oxygen

  10. Growth & Reproduction • Some divide every 20 min. • Pop. held in check by food availability & wastes produced

  11. 1. Binary Fission • Asexual • Produces identical cells thru mitosis

  12. 2. Conjugation • Sexual • Exchange genetic info new gene combos & bacteria diversity

  13. Endospore • Thick internal wall around DNA • Unfavorable growth conditions – heat, dry, no nutrients • Can remain dormant – years

  14. Ecological Importance • Producers • Decomposers – recycle nutrients • Nitrogen fixers – ex. Soybeans • Sewage treatment

  15. Human Importance • Foods: Swiss cheese, pickles, yogurt • Medicines: antibiotics • Crops: nitrogen fixation, control pests • Digestion: E.coli

  16. Antibiotics • Kill bacteria by interfering w/metabolism • Ex: penicillin, streptomycin, tetracycline, amoxicillin, zithromax, omnicef Staphylococcus aureus & penicillium mold

  17. How do bacteria make people sick? • 1. Produce toxins that “poison” host cells • 2. Bacterial cells crowd out healthy host cells.

  18. Griffith’s Transformation Experiment • Pneumonia bacteria experiments • 1928 – Fredrick Griffith • Had isolated 2 strains of bacteria • Smooth colonies – caused disease • Rough-edges colonies – no disease

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  23. Summary of Griffith’s Transformation Mixing Rcells + heat-killed Scells causes a factor to transform the Rcells into Scells

  24. Oswald Avery - 1944 • Extracted “juice” from heat-killed S bacteria + enzymes to destroy proteins, lipids, carbs, & RNA  transformation still occurred • Extract + enzymes to destroy above & DNA  NO transformation • DNA = Factor causing transformation

  25. Diseases • Louis Pasteur • Few kinds release toxins or damage cells • Ex: tuberculosis, botulism, strep throat & scarlet fever, tetanus, pneumonia, anthrax, meningitis

  26. Controlling Bacteria • Vaccines • Antibiotics • Sterilization • Disinfectants, • Food Processing & Storage

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