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Notes: Bacteria

Notes: Bacteria. 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. Kingdom Archaebacteria. Autotrophic Found in extreme environments

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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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