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BACTERIA (Ch. 24) AND VIRUSES (Ch. 25)

BACTERIA (Ch. 24) AND VIRUSES (Ch. 25). BACTERIA: Simplest & most primitive life forms (fossils from 3.5 bya). 2 Kingdoms: Archaebacteria Eubacteria. Archaebacteria: “ ancient bacteria” live in extreme environments. Thermoacidophile : thrives in hot , acidic environments.

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BACTERIA (Ch. 24) AND VIRUSES (Ch. 25)

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  1. BACTERIA (Ch. 24) AND VIRUSES (Ch. 25)

  2. BACTERIA: Simplest & most primitive life forms (fossils from 3.5 bya)

  3. 2 Kingdoms: Archaebacteria Eubacteria

  4. Archaebacteria: “ancient bacteria” live in extreme environments

  5. Thermoacidophile: thrives in hot, acidic environments

  6. Halophile: thrives in salty environments

  7. Methanogen: thrives in methane-rich environment

  8. Eubacteria “true bacteria” live in “normal” environments

  9. Simple Structure: PROKARYOTE no nucleus or membrane-bound organelles

  10. Chromosome is in one loop, not in pairs Chromosome # 1

  11. Have ribosomes; needed to make structural proteins and enzymes

  12. Cell Wall: Some cell walls have a thick layer of peptidoglycan, a carbohydrate

  13. Gram Positive: stains purple; stain is held by peptididoglygan layer

  14. Gram Positive

  15. Gram Negative: Stains pink; stain resistant since there is a layer over the peptididoglycan layer

  16. Gram Negative

  17. Cell Parts:

  18. Classified by Shapes 1.Bacillus: ovals

  19. 2.Coccus: round

  20. 3.Spirillus: wavy or bent

  21. Configurations: Diplo: in pairs Diplococcus

  22. Strepto: in chains Streptococcus Streptobacillus

  23. Staphylo: in clusters

  24. Reproduction: Binary Fission

  25. Rapid life cycle since there is no mitosis

  26. Some genetic recombination by three different methods:

  27. Conjugation • Two bacteria join up at the pili (conjugation bridge) and exchange a small loop of DNA that has detached from the main DNA (plasmid)

  28. The plasmid is incor- porated into the DNA of the receiving cells conjugation bridge

  29. Transformation: • Substitutes new DNA for a similar fragment in its original DNA

  30. Transformation:

  31. Transduction: • A virus obtains a piece of DNA from host bacterium • Virus transfers DNA to new cell that it infects

  32. Transduction:

  33. NUTRITION: AUTOTROPHIC by photosynthesis or chemosynthesis

  34. Heterotrophic: many are saprophytic-- eat dead stuff

  35. METABOLISM/ RESPIRATION: Obligate Aerobe Must have Oxygen to survive

  36. Obligate Anaerobe: Can only survive in the absence of oxygen

  37. Facultative Anaerobe: Can live with or without oxygen

  38. Effects on • Humans: • Decomposers • Food & Drug • industries

  39. Clean up toxic • waste naturally • Natural • pesticides

  40. Nitrogen fixation Extract nitrogen from the environment for plants to use

  41. Cause diseases • by releasing • toxins • into host • organism

  42. Exotoxins: • Produced by Gram positive cells • Toxins constantly produced and steadily released by cell • Protein-based toxins

  43. Endotoxins: • Produced by Gram-negative cells • Toxins released when bacterium dies • Lipid or carbohydrate based toxins

  44. How can we control bacteria? • Antibiotics! Wash hands! • Good sanitation! Pasteurization • Immunizations! Safe sex!!!

  45. Problem: • ANTIBIOTIC RESISTANCE • From overuse (antibiotics only • work on gram-positive • bacteria; doctors have • prescribed for any bacteria • and also viruses • Patients don’t take all • prescribed medication, as • directed

  46. Bacterial mutations occur that also result in resistance • Example: Tuberculosis • used to respond to • penicillin but now it • doesn’t

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