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Microbiology

Microbiology. Viruses and Bacteria. History of Microbiology. Edward Jenner (1798): 1 st Vaccine Joseph Lister (1867): Aseptic Surgery Luis Pasteur (1857-1864) Fermentation Pasteurization Biogenesis Robert Koch Germ Theory of Disease (1876) Microorganism can cause disease

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Microbiology

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  1. Microbiology Viruses and Bacteria

  2. History of Microbiology Edward Jenner (1798): 1st Vaccine Joseph Lister (1867): Aseptic Surgery Luis Pasteur (1857-1864) • Fermentation • Pasteurization • Biogenesis Robert Koch • Germ Theory of Disease (1876) • Microorganism can cause disease • Koch’s Postulates • Pure Cultures (1881) • Tuberculosis (1882) Alexander Flemming (1928): Penicillin Jonas Salk (1955): Polio Vaccine

  3. Koch’s Postulates

  4. Viruses • Virus: A parasitic non-living entity! • Must exist within a “host” • No Cellular Structure • No cytoplasm, organelles, or phospholipid membranes • Capsid: Outer coat made of protein • Core: Central region made of nucleic acid • DNA or RNA • Envelope: Made of lipids, carbo, and proteins • Spikes: Used for attachment • Carbohydrate and protein (glycoprotein)

  5. Viruses

  6. Virus Structure

  7. Rod-shaped:(helical) Tobacco mosiac virus (TMV) Spherical:(round or oval) HIV or Aids virus Polyhedral: (many sides) Polio virus Bacteriophage Infects bacterial cells Virus Shapes

  8. A virus that infects a bacterial cell Used to study viral behavior T-4 bacteriophage is commonly studied! Bacteriophage

  9. The Lytic Cycle 1. Attachment Adsorption 2. Entry 3. Biosynthesis • Replication • Transcription • Assembly • Formation 4. Lysis and release • The cell explodes

  10. Lysogenic Cycle 1. Attachment 2. Entry 3. Integration 4. Cell division Replication 5. Lysis? • Provirus:A virus that becomes integrated into the host cells DNA

  11. DNA Virus Lytic cycle Attachment/Adsorption Entry Biosynthesis Lysis and release Lysogenic Cycle Attachment Entry Integration Cell division and possible lysis RNA Virus Lytic Cycle Similar to DNA viruses Viral RNA can serve as mRNA to construct proteins! Lysogenic Cycle Retrovirus: A virus that can transcribe DNA from RNA (provirus) Reverse transcriptase: An enzyme that can reverse normal transcription (reverse transcription)!! HIV is an example Viruses can contain DNA or RNA

  12. DNAmakes RNAmakes Protein A retrovirus can reverse this sequence The virus enters as RNA and then can manufacture DNA. It will integrate into the host cells DNA HIV replicates 1010 times per day It takes 6 weeks for HIV to become resistance to AZT (one of the most common drugs to treat HIV) HIV treatment options Triple drug therapy is a must! 1. Integrase inhibitors 2. Reverse transcriptase inhibitors 3. Protease inhibitors HIV

  13. Bacteria: Living!!Kingdom ArchaebacteriaKingdom Eubacteria Structure • Prokaryotic: Nucleoid region with a loop of chromosomal DNA • Cell wall (peptidoglycan) • Capsule: (outer protective coat found on some bacteria) • Flagella: One…or many • Endospore: Protective wall that surrounds some bacteria. Allows bacteria to remain dormant for long periods

  14. Flagella: Swimming movement • Protein • Pili: Sex pilus Mediates DNA transfer during conjugation • Protein • Common pili or fimbriae: Attachment to surfaces; protection against phagotrophic engulfment • Protein  • Capsules:(includes "slime layers" and glycocalyx) • Attachment to surfaces; protection against phagocytic engulfment, occasionally killing or digestion; reserve of nutrients or protection against desiccation • Usually polysaccharide; occasionally polypeptide • Cell wall: • Gram-positive bacteria Prevents osmotic lysis of cell protoplast and confers rigidity and shape on cells Peptidoglycan (murein) complexed with teichoic acids • Gram-negative bacteriaPeptidoglycan prevents osmotic lysis and confers rigidity and shape; outer membrane is permeability barrier; associated LPS and proteins have various functions Peptidoglycan (murein) surrounded by phospholipid protein-lipopolysaccharide "outer membrane“ • Plasma membrane:Permeability barrier; transport of solutes; energy generation; location of numerous enzyme systems Phospholipid and protein • Ribosomes: Sites of translation (protein synthesis)RNA and protein • Inclusions: Often storage reserves of nutrients; additional specialized functions • Highly variable; carbohydrate, lipid, protein or inorganic • Chromosome:Genetic material of cell DNA • Plasmid:Extrachromosomal genetic material DNA

  15. Bacterial Reproduction Binary Fission: A form of asexual reproduction where the cell splits into two. (DNA must replicate first) Plasmid Sharing: The process where bacterial cells exchange plasmid DNA using pili. (Linked to antibiotic resistance) Conjugation: Exchange of “nucleoid” or chromosomal DNA

  16. Plasmid Sharing and Binary Fission

  17. Bacterial Cell Shape • Bacillus:Rod-shaped • Spirilla:Spirals • Cocci:Round or spherical • Strept:Chains • Staph:Clusters • Diplo:Two together

  18. Bacterial Shapes

  19. Bacterial Shapes

  20. Heterotrophic:Obtain energy from organic matter. Parasitic: (+, -) Saprophytic: Live off of dead or decaying matter (chemo-heterotroph) Autotrophic: Can make their own nutrients Photoautotroph: Use sunlight for energy CO2 for carbon Early blue green bacteria/cyanobacteria Produced oxygen for early earth’s atmosphere Chemoautotroph: Use inorganic compounds for energy Use CO2 for carbon Found in hydrothermal vents Thrive on hydrogen sulfide Nutrition

  21. Methanogens:Produce methane Swamps, marshes, digestive tracts of mammals. Breakdown decaying matter Halophiles: “salt loving” Great salt lake, dead sea Acidophiles:Thrive in acidic environments Thermophile:Thrive at high temps Acidophiles and thermophiles are found in yellowstone springs, hydrothermal vents. Ph is often as low as 2. Lack peptidoglycan cell walls Membrane lipids are different from Eubacteria DNA sequences of many archaebacteria genes are more similar to eukaryotes than to Eubacteria Ancient Bacteria(Archaebacteria)

  22. Hydrothermal VentsGiant Tube worms

  23. A differential stain used to separate bacteria into two groups Based on cell wall differences Bacteria are separated into: Gram + Gram - Steps 1. Smear air dry, heat fix 2. One minute Crystal Violet RBD 3. One minute Gram’s Iodine RBD 4. Decolorize with ETOH(drops) RBD 5. 30 sec. Safranin RBD, AD The Gram Stain Procedure

  24. Gram (+) & Gram (-)

  25. Kirby Bauer Test of antibiotic effectiveness

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