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Microbiology. Chapters we will cover: Chapter 16 → 16.7 – 16.16 Chapter 10 → 10.17 – 10.23 Chapter 24 → 24.4. Bacteria and Viruses. Introduction to Prokaryotes. Extremely small Found EVERYWHERE there is life

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  1. Microbiology • Chapters we will cover: • Chapter 16 → • 16.7 – 16.16 • Chapter 10 → • 10.17 – 10.23 • Chapter 24 → • 24.4 Bacteria and Viruses

  2. Introduction to Prokaryotes • Extremely small • Found EVERYWHERE there is life • Can live in extreme environments (salty, hot, cold, acidic environments, etc.) • Harmful (diseases) and helpful (antibiotics) • Would not be able to survive without them • - Decomposers • - Recycle nutrients • Very diverse

  3. Louis Pasteur • Considered father of microbiology • Discovered process of pasteurization • Germ Theory→ said that disease was spread by germs and tried to improve hospitals by raising standards

  4. Do NOT copy, just read: “Louis Pasteur's main contributions to microbiology and medicine were; instituting changes in hospital/medical practices to minimize the spread of disease by microbes or germs, discovering that weak forms of disease could be used as an immunization against stronger forms and that rabies was transmitted by viruses too small to be seen under the microscopes of the time, introducing the medical world to the concept of viruses.”

  5. Division of Prokaryotes • There are two main groups of prokaryotes: • Bacteria • Archaea

  6. Structure of Prokaryotes • Single-celled • Cell membrane • Most have a cell wall; made of peptidoglycan • Polymer of sugars cross linked by peptides  found only in bacteria • Cell wall is covered by a capsule • Sticky layer of proteins or polysaccharides that helps with attachment (stick to substrate) • Pili→ hair-like appendages that help with attachment / “stick” • Ex: Sex pili (more later)

  7. Internal structure • Nucleoid region→ DNA; organized in a circular chromosome • Plasmid→ a small ring of DNA separate from the chromosome  carry extra genes & can be transferred to other bacteria • Ex: Antibiotic Resistance • Ribosomes • No mitochondria or • chloroplasts, but have • infoldings of membranes so that • they can carry out respiration and • some can do photosynthesis

  8. Prokaryote Shape Spirochete  • Three general shapes: • Cocci (spherical) • Bacilli (rod shaped) • Spirilla or spirochetes (curved or spiral) • Staphlo – clusters • Strepto – chains Cocci  Bacilli So, streptococcous would look like…?

  9. Prokaryotic Movement • Use flagella • Different in structure than eukaryotic flagella • Notmade up of microtubules  naked protein structure • Doesn’t make a wave movement, it makes propeller-like rotations

  10. Oxygen Needs • Obligate aerobes→ must be in oxygen • Obligate anaerobes → cannot be in oxygen (will die if exposed to O2) • Facultative anaerobes→ can survive with or without oxygen Peptostreptococcos (anaerobe)

  11. Prokaryotic Reproduction • Asexual Reproduction = binary fission • Creates two identical cells • Can reproduce quickly in favorable conditions • Usually about 1-3 hours, some up to every 20 minutes  Ex: E. coli • Will continue until cell exhausts nutrient supply

  12. Sexual Reproduction • Increases diversity • 3 ways: • Transformation→ take up foreign DNA from surrounding environment • Transduction→ transfer of bacteria cells by a phage * phage = virus that infects bacteria 3. Conjugation→ when 2 bacterial cells mate; DNA is exchanged through sex pili

  13. Transformation Transduction Conjugation

  14. Endospores • Endospore→ • self preservation structure • thick-coated, protective cell produced inside a bacteria during harsh conditions • dehydrates and becomes dormant • Can survive all types of trauma and can last for hundreds of years • When conditions improve, shell disintegrates and it absorbs water &resumes growth

  15. Prokaryotic Nourishment • “Modes of Nutrition” • How organisms get two major resources: • Carbon • Energy (sun) • Autotrophs = producer \ self-feeder • Heterotrophs = consumers

  16. Archaea Groupings • Extreme halophiles→ • Salt lovers • Ex: Found in the Great Salt Lake • Extreme thermophiles→ • “Heat lovers” • Thrive in high temps or very acidic environments • Methanogens→ • Live in anaerobic environments • Give off methane as waste product • Abundant in digestive systems • Help break down cellulose

  17. Gram Staining • Another method of grouping bacteria via cell walls • Gram positive bacteria→ • Simpler cell walls with a thicker layer of peptidoglycan • Gram negative bacteria → • More complex cell walls; less peptidoglycan with an outer membrane that contains lipids bonded to carbs • Usually more threatening than gram+ because lipids are often toxic

  18. Helpful Bacteria • More common than the harmful are the helpful bacteria! • Important in nutrient cyclingand decomposition • Help with nitrogen fixing • Bioremediation→ use of organisms to remove pollutants from air, soil, and water

  19. Harmful Bacteria • Pathogenic bacteria cause about half of all human diseases • Exotoxins→ a poison secreted by bacterial cells; can cause deadly diseases like botulism • Endotoxins → components of outer membrane of gram negative bacteria; not deadly; ex. Food poisoning

  20. Protection against bacterial diseases • Advances in sanitation have minimized occurrences of bacterial diseases • Antibiotics = substance that kills or slows down the growth of bacteria; help cure diseases caused by bacteria Necrotizing Fascititis- destruction of fascia (connective tissue covering of muscle); caused by in invasive group of beta-hemolytic streptococci; can cause severe and rapid tissue destruction • EducationEx. Lyme disease

  21. Antibiotic Resistance Some bacteria contain plasmids that make them resistant to antibiotics. These bacteria survive when exposed to the antibiotic, and then replicate. Therefore the population becomes full of the antibiotic-resistant strain, and then we have no way to fight it! This is becoming a problem because of the excessive use of antibiotics.

  22. Bacteria as Biological Weapons • October 2001 → endospores of Bacillus anthracisfound in postal service (causes anthrax) • Middle Ages, bacterium Yersiniapestis causes the Bubonic Plague in Europe • Many countries have agreed to stop producing biological weapons, however, how many countries are holding up that pact is unknown

  23. Viruses

  24. Viral Structure • Considered “genes in a box” • All viruses are made up of two things: • Nucleic Acid (DNA OR RNA) –NEVER both • Capsid (Protein coat) Bacteriophage – a virus that infects bacteria

  25. Virus Facts • A parasite that can ONLY reproduce inside living cells (called host cells) • They use the materials of the host cell to make their components for them • Virus reproduction → • Lytic Cycle • Lysogenic Cycle Note: Viruses are NOT cells…they are not prokaryotes or eukaryotes

  26. Lytic Cycle • Called “virulent” viruses (infective, poisonous) • Kill host cell right away • Cell bursts –“lysis” • Releases the viruses that are produced within the cell • See picture and understand process

  27. Lysogenic Cycle • Called “temperate” viruses • Does not kill host cell right away • Stays dormant in host cell DNA until outside stressor (sunlight, stress, poor immune system) causes the virus to “activate” and come out • DNA is incorporated into bacterial cell’s DNA = now called a prophage

  28. Lysogenic Cycle

  29. Disease Causing Viruses - Animals • Viruses cause many diseases • RNA viruses→ influenza (flu!), measles, mumps, AIDS, polio • DNA viruses→ hepatitis, chicken pox, herpes • If a virus attacks a cell that doesn’t divide (Ex: nerve cells with polio), it can cripple you for life • Hard to create antiviral drugs, because it is hard to kill the virus without killing the host cell • Antibiotics do NOT work on viruses!

  30. Retroviruses • Type of RNA virus • Contains an enzyme called reverse transcriptase which does reverse transcription→ makes DNA from RNA • Retro means “backwards” • Example: • HIV, AIDS R.T. Enzyme

  31. Disease Causing Viruses - Plants • Viruses can also attack plants and destroy entire fields of crops • Ex: Tobacco Mosaic Virus • Injured plants are more susceptible to virus attacks because it is easier to get past the cell wall • Pass onto offspring • Genetically engineering plants that are resistant to viruses

  32. Emergence of Viruses • Threeprocesses contribute to the emergenceof viral diseases: • Mutations (i.e. - flu) • Contact between species (i.e. - bird flu) • Spread from isolated populations (AIDS)

  33. Immune Response • Immune system recognizes and defends against invading microbes • General response and then a more specific response • Acquired Immunity→ develops after exposure to pathogen • Antigen → foreign molecule that brings on an immune response • Ex: Surfaces of viruses, mold, bacteria, dust, pollen, pet dander, etc.

  34. Antibodies • Antibody→ • Produced in response to antigen exposure • Protein found in blood • Attaches to the antigen to counter its’ effects  protect body against the antigens • Specific! • Immune system has a great “memory” → • Once exposed, your immune system will react more quickly the next time around (i.e. – chix pox)

  35. Vaccines • Vaccination (immunization) → • Body is introduced to a weakened version of a disease causing microbe • Body makes antibodies so that if it is exposed, it will be ready to fight it off • Widespread vaccinations • Polio, mumps, measles, and smallpox • Can be used for viral (flu) ORbacterial (typhoid) diseases • Viruses can be PREVENTED using vaccines • Ex: Gardasil– HPV

  36. Sections Covered • Chapter 16 → • 16.7 – 16.16 • Chapter 10 → • 10.17 – 10.23 • Chapter 24 → • 24.4

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