microbiology week 2

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torrespeterytania
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microbiology week 2
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2012-12-06 00:57:10
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micro week 2 saturday
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  1. A classification system based on collecting individuals into groups and groups into progressively more inclusive and broader groups is called a 
    hierarchical scheme of classification
  2. hierarchical scheme of classification
    A classification system based on collecting individuals into groups and groups into progressively more inclusive and broader groups
  3. Taxonomy
    • The branch of biology that names and classifies species
    • The science of classifying organisms
  4. It formalizes the hierarchical ordering of organisms
    Taxonomy
  5. Name the following classification
    1.)  establishes the criteria for identifying
    organisms
    2.) it arranges related organisms into groups
    based on shared characteristics
     3.) it provides important information on how
    organisms evolved
    Classification of organisms
  6. A basic principle of taxonomy is that members of higher-level groups share            characteristics than those in lower-level groups.
    Fewer
  7. Who devised the taxonomic scheme that is both practical and adaptable to expanding information
    Swedish biologist names Carolus Linnaeus
  8. The Linnaean scheme remains the basis for biological
    classification today in 2 regards: 
    •   1.)  we continue to group organisms hierarchically
    •   2.)  we use his nomenclature.
  9. •Linnaeus introduced a binomial nomenclature (each organism is designated by 2 names).
    • •The first name is the organism’s genus designation & the second is its specific epithet. 
    • •Together, the 2 constitute the species name. 
  10. What is a Species:
    •Groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups. 
  11. At the highest level, life is classified into three domain
    • 1. Bacteria (modern bacteria)
    • 2. Archaea (accient bacteria)dna and anatomy resemble more to eukarya 
    • 3. Eukarya
  12. •Archaea  (Ancient Bacteria)
    prokaryotes living in extreme habitats
  13. •Bacteria (Modern Bacteria)
    eubacteria
  14. Eukarya
    • Protozoans
    • Fungi
    • Plants
    • Animals
  15. •Domain Bacteria and domain Archaea consist of ?
    Prokaryotes
  16. Domain Eukarya, the eukaryotes Includes 
    various protist kingdoms and the kingdoms Plantae, Fungi, and Animalia
  17. Many of the prokaryotes known as archaea live in Earth‘s 
    extreme environments, such as salty lakes and boiling hot springs
  18. Kindom Animalia consists of 
    multicellular eukaryotes that ingest other organisms
  19. Kingdom Plantae consists of
    multicellula eukaryotes that carry out photosynthesis, the conversion of light energy to food
  20. Binomial nomenclature
    The first part of the name identifies the genus to which the species belongs; the second part identifies the species within the genus. For example, humans belong to the genus Homo and within this genus to the species Homo sapiens.
  21. •Characteristics of bacteria
    • Dormancy
    • Toxins
    • Obligate parasites
    • Antibiotics
  22. Archaebacteria
    • Found in harsh enviroment
    • Undersea volcanic vents, acidic hot springs, salty water
    • None are pathogenic to human
  23. Eubacteria:
    • Called the true bacteria 
    • Most bacteria are in this group 
    • Include photosynthetic Cyanobacteria
  24. Bacterial Structure
    • No nucleus or membrane-bound organelles
    • Contain ribosomes
    • Single, circular chromosome in nucleoid region
  25. Bacillus Shape
    Rod Shape 
  26. Coccus Shape
    Spherical (Round) shape
  27. Vibrio shape
    Comma shaped with flageka
  28. Spirillum Shape
    Spiral Shape
  29. Spirochete 
    Wormlike spiral Shape
  30. Grouping of Bacteria
    Diplo - 
    Strepto - 
    Staphylo - 
    • Diplo - Groups of two 
    • Strepto - chains
    • Staphylo - Grapelike structers
  31. What gives bacteria a advantage to live in exttreme conditions
    Dormancy 
  32. How do bacteria (gram +) become DORMANT
    By forming an endospore
  33. Decribe bacterial  dormincy
    • Survival mechanism
    • Dries Out
    • Stops all metabolic activity
    • Forms an endospore
    • Contains genetic material of the vegetative cell
  34. Describe Vegetative Cells
    • Take in nutrients 
    • Convert nutrients into energy and biomass 
    • Expell waste 
    • Grow and divide
  35. What protects the DNA in dormant endospore bacteria
    Endorespore are fille SASPS (small acid soulble proteins that protect DNA)
  36. Endospore are surrounded by a tough 
    Keratin like coat
  37. Life cycle of an endospore
    • Vegetative Cell 
    • Develop spore coat
    • Becomes Mother Cell 
    • Free endospre 
  38. What endospore cause diseases
    They all cause disease
  39. Clostridium botulinum
    (type of endospore )
    • •Causes botulism (food posioning)
    • •Causes infant botulism from honey 
    • •Abundant in soil throughout the world
  40. Name the 3 type of Clostridium botulinum 
    • Type A C. botulinum—found in neutral/alkaline soil west of the Mississippi River
    • Type B C. botulinum—found in eastern part of the country 
    • Type C C. botulinum—found in wet soils (can effect fish)
  41. Botulism—found in food
    • Canning—endospores are not eradicated if the temperature is not sufficiently high
    • Honey has endospores 
    • The spores germinate and become vegetative bacteria The vegetative bacteria produce botulism toxin—a potent neurotoxin
  42. Botulism 
    • Toxin has no taste
    • Food is often not spoiled by the bacteria
    • A small amount of food with the toxin can be lethal
    • End result: Paralysis and respiratory failure
    • Treatment: antitoxin
  43. Bacterial Toxins:
    Definition 
    –Soluble substances that alter normal metabolism of host cells with deleterious effects on the host
  44. Bacterial Toxins Type
    • Exotoxin
    • Endotoxin
  45. Describe exotoxin
    protein produced by bacteria either excreted or bound to bacterial surface and released when lysed (lysed = dead bacteria)
  46. Describe Endotoxin
    • Endotoxin—LPS of the outer membrane of Gram— bacteria ( only release if bacteria dyes if antibiotics are taken makes it worse due to killing of bacteria
    • •Acts as toxin only under special circumstances
  47. Toxin Production –Found on phage; toxin genes for:
    • Diphtheria
    • Botulism
    • Scarlet fever
    • Toxic streptococci (“flesh-eating”)
  48. Toxin Production–Found on plasmids:
    • E. coli toxin causes diarrhea
    • S. aureus toxin causes “scalded skin syndrome”
  49. Sporulating bacteria sometimes release toxins during spore formation
    •Bacterial cells eventually lyse and liberate cytoplasmic
    proteins, including toxins
    Examples:
    • –Examples:
    • organisms that cause botulism
    • gas gangrene
    • tetanus
  50. Level of toxicity
    • 1 g tetanus, botulinus, or Shiga (type of ecoli) toxin is
    • enough to kill 10 million people
    • 100-fold more is required for diptheria
    • 1000-fold more for Pseudomonas A
  51. Bacterial Endotoxins 
    • –Misleading name
    • •Toxin is located on outside of microorganisms
    • –LPS of gram – bacteria
    • –Lipoteichoic acid or gram + bacteria
    • •Only toxic at high levels 
  52. Endotoxins bind to 
    host immune cells and disable them
  53. Enzymes secreted by bacterial cells into the extra cellular
    matrix of host
    • –Membrane Damaging Toxins
    • –Enzymes which act in the extra cellular matrix
    • –Enzymes which subvert drug therapy in patients
  54. –Membrane Damaging Toxins
    • Enzyme destruction of host cell membranes
    • Lyse red blood cells 
    • Membrane pore forming complex
  55. –Enzymes which act in the extra cellular matrix
    • Spreading factors
    • Breaks down connective tissue
    • Attacks blood clots 
    • Thins pus filled with DNA
  56. –Enzymes which subvert drug therapy in patients
    Penicillinase
  57. Some Common Exoenzymes
    • α toxin 
    • Hemolysins
    • Streptokinase 
    • Hyaluronidase
    • DNasel
  58. Toxins are soluble substances that 
    alter normal metabolism of host cells with deleterious effects on the host
  59. •E-coli isn’t usually disease- causing however, some cause 
    gastrointestinal and urinary tract infections 
  60. E. coli can produce shiga toxin most potent toxins
    known to man
    Causes 
    bloody diarrhea, which, in 2 to 7% of cases, lead to hemolytic-uremic syndrome 
  61. Staphylococci
    • Gram-positive
    • Lack spores and flagella
    • Common inhabitant of the skin and mucous membranes
    • Frequently involved in nosocomial and opportunistic
    • infections
    • Can cause wound infections by penetrating through broken skin
  62. Toxins of S. aureus
    Exotoxins
    • Hemolysins (α, β, γ, δ)
    • Leukocidin 
    • Enterotoxin 
    • Exfoliative toxin 
    • Toxic shock syndrome toxin (TSST)
  63. S. aureus Exotoxins:
    Hemolysins (α, β, γ, δ) 
    lyse red blood cells
  64. S. aureus Exotoxins:
    Toxic shock syndrome toxin (TSST)
    lyses neutrophils and macrophages
  65. S. aureus Exotoxins:
    Enterotoxin
    induce gastrointestinal distress
  66. S. aureus Exotoxins:
    Hemolysins (α, β, γ, δ) 
    separates the epidermis from the dermis
  67. S. aureus Exotoxins:
    Toxic shock syndrome toxin (TSST)
    induces fever, vomiting, shock, systemic organ damage
  68. Vibrio cholerae
    • •Vibrio cholera
    • –Produces exotoxin
    • –Gram negative vibrio
    • –Unusual disease 
    • •Cholerae does not invade tissue
    • •Cholerae does not damage tissue
    • –Humans are incidentally infected when ingesting contaminated food or water
  69. •Bacillus anthracis
    • –Produces exotoxin
    • –Gram positive spore forming bacteria
    • –Found in soil
    • –Anthrax disease – direct exposure to spores
    • •Inhalation – pulmonary
    • •Ingestion – gastrointestinal
    • •Invasion into surface wound – cutaneous
    • –No cases involve person to person spread
  70. Mycobacterium tuberculosis
    • More than one-third of the world population is infected.
    • The organism has caused more human deaths than any other bacterium in the history of mankind. 
    • Its unusual cell wall, rich in lipids (mycolic acid is a lipid instead of peptidoglycan), is a key virulence factor (like in TB) 
    • Unusual cell wall allows the bacteria to hide from host immune cells
  71. Rickettsias
    • •Obligate intracellular parasites.
    • •(bacteria) Transmitted to humans by insects and ticks
    • •Grow and reproduce only within the cells of other organisms. 
    • –Genus Ehrlichiae:  Live in white blood cells.
    • –Genus Rickettsia:  Cause spotted group fevers (Rocky mountain spotted fever, endemic typhus).
  72. The discovery of the first antibiotic was an accident
    • –Alexander Fleming accidentally contaminated a plate with a fungus.
    • –He observed a clearly defined region of no bacterial growth where the fungi had contaminated the plate. 
    • –The area around the fungus was eventually referred to as a zone of inhibition.
  73. Antibiotics are made by
    • Fungi
    • Bacteria
  74. Spectra
    • The original natural molecules used by humans as antibiotics have a very narrowspectrum.
    • Penicillin activity is restricted to Gram-positive bacteria.
    • Natural molecules can be chemically modified making it possible to broaden their spectrum.
    • Antibiotics are classified as either broad-spectrum or narrow-spectrum.
  75. •Antibiotic targets can be subdivided into five major groups:
    • –The bacterial cell wall
    • –The bacterial plasma membrane 
    • –Synthesis of bacterial proteins 
    • –Bacterial nucleic acids 
    • –Bacterial metabolism(stop metabolic activity)
  76. One of the most important bacterial defense mechanisms is the production of 
    • enzyme β-lactamase.
    • are resistant to penicillin.
  77. S. aureus is one of the leading causes of hospital-based 
    bloodstream infections with a crude mortality rate ~25%.
  78. MRSA can cause 
    pneumonia and infections in the blood, bones and urine
  79. E-test
    • –Permits determination of the minimal inhibitory
    • concentration (MIC).
    • •The lowest antibiotic concentration that prevents growth
    • –Uses plastic-coated strips containing gradients of
    • antibiotic concentrations.
    • After incubation MIC can be read from the scale
  80. Kirby-Bauer Test
    • •An agar plate is covered with known pathogen.
    • •Filter-paper disks impregnated with known concentrations of the compound.
    • –They are placed on agar
    • .–Zones of inhibition can be identified.

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