Microbiology Lecture 1&2

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hoyadavis
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37584
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Microbiology Lecture 1&2
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2010-09-27 23:11:44
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test history microbes bacteria
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Lecture 1 and 2 in prep for test 1.
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  1. Why is microbiology important?
    • Microbes cause disease
    • can affect food supply
    • can be beneficial for digestion, protection, bio-remediation and food procession
  2. Characteristics of bacteria
    • unicellular, prokaryotic
    • no nuclear membrane, mitochondria, Golgi or ER
    • reproduce asexually
    • many can be beneficial
  3. Characteristics of Viruses
    • cause many of the biggest public health threats
    • smallest infectious particle
    • contain DNA or RNA housed inside a protein coat
    • require host cell for replication
    • can infect animals, plants and other microbes
  4. Characteristics of fungi
    • eukaryotic
    • contain nucleus, golgi, mitochondria and ER
    • can be unicellular (reproduce asexually) or multicellular (asexual or sexual)
  5. Characteristics of Parasites
    • most complex microbes
    • eukaryotic
    • infections are often chronic
  6. Name the smallest type of microbe
    viruses
  7. which microbes are eukaryotic? which are prokaryotic?
    • Eukaryotic
    • fungi & parasites
    • Prokaryotic
    • bacteria
  8. Name the 5 methods of transmission
    • inhalation
    • ingestion
    • direct contact
    • indirect contact
    • animal vectored
  9. Method of Transmission: Inhalation
    • transmitted by infectious droplets from cough, sneeze, etc.
    • eg. Flu, TB, common cold
  10. Method of Transmission: Ingestion
    • germs get on your hands and then on food or skin
    • can occur from unwashed produce and contaminated meat
    • eg. salmonella, e. coli
  11. Method of transmission: direct contact
    • spread directly from one person to another
    • eg. HIV, gonnorhea
  12. Method of transmission: indirect contact
    • disease is spread via fomites (inanimate objects harboring germs)
    • eg. tissues, door knobs, toilets, phones
  13. Method of Transmission: Animal Vectored
    • transmission through insect bite
    • eg. Malaria, Lyme disease
  14. Influential ideas in Microbiology:

    Hooke- 1664
    coined the term "cells". uses microscope to describe mold
  15. Influential ideas in Microbiology:

    van Leewenhoek- 1674
    first describes bacteria in detail
  16. Influential ideas in Microbiology:

    Redi- 1668
    hypothesizes against spontaneous generation of maggots on meat
  17. Influential ideas in Microbiology:

    Spallanzani- 1768
    shows that if air is removed form flask, no bacteria grows
  18. Influential ideas in Microbiology:

    Jenner- 1788
    father of vaccines. discovers a cure for small pox
  19. Influential ideas in Microbiology:

    Semmelweis- 1840
    introduced antiseptic practice to medicine
  20. Influential ideas in Microbiology:

    Henle- 1800s...
    formally described germ theory
  21. Influential ideas in Microbiology:

    Koch- 1800s...
    • developed methods for pure culture and aseptic technique.
    • Kochs postulate
  22. Influential ideas in Microbiology:

    Gram 1800s...
    develops methods for pure culture and aseptic technique
  23. Influential ideas in Microbiology:

    Fleming- 1928
    discovered first antibiotic (penicillin)
  24. Spontaneous generation
    • belief in spontaneous creation of life from organic matter.
    • Redi, Spallanzani, and Pasteur contributed to the debunking of that myth
  25. Describe germ theory
    proposal that diseases are caused by microorganisms. contagions are organic and living.
  26. Koch's postulate
    • the bacteria must be present in every case of the disease
    • the bacteria must be isolated from the host with disease and grown in pure culture
    • the specific disease must be reproduced when pure culture is inoculated into a healthy susceptible host
    • the bacteria must be recoverable from experimentally infected host

    • n/a if particular bacteria cannot be "grown in pure culture"
    • if no animal model of infection with a particular.
  27. Name four categories for classifying bacteria
    • appearance
    • growth and metabolism
    • antigenicity
    • genotype
  28. Appearances of a bacterium
    can either be macroscopic (colony morphology) or micro (cell morphology)
  29. Descriptive terms of colony vs cell morphology
    • colony: form, elevation, margin, color, smell and mucoid/dry
    • cell: shape, arrangement and gram stain
  30. Description of growth and metabolism of bacteria
    • antibiotic resistance
    • sugar fermentation
    • oxygen requirement
    • production of metabolic products and enzymes
  31. What is a key method for using antigenicity
    serotyping: when antibodies detect antigen on bacterial surfaces
  32. What method of classification can be used for growing organisms that are difficult/dangerous to grow
    antigenicity
  33. Describe classification by genotype
    • detection of specific DNA sequences (PCR)
    • does not require living growing bacteria
    • used for rapid detection of slow-growing organisms
    • can be used to identify organisms that cannot be cultured
  34. What is PCR
    • polymerase chain reaction.
    • method for amplifying DNA
    • generates large quantities of DNA from small amounts of starting material
  35. Steps of PCR
    • denaturation
    • annealing
    • extension
  36. Gel Electrophoresis
    • Sorts DNA based on size and change
    • DNA naturally carries a negative charge
  37. Function of bacterial cell envelope
    • protects the cell against chemical and biological threats (antibiotics, dessication)
    • makes surface colonization possible
    • provides shape and structure to cell
  38. Capsule/slime layer (glycocalyx)
    • found in almost all bacteria
    • unnecessary for growth
    • impedes ingestion by immune cell
    • barrier to toxic hydrophobic molecules
    • promotes adherence to other bacteria or host tissue (virulence factor)
  39. Flagella
    provide motility and are anchored in bacterial membrane
  40. chemotaxis
    swim and tumble movement
  41. Fimbrae
    • hairlike structures
    • promote adherence to other bacteria or host cells
    • virulence factor for many bacteria
  42. Gm+ cell envelope
    • have thick peptidoglycan layer close to exterior surface.
    • have only one cellular membrane
    • can contain teichoic and lipoteichoic acids
    • Shed teichoic and lipoteichoic acidsin host and invoke eimmune response
    • promote adherence to other bacteria
  43. Gm- cell envelope
    • have 2 cell membrane layers (outer and inner) after the cytoplasmic membrane
    • has a thin peptidoglycan layer
    • has no teichoic or lipoteichoic acids
    • outer membrane contains LPS
  44. Antibiotic treatments effective agains Gm+ bacteria attack what part of the cell? Give an example of a treatment.
    • Gm+ antibiotic treatments attack the cell wall.
    • Eg. vancomycin and bacitracin
  45. Antibiotic treatments effective against Gm- bacteria attack what part of the cell? Give an example of a treatment
    • Gm- antibiotics bind to the lipid A portion of LPS in order to weaken the cell
    • Eg. Polymyxin B
  46. Functions of the outer membrane of a cell
    • serves as a permeability barrier to large foreign objects
    • provides protection from the environment
    • contains the endo-toxin Lipopolysaccharide (LPS)
  47. Lipopolysaccharide (LPS)
    • induces fever and shock
    • found in Gm- outer membrane
  48. Parts of LPS
    • Lipid A
    • core polysaccharides
    • O antigen
  49. Lipid A
    • essential for bacteria viability
    • responsible for endotoxing activity
    • conserved
  50. Core polysaccharides
    • 9-12 sugars essentials for LPS structure
    • moderately variable
  51. O antigen
    • polysaccharide side chains
    • highly variable
  52. Peptidoglycan layer
    • provides rigidity and shape.
    • barrier against toxic chemicals
  53. cytoplasmic membrane function
    • energy production
    • uptake of metabolites
    • release of substance
  54. plasmids
    • small extrachromosomal DNA
    • common in Gm-
    • confer selective advantage to bacterium
  55. Spores
    • produced by Gm+, but not Gm-
    • dehydrated multi-shelled protective structure
    • protects from heat, radiation, enzymes, chemicals
    • complete chromosome, but minimum proteins

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