Bio 11 microbiology

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Bio 11 microbiology
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2010-11-17 02:18:17
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micro organisms, viruses, bacteria
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  1. Who discovered viruses?
    Dmitri Iwanowski : Found that juice in tobacco leaves caused infections in other plants

    • Martinus Beijerinck : Realized tiny particles in juice that caused infection
    • -named particle "virus" which means infection
  2. What is the definition of Virus?
    -Non-cellular particle made of genetic material and protein that can invade living cells.
  3. Structure: components of a virus
    • 1. Core of nucleic acids (DNA, RNA)
    • 2. protein coat (capsid) that surrounds nucleic acid
    • *some have more complex structures.
  4. What is a bacteriophage?
    -Virus that infects bacteria
  5. Diversity in structure: what are the shapes of viruses?
    • a) rods
    • b) cubes
    • c) Helix
  6. Average size of virus?
    • between 10-300 nm. (nano-metres)
    • * must use scanning electron microscope or transmission electron microscope
  7. Why are viruses specific?
    -Can only infect a specific host

    ex: HIV specific to humans
  8. Are viruses living?
    Viruses are obligate intercellular parasites.

    (must feed off of host cell)
  9. Living Characteristics of viruses?
    • -genetic material
    • -replicate (reproduce)
    • -evolve (mutate)
  10. Non-living characteristics of viruses?
    • -non-cellular
    • -requires host
    • -doesn't use energy
  11. What are viral infections?
    -Causes infections by injecting DNA into host
  12. What are the 4 general phases of viral infection?
    • 1. infection
    • 2. growth
    • 3. replication
    • 4. Lysis
  13. What are the two different ways viruses can infect cells?
    • 1. Lytic infection
    • 2. Lysogenic infection
  14. What is the main difference between Lytic and Lysogenic infection?
    • - Growth phase of Lysogenic infection:
    • *Viral DNA is incorporated into host DNA (prophage)
    • -remains dormant for a long period of time
    • -cell replicates viral DNA by binary fission
  15. What happens during infection phase ?
    • -virus attaches to host cell using tail fibres
    • -inserts DNA into cell
  16. What happens during the growth phase of Lytic infection?
    • -Host's RNA polymerase (enzyme) make MRNA from viral DNA
    • -MRNA takes over host cell
  17. What happens during the replication phase?
    -virus uses host's machinery (ribosomes, golgi apparatus etc) to construct :

    • 1) DNA
    • 2) Capsids (protein)
  18. What happens during the lysis phase?
    • -Host cell becomes filled with new viruses....then bursts (lyse)
    • - Spreads viruses to neighbouring cells.
  19. How long can a Lytic infection occur in?
    25 mins
  20. What is the origin of viruses?
    • -evolved after first living cell (because must live inside host)
    • - evolved from genetic material of living cells, mutated and evolved
  21. What are the advantages of viruses?
    • - genetic research (cancer)
    • - Gene therapy
    • - genetic engineering (injecting specific DNA)
  22. What are the disadvantages of viruses?
    1. Disease (HIV, Influenza) viruses are pathogens

    • 2. Cancer
    • - during infection when DNA is inserted, gene may become an oncogene causing cancer
    • -cell undergoes uncontrolled divisions forming tumor (benign or malignant)
  23. How can you prevent viral infections?
    • 1. good hygiene
    • 2. Healthy lifestyle (diet, exercise)
  24. What are the two lines of defence against viruses?
    1. Non-specific defences

    2. Specific defenses
  25. What are the non specific defences and what do they do?
    • - skin (oil and sweat provide acidic environment)
    • -cilia/mucus (traps virus)
    • -secretions (destroys virus)
    • -phagocytes (engulf bact/viruses -> leads to fever)
    • -interferon (infected cell produces protein that interferes with virus & slows it)
  26. What are the specific defences against viral infection?
    • 1. Antibodies/immune response
    • 2. Immunity
    • 3. Cell mediated immunity
  27. How do antibodies/immune response defend against viral infection?
    Pathogen specific antibodies are produced that bind to and inactivate virus (antigen)
  28. How does immunity defend against viral infection?
    • i) active : injection of vaccine that causes body to produce antibodies
    • ii) passive: injection of antibodies produced in another animal
  29. How does cell mediated immunity defend against viral infection?
    Killer T-cells attack antigen-bearing cells and destroy them
  30. What are the main differences between prokaryotic and eukaryotic cells?
    Prokaryotic cells do not have a nucleus, or membrane.
  31. How are monerans classified?
    • -all monerans are prokaryotic
    • - All called bacteria
    • - Divided into 4 phyla
  32. What are the 4 phyla that monerans are divided into?
    • -eubacteria
    • -cyanobacteria
    • - archaebacteria
    • -prochlorobacteria
  33. What are the characteristics of Eubacteria?
    • - surrounded by cell wall composed of complex carbs
    • - within cell wall is membrane
    • -some have flagella
    • - photosynthetic
  34. what are the characteristics of Cyanobacteria?
    • -photosynthetic
    • -contain chlorophyll
    • -found on water+land
    • -first to recolonize after nat. disaster
  35. characteristics of archaebacteria?
    -live in extremely harsh environments
  36. characteristics of prochlorobacteria?
    • -contain chlorophyll A and B as principal pigments
    • - similar to chloroplasts of plants
    • -only 2 species discovered
  37. What are the three cell shapes of monerans?
    • -rod
    • -sphere
    • -spiral
  38. What are the characteristics of Bacilli?
    • -rod
    • -produce endospores (dormant, waiting for ideal conditions)
    • -gram positive
  39. what are the characteristics of Cocci?
    • -Spherical
    • -grow in colonies of two cells
    • -long chains
    • - clumps or clusters
  40. what are the characteristics of spirilla?
    • -spiral
    • - possess bipolar tufts of flagella
  41. What are the different types of bacterial movement?
    • - propelled by flagella
    • - lash, snake, spiral forward
    • - glide on slimelike material
    • - sessile (no movement)
  42. What are the two major ways bacteria obtain energy?
    • Autotrophs
    • heterotrophs
  43. How do Autotrophic bacteria obtain energy?
    a) Phototrophic autotrophs : obtain energy from sunlight

    b) chemotrophic autotrophs: live in harsh environments, obtain energy from inorganic molecules
  44. How do heterotrophic bacteria obtain energy?
    a) chemotrophic heterotrophs: Break down organic molecules, most bacteria and animals

    b) phototrophic heterotrophs : Photosynthetic but also need organic compounds
  45. How can we look at the composition of the cell wall?
    using gram staining
  46. what 2 chemicals are used for gram staining?
    crystal violet (purple)

    safranine (red)
  47. What does it mean when bacteria takes up the crystal violet chemical?
    • -gram positive
    • eg. clostridium tetanus
  48. what happens when bacteria take up the safranine chemical?
    • -gram-negative bacteria
    • *more toxic, more resistant to antibiotics

    eg: e coli.

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