micro lecture 3

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  1. observing microorganisms thru a microscope
    ever wonder how many diseases there are? as of 2003 or so, about 1450 different species of human pathogen were known, which many of them having a wide variety of "strains" or varieties. 60% of them can be contracted from animals, while the remaining 40% are associated only with humans
  2. List the metric units of measurement, including their metric equivalents that are used for microorganisms
    • King (kilo)
    • Henry (hecto)
    • Drinks (deca)
    • Ulcky (base units: meter liter gram)
    • Dark (deci)
    • Chocolate (centi)
    • Milk (mili)
    • (six hops from base to get to:)
    • Micro (10e-6)
    • (nine hops from base to get to:)
    • Nano (10e-9)
  3. diagram the path of light thru a compound microscope
    a specimen is magnified as light passes thru the objective and ocular lenses
  4. define total magnification and resolution
    • total magnification is calculated by multiplying the magnification of the objective lens by the magnification of the ocular lens (10x)
    • resolution is the ability of the lenses to distinguish two points
  5. explain how electron microscopy differs from light microscopy
    • a bean of electrons, instead of light, is used with an electron microscope
    • electromagnets, instead of glass lenses, control focus, illumination, and magnification
    • thin sections of organisms can be seen in an electron micrograph produced using a transmission electron microscope
    • three-dimensional views of the surfaces of whole microorganisms can be obtained with a scanning electron microscope
  6. differentiate between an acidic dye and a basic dye
    • acidic dye: the chemical used is negatively charged (staining the background..not often used)
    • Basic dye: positively charged chemical is used to stain
  7. compare simple, differential and special stains
    • simple stain: use of a single basic dye
    • -a mordant may be used to hold the stain or coat the specimen to enlarge it
    • differential stain: uses two diferent colored dyes
    • -ex: gram stain
    • special stains: emphasizes certain cell parts
    • -ex: capsule stain
  8. list the steps in preparing a Gram stain, and describe the appearance of gram-positive and gram-negative cells after each step
    • first step use sthe first stain crystal violent (stains everything purple)
    • than add the mordant (grams iodine) to help the chemical reaction along
    • than wash with alcohol to decolorize anything that isn't chemically bonding
    • than use the last stain: safranin (counterstaining)

    • Image Upload 1
    • the gram pos bacteria retain the purple stain after the decolorization step
    • gram neg bacteria do not and thus appear pink from the counterstain
  9. compare and contrast the Gram stain and the acid-fast stain
    it only stains one certain genus of bacteria; the micro bacteria because they have acid alcohol outside their cell walls

    • acid-fast microbes, such as members of the genera Mycobacterium and Nocardio, retain carbolfuchsin after acid-alcohol decolorization and appear red
    • non-acid fast microbes take up the methylene blue counterstain and appear blue
  10. explain why each of the following is used: capsule stain, endospore stain, flagella stain
    to stain capsule, endospores or flagella to make them bigger to see
  11. define what is science
    • derived from Latin "to know"
    • science is a way of asking and answering questions
    • it seeks answers to question about natural phenomena
    • scientific thinking reduces emotional reactions
  12. list the steps of the scientific method
    • 1. observe an event
    • 2. develop a model (or hypothesis) which makes a prediction
    • 3. test the prediction (experiment)
    • 4. observe the result
    • 5. analyze the data
    • 6. make a conclusion
  13. define scientific theory and law
    • scientific theory: a description of the world that covers a relatively large number of phenomena and has met many observation and experimental tests
    • law of nature: theory (or group of theories) that has been tested extensively and seems to apply everywhere in the universe
  14. compare pie, bar and line graphs
    • bar graphs are used to show a comparison of multiple objects
    • pie graphs are used to compare the parts of a whole
    • line graphs are used to show the relationship between variables
  15. compound light-microscope
    has multiple lenses and uses visible light
  16. ocular
    "eye". on a microscope it means the eye piece you look thru
  17. objective lenses
    magnifies the object.. has four powers; 4x, 10x, 40x, 1000x
  18. total magnification
    is calculated by multiplying the magnification of the objective lens by the magnification of the ocular lens (10x)
  19. resolution
    the ability to see two separate things as separate
  20. staining
    coloring a microorganism with a dye to make some structures more visible
  21. fixing
    uses heat or alcohol to kill and attach microorganisms to a slide
  22. smear
    a thin film of material used for microscopic examiniation
  23. basic dyes
    the chemical used is positively charged
  24. acidic dyes
    the chemical used is negatively charged (staining the background..not often used)
  25. simple stain
    simple stain: use of a single basic dye
  26. mordant
    • -a mordant may be used to hold the stain or coat the specimen to enlarge it
    • (gram iodine)
  27. Gram stain
    • the gram stain classifies bacteria into gram-positive and gram negative
    • gram-positive bacteria tend to be killed by penicillin and detergents
    • gram-negative bacteria are more resistant to antibiotics
  28. differential stains
    • uses two different color dyes
    • ex: gram stain and acid-fast stain
    • they differentiate bacteria according to their reactions to the stains
  29. gram negative
    gram-negative bacteria are more resistant to antibiotics
  30. gram positive
    gram-positive bacteria tend to be killed by penicillin and detergents
  31. counter stain
    An additional dye used in a microscopy specimen to produce a contrasting background or to make clearer the distinction between different kinds of tissue.
  32. decolorizer
    an agent that removes color, bleaches.
  33. special stains
    • negative staining is used to make microbial capsules visible
    • the endospore stain and flagella stain are special stains that color only certain parts of bacteria
  34. hypothesis
    • educated guess
    • is testable and falsifiable
    • in science hypothesis are tested by using them to make predictions about the outcome of an experiment
  35. theory
    something that a lot of people tested and no one as proved wrong yet
  36. scientific method
    • more reliable for obtaining info
    • you can test what you believe to be true
    • others can repeat your experiment
    • opportunity to prove false
    • follows general set of systematic procedures
    • steps are followed in order to answer a research question
  37. independent variable
    condition or even under study (choose 1) [the collar]
  38. dependent variable
    condition that could change under the influence of the independent variable (measure this) [the number of fleas]
  39. assumption
    • factors throught to be true for the investigation but have not been verified or controlled
    • commonly accepted info
    • thought to be held constant but not controlled
    • factors beyond the investigators control bc of technical or time considerations
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micro lecture 3
micro lecture 3
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