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chapter 2

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  • How do Stained endospores appear?
    green in a red/pink cell
  • What microscope would you use to view a ribosome
    TEM
  • Which microscopes would you use to observe unstained cells?
    Unstained cells are more productively observed using darkfield, phase-contrast, or DIC microscopy.
  • What is a scanning probe microscope used for?
    Scanning-probe can look at actual atoms, used for scanning surfaces at the nanoscale level
  • What SEM stand for and what is it used for?
    Scanning Electron Microscopy - Scans the surface. Produces 3D images
  • What are helminths typically  measured in?
    millimeters
  • Define total magnification and resolution.
    Total magnification - objective lens x ocular lens. The ocular lens is set to 10x. Resolution - the ability to distinguish two objects from eachother
  • Why is fixing necessary for most staining procedures?
    helps preserve morphology, ensures the little beasties will not run off or be washed off the slide
  • how are brightfield, darkfield, phase-contrast, and fluorescence microscopy similar?
    They all need a light source
  • Which type of microscopy is most likley used to observe stained cells?
    Bright field microscopy
  • Why do electron microscopes have greater resolution than light microscopes?
    Electrons have a sgorter wavelength than visible light. Produces a higher resolution image than light microscopes
  • What microscope would use to view specimens 200nm to 10mm
    light microscopes
  • What is a special stain? Name the 3 special stains in the slides and explain what they are used for
    capsule stain, endospore stain and flagella stain...
  • What are viruses typically measured in?
    nanometers
  • What is another word for micrometers
    micron
  • What microscope would you use to view the surface details of a virus?
    SEM, AFM
  • List Gram stain steps, and describe the appearance of gram-positive and gram-negative cells after each step.
    crystal violet; both purple; Gram's Iodine-both purple; Decolorize- (95% ETOH), (+) purple,(-) colorless;safranin-(-)pink(+)purple
  • how do acid fast negative bacteria appear after preforming an acid fast stain
    no mycolic acids in cell wall so unable to retain carbolfuschin after decolorizing step. instead take up the counterstain (methylene blue) and appear blue
  • What lenses does light pass through in a compound microscope?
    condenser lenses, objective lenses, ocular lens
  • how do acid fast positive bacteria appear after  preforming the acid fast stain
    acid fast retain the primary stain after decolorization with acid-alcohol due to the resistant nature of their cell walls. (mycolic acid)
  • How are electron microscopy and light microscopy different?
    electron microscopes use a beam of electrons instead of a beam of light. Electrons have a shorter wavelength than visible light. Higher resolution than light
  • What does TEM stand for and what is it used for?
    Transmission Electron Microscope - Reveals internal structures.
  • differentiate gram staining and endospore staining
    They both use 2 stains to differentiate microbes; differentiates between Gram(+)(-) appear purple/pink; endospore stain visulaizes endospore green in pink cell
  • What are prokaryotes typically measured in?
    micrometers
  • What microscope would you use to view the mitochondrial structure of a protozoan
    phase-contrast, fluorescence, TEM
  • Explain why negative staining involves acidic dyes. Give an example of an acidic dye
    uses acidic/anionic dye because its (-)charge is repelled by the (-) charge on the outside of the cell staining the background not the microbe/cell.  Nigrosin
  • Which stain would be used to identify microbes in the genera Mycobacterium and Nocardia?
    acid fast stain
  • What is the purpose of simple staining?
    Observe the morphology, shape/arrangement of cells.
  • What microscope would you use to view living bacteria in motion?
    brightfield, darkfield, phase-contrast
  • What is used as the mordant in gram staining and what does it do?
    The mordant is Gram's Iodine. This binds to the crystal violet making a large complex that adheres to the peptidoglycan cell wall. 
  • Why is the Gram stain so useful?
    helps to differentiate between gram (+) and gram (-) also can determine morphology which can help determine further physiological tests 
  • Differentiate an acidic dye from a basic dye.
    Basic dyes have a (+) charge; acidic dyes have a (-) charge; Basic dyes attract to (-) charged bacterial cell wall due to their (+) charge
  • Explain how the phase-contrast microscope works and what we use it for
    Brings direct and reflected or diffracted light rays together to form an image of the specimen on the ocular lens. used for detailed observation of living cell
  • What is one way fluorescence microscopy is used for?
    By labeling specific molecules or organelles with fluorescent markers, researchers can track their movement, localization, and interactions in living cells.
  • What does DIC stand for and what is it used for?
    Differential Interference Contrast, provides a colored, 3D image of living cells.
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