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30 Cards in this Set
- Front
- Back
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In what units are MOs measured?
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nanometer( nm)
picometer |
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name 4 types of microscope
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- simple
-compound -light -electron |
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feature simple microscope
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single lens microscope
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feature compound microscope
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2 or more lenses
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feature of light microscope
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uses visible light to illuminate object
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feature electron microscope
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uses electron beams
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4 types of compound light microscope
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-bright field microscope
-dark field microscope -phase contrast microscope -fluorescence microscope |
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feature of bright field microscope
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background is bright
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feature dark field microscope
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background is dark
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define working distance
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when imagine in is sharp focus
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give the light path
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light-----condenser lens------specimen-----objective lens-----ocular lens------eye
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why do we light microscope?
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cell absord of scatter light which create a contrast difference between the specimen and the background
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define parfocal
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ability of a microscope to keep focus from one objective lens to the next
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define magnification
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degree to whic the viewed object is enlarged or process of making the object larger
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total magnification
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objective lens magnification X ocular lens magnification
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define resolution
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ability of lens to distinguish 2 adjacents objects as separate and distinct entities
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define resolving power
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minimum distance between 2 distinguishable objects
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relationship between resolving power and minimum distance
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high resolution = smaller minimum distance
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relationship between resolving power and resolution
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smaller resolving distance = higher resolution
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what affects the resolution?
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the wavelength
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relationship between resolution and wavelength
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low wavelength = higher resolution
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purpose of oil immersion
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-achieve greater magnification
by minimizing light bending - has same refracting index as glass |
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define contrast
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difference in visual property to make object distinguishable form other or background
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how do you contrast?
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by using stain
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what are the two staining techniques?
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simple stain and differential stain
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what is a simple stain?
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application of one dye to stain cells such that they are vsible to the same color
example: methylene blue |
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what is a differential stain?
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application of two or more dyes to distinguish different cells parts or differents cells types
example: gram stain, spore stain |
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Gram stain is use to distinguish between what kind of bacteria
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-gram positive
- gram negative |
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what are the steps for gram stain?
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- primary stain ( crystal violet)-----all cells are purple
-mordant (iodine)------all cells remain purple -decolorizer (alcohol)-------G(+) purple and G(-) colorless -counterstain (safranin)------- G(+) purple and G(-) pink |
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characteristic of electron Microscope
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-use electron beams
-use magnetic lens to form image -has high resolution and magnification |
