BIO205 - Ch 3 -Observing Microorg. Through Microscope - RioSalado - AZ
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| Micrometer | 10^-6 m
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| prefix micro | Means unit following should be divided by 1 million
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| nanometer (nm) | 10^-9 m
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| Quorum | Ability of bacteria to communicate & coordinate behavior - group comes together, secrete "inducer" that changes behavior.
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| In compound microscope, light rays from an __ pass through a __ that has lenses to direct rays. | illuminator, condenser
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| Lenses closest to specimen | objective lenses
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| eyepiece | occular lenses
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| How is total magnification of compound light microscope calculated? | Objective lense magnification (power) times the ocular lense magnification (power).
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| Resolution | Resolving power - ability of lenses to distinguish fine detail & structure - distinguish 2 points a specific distance apart.
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| The __ the wavelength of light, the greater the resolution. | shorter
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| The white light in compound light microscope has __ wavelength. | long - cannot resolve smaller than 0.2 micrometer
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| Max magnification of compound light microscope. | 2000x
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| Refractive index | Measure of light-bending ability of a medium.
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| How do you change refractive index of specimens? | By staining them - they will then have different refractive indexes.
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| Immersion oil has same __ as glass. | refractive index - keeps light rays from refracting as they enter air - increases resolving power of lenses.
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| Brightfield illumination | Uses visible light for illumination - white background.
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| Darkfield microscope | Used for invisible microorganisms & cannot be stained - uses darfkield condenser with opaque disk - sees only reflected light - black background.
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| Phase-contrast microscope | Good to examine interior cell structures - Used with living microorganisms - don't have to fix them - uses special condenser to absorb refracted light & interference patterns.
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| Differential interference contrast (DIC) microscopy | Measures differences in refractive indexes - 2 beams of light split by prisms & add contrasting colors - higher resolution - 3D.
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| Fluorescense | Ability of substances to absorb short wavelengths (ultraviolet) & give off longer length (visible) - glowing
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| Fluorescence microscopy | Organism stained with dye to glow (fluorochromes) & viewed under ultraviolet light against dark background.
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| Principal use of fluorescence microscopy | FA - fluorescent - antibody technique/immunoflorescence - can detect bacteria, etc w/in cells by viewing if specific antibodies attach.
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| Confocal microscopy | 3D image made by light microscope - uses fluorescent stains & laser - computer constructs image from stack of images - ATP & Ca ion concentrations.
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| Scanning Acoustic Microscopy (SAM) | Evaluates sound waves sent through specimin - used to study living cells attached to another surface - cancer cells, artery plaque, & biofilms.
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| What feature of confocal microscopy eliminates blurring? | Use of pinhole aperture
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| Principal use of SAM | Study living cells attached to another surface - cancer, plaque, etc.
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| Images produced by electron microscope are always __. | in black & white
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| 2 types of electron microscope. | Transmission - thin sections of a specimen & scanned - 3d view of surface.
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| Positive staining | Salts of various heavy metals used as stains & fixed onto specimens.
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| Negative staining | Increase electron opacity of surrounding field & useful when studying very small particles/specimins like virus particles, bacterial flagella, proteins.
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| Shadow casting | Heavy metals adhere at 45 degree angle on one side & leaves a shadow to crate 3d for size.
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| TEM has __ resolutions & valuable for examining __ of specimen. | high - layers
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| Drawback of TEM? | Only thin specimens - kills specimen & causes shrinking & distortion - artifacts.
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| Scanning Electron Microscope (SEM) | 3d view of surface - good for intact cells & viruses - uses electrons
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| Scanned-probe microscopes | Doesn't modify specimen or damage it - map atomic & molecular shapes, characterize magnetic & chemical properties, & temp variation inside cells.
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| Scanning tunneling microscopy (STM) | Thin metal (tungsten) probe scans specimen & produces an image revealing bumps & depressions of the atoms on surface of specimen.
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| Atomic Force Microscopy (AFM) | Metal & diamond probe - 3d image - doesn't damage specimen - both biological substances & molecular processes.
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| Stains are __ composed of positive & negative ion. | salts
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| The color of __ dyes is in the positive ion. | basic
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| The color of __ dyes is in the negative ion. | acidic
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| Name some basic dyes | crystal violet, methylene blue, malachite green & safranin
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| Most commonly used dyes | Basic dyes - methylene blue
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| __ dyes are not attracted to most types of bacteria. | Acidic - repelled by negatively charged bacterial surface.
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| Negative staining is used when for bacteria? | To prepare colorless bacteria against colored background - eosin, acid fuchsin, & nigrosin
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| Simple stain | Aqueous or alcohol solution of single basic dye.
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| Mordant | Chemical that increases affinity of stain for biospecimen or coats it.
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| Differential stains | React differently with different bacteria & used to identify - gram stain & acid-fast stain.
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| Gram stain | Stain that classifies bacteria into gram-positive & gram negative.
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| 4 steps of gram staining | (1) basic purple dye (primary) applied, (2) dye washed off & mordant applied, (3) alcohol-acetone solution (decolorized), (4) basic red dye applied.
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| Primary stain | Basic purple dye (crystal violet)
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| Decolorizing agent | Alcohol/acetone solution to remove purple from some cells.
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| Gram-positive | Bacteria retaining color of purple dye & iodine after decolorization.
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| Gram-negative | Lose dark violet color after decolorization.
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| Counterstains | Basic dye safrain that turn gram-negative bacteria pink - doesn't affect gram-positive.
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| What reacts to create gram stain? | Structural differences in cell wall - gram-positive have thicker peptidoglycan cell wall, gram-negative have lipopolysaccharides in cell wall.
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| Gram-___ bacteria tend to be killed by penicillins & cephaliosporins. | positive
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| Acid-fast stain | Binds to bacteria with waxy material in cell walls - mycobacterium tuberculosis & leprosy.
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| What diseases can be diagnosed using acid-fast stain? | Tuberculosis & leprosy
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| Special stains | Used to color & isolate special parts of microorganisms & to find capsules.
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| Capsule | Gelatinous covering - determines organism's virulence
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| Virulence | Degree to which pathogen can cause disease.
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| Endospore | Cannot be stained by ordinary methods - resistant structure formed inside same bacteria which protects it from adverse environment.
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