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BIO205-CH3-Microscop
BIO205 - Ch 3 -Observing Microorg. Through Microscope - RioSalado - AZ
| Question | Answer |
|---|---|
| Micrometer | 10^-6 m |
| prefix micro | Means unit following should be divided by 1 million |
| nanometer (nm) | 10^-9 m |
| Quorum | Ability of bacteria to communicate & coordinate behavior - group comes together, secrete "inducer" that changes behavior. |
| In compound microscope, light rays from an __ pass through a __ that has lenses to direct rays. | illuminator, condenser |
| Lenses closest to specimen | objective lenses |
| eyepiece | occular lenses |
| How is total magnification of compound light microscope calculated? | Objective lense magnification (power) times the ocular lense magnification (power). |
| Resolution | Resolving power - ability of lenses to distinguish fine detail & structure - distinguish 2 points a specific distance apart. |
| The __ the wavelength of light, the greater the resolution. | shorter |
| The white light in compound light microscope has __ wavelength. | long - cannot resolve smaller than 0.2 micrometer |
| Max magnification of compound light microscope. | 2000x |
| Refractive index | Measure of light-bending ability of a medium. |
| How do you change refractive index of specimens? | By staining them - they will then have different refractive indexes. |
| Immersion oil has same __ as glass. | refractive index - keeps light rays from refracting as they enter air - increases resolving power of lenses. |
| Brightfield illumination | Uses visible light for illumination - white background. |
| Darkfield microscope | Used for invisible microorganisms & cannot be stained - uses darfkield condenser with opaque disk - sees only reflected light - black background. |
| 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. |
| Differential interference contrast (DIC) microscopy | Measures differences in refractive indexes - 2 beams of light split by prisms & add contrasting colors - higher resolution - 3D. |
| Fluorescense | Ability of substances to absorb short wavelengths (ultraviolet) & give off longer length (visible) - glowing |
| Fluorescence microscopy | Organism stained with dye to glow (fluorochromes) & viewed under ultraviolet light against dark background. |
| Principal use of fluorescence microscopy | FA - fluorescent - antibody technique/immunoflorescence - can detect bacteria, etc w/in cells by viewing if specific antibodies attach. |
| Confocal microscopy | 3D image made by light microscope - uses fluorescent stains & laser - computer constructs image from stack of images - ATP & Ca ion concentrations. |
| Scanning Acoustic Microscopy (SAM) | Evaluates sound waves sent through specimin - used to study living cells attached to another surface - cancer cells, artery plaque, & biofilms. |
| What feature of confocal microscopy eliminates blurring? | Use of pinhole aperture |
| Principal use of SAM | Study living cells attached to another surface - cancer, plaque, etc. |
| Images produced by electron microscope are always __. | in black & white |
| 2 types of electron microscope. | Transmission - thin sections of a specimen & scanned - 3d view of surface. |
| Positive staining | Salts of various heavy metals used as stains & fixed onto specimens. |
| Negative staining | Increase electron opacity of surrounding field & useful when studying very small particles/specimins like virus particles, bacterial flagella, proteins. |
| Shadow casting | Heavy metals adhere at 45 degree angle on one side & leaves a shadow to crate 3d for size. |
| TEM has __ resolutions & valuable for examining __ of specimen. | high - layers |
| Drawback of TEM? | Only thin specimens - kills specimen & causes shrinking & distortion - artifacts. |
| Scanning Electron Microscope (SEM) | 3d view of surface - good for intact cells & viruses - uses electrons |
| Scanned-probe microscopes | Doesn't modify specimen or damage it - map atomic & molecular shapes, characterize magnetic & chemical properties, & temp variation inside cells. |
| Scanning tunneling microscopy (STM) | Thin metal (tungsten) probe scans specimen & produces an image revealing bumps & depressions of the atoms on surface of specimen. |
| Atomic Force Microscopy (AFM) | Metal & diamond probe - 3d image - doesn't damage specimen - both biological substances & molecular processes. |
| Stains are __ composed of positive & negative ion. | salts |
| The color of __ dyes is in the positive ion. | basic |
| The color of __ dyes is in the negative ion. | acidic |
| Name some basic dyes | crystal violet, methylene blue, malachite green & safranin |
| Most commonly used dyes | Basic dyes - methylene blue |
| __ dyes are not attracted to most types of bacteria. | Acidic - repelled by negatively charged bacterial surface. |
| Negative staining is used when for bacteria? | To prepare colorless bacteria against colored background - eosin, acid fuchsin, & nigrosin |
| Simple stain | Aqueous or alcohol solution of single basic dye. |
| Mordant | Chemical that increases affinity of stain for biospecimen or coats it. |
| Differential stains | React differently with different bacteria & used to identify - gram stain & acid-fast stain. |
| Gram stain | Stain that classifies bacteria into gram-positive & gram negative. |
| 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. |
| Primary stain | Basic purple dye (crystal violet) |
| Decolorizing agent | Alcohol/acetone solution to remove purple from some cells. |
| Gram-positive | Bacteria retaining color of purple dye & iodine after decolorization. |
| Gram-negative | Lose dark violet color after decolorization. |
| Counterstains | Basic dye safrain that turn gram-negative bacteria pink - doesn't affect gram-positive. |
| 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. |
| Gram-___ bacteria tend to be killed by penicillins & cephaliosporins. | positive |
| Acid-fast stain | Binds to bacteria with waxy material in cell walls - mycobacterium tuberculosis & leprosy. |
| What diseases can be diagnosed using acid-fast stain? | Tuberculosis & leprosy |
| Special stains | Used to color & isolate special parts of microorganisms & to find capsules. |
| Capsule | Gelatinous covering - determines organism's virulence |
| Virulence | Degree to which pathogen can cause disease. |
| Endospore | Cannot be stained by ordinary methods - resistant structure formed inside same bacteria which protects it from adverse environment. |
Created by:
Ladystorm
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