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40 Cards in this Set
- Front
- Back
What are the 5 I's in studying microorganisms?
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1. The Five I's
• Inoculation • Incubation • Isolation • Inspection • Identification |
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Explain Inoculation.
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• Introducing a sample (the inoculum) into a container with a nutrient medium
• The medium contains appropriate nutrients that sustain the growth of microorganisms • Some microbes have to be inoculated into a living organism *some microorganisms can not live in artificial mediums, they do not multiple or grow *Example: viruses |
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Explain Isolation.
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• Isolation: Separating one species from another
• Obtaining Pure Culture • Cultures composed of cells arising from a single cell- Pure Cultures *individual cells multiple and produce a clone which eventually becomes visible within the naked eye *pure culture is a culture that rises from a single cell *calling it a clone can also be correct |
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What are the methods to obtain a pure culture?
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•Streak Plate method
•Dilution method *could not obtain pure culture before cause it wasn't the right medium *one colony is one pure culture *dilution method requires you to dilute samples in such a way that it will inoculate into others it will produce a colony |
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What are the measures to take when working with microbiological medial?
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• Need to be sterilized
• Prevent contamination |
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Name the physical types of media?
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-Liquid
-Solid (layer) |
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Name the chemical compositions of media.
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-Synthetic
- Nonsythetic (Complex) |
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Name the functional types of media.
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• 3.Functional Type
- General type (not specific) - Enrichment (specific) -Selective -Differential |
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What is synthetic media?
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• Known chemical composition (NaNO3 - 3g/k glucose 2g/l…)
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What is nonsynthetic media?
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• Contains chemically undefined components (pepton, beef extract…)
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What does enrichment media do?
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Supports the growth of a specific group of microorganism (Ex. N2-Fixing)
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What is selective media?
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Favor specific microorganisms and inhibits the others (methylene blue inhibits the growth of Gram+ bacteria)
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What is differential media?
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Contain substances that permit detection of microorganisms with specific metabolic activity (blood agar)
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Explain Incubation.
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Microbiological media are placed in temperature controlled chambers (incubators)
temp- 20-40C Pathogenic- 37C ( Human body temp!) |
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Who invented the compound microscope?
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• Robert Hooke
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How does a microscope work?
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• The specimen is magnified with the objective lens (real image)
• This image is magnified by ocular lens (virtual image) • An enlarged and inverted image is received by retina |
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What are the basic features of microscopy?
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• Magnification
• Resolution • Contrast |
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What is magnification?
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results of Light Refraction
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What are the color coded objective lens and their magnifications?
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Smallest objective lens = 4x (40x) (red)
10x (100x) (yellow) 40x (400x) (blue) 100 (1000x) (green/black) |
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Why use oil immersion?
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Use with higher powder objectives.
Immersion oil has the same refraction index as the glass. Refractive index is a measure of relative velocity at which light passes through a material. *refraction index of immersion oil is the same as glass |
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What is resolution?
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Resolution (resolving power) is the ability of a lens to distinguish two adjacent points as two separate objects. In light microscopes resolution is 0.2 μm (limit - 2000x)
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Which images can be resolved?
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Anything larger than 0.2 um (bacteria)
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How does the resolution depend on the wavelength?
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• Resolving distance = wavelength of light /2x NA
•The shorter the wavelength - the greater the resolution |
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Explain Contrast in terms of microscopy.
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• Specimen must contrast with their medium
• Change the refractive index of specimen •Stain the specimen •Refractive index - a measure of light bending ability |
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What are the types of light microscopes?
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1.Bright field
2.Phase contrast 3.Fluorescent 4.Dark field 5.Differential 6.Interference 7.Confocal |
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What are the types of electron beam microscopes?
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1.Transmission
2. Scanning |
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What are the parts of light microscopy?
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• Illuminator
-so there is a light • Condenser -makes the light smaller • Objective Lens • Ocular Lens (eyepiece) |
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Explain dark field microscopes?
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• Best for observing pale objects
• Only those light rays scattered by specimen enter objective lens • Specimen appears light against dark background • Increases contrast and enables observation of more details *advantages: increases contrast, can see more detail in cells that normally not seen in bright-field microscopy |
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Explain Fluorescent Microscopy.
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*Fluorescent is the ability of certain substances to absorb short wavelength of light and emit light at a longer wavelength *makes it glow*
*in a spectrum, dyes absorb a short wavelength and illuminate length a different wavelength: longer |
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Explain Immunofluorescence as a diagnostic procedure.
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• Antibody produced against a specific bacterium
• Conjugate antibody and fluorochrome • Treat the unknown bacterium • If suspected bacteria present they will bind tagged antibodies • Ultraviolet (or near) light is used as a light source |
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Explain phase microscopes?
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Provides better contrast and more details in the cell.
The light rays that hit the specimen travel a different path than the rays, which do not hit the specimen. *rays are in phases (all in the same phase), sometimes it's possible for rays to be out of phase *the light rays get deviated by specimen is 1/4 wavelength out of phase -> phase plate deviates the rate even further -> deviated ray is now 1/2 wavelength out of phase |
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Explain Differential Interference Microscopy (Nomarsky) .
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• uses two beams of light
• Produces contrast from refractive index gradients • Higher resolution • 3-D images |
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Explain Confocal Microscopy.
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• Also uses fluorescent dyes
• Use UV lasers to illuminate fluorescent chemicals in a single plane of the specimen that is not thicker than 1.0 μm • Resolution increased by up to 40% because emitted light passes through pinhole aperture • Computer constructed 3-D images |
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Name some advantages of using EM?
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• Resolving distance = Wavelength of light 2
Wavelength of visible light = 4000A - Resolution light microscopy : 2000A (2 μm) • E.M. uses an electron beam as a source of illumination (100,000 times shorter wavelength than visible light) -Resolution (EM): 2 A - Objects are magnified 10,000X to 100,000X |
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Explain transmission electron microscope.
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• Image formed by the electrons transmitted through a specimen
• A specimen is a thin section of material (fixed, embedded, and sliced - never alive) • TEM - objects smaller than 0.2 mm |
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What is the preparation of a specimen for TEM image?
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• Fixation
• Dehydration • Embedding with plastic • Sectioning • Staining |
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Explain Scanning Electron microscope.
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• Used to study the surface of the cell/tissue
• The beam scans the surface • Image is formed by the electrons reflected from the surface • 3-D view |
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What is the preparation of specimens for optical microscopes?
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• Wet Mount (living) preparation
• Unstained • Stained (methylene blue) • Heat fixed smear • Thin film of material containing microorganisms is spread over the surface of the slide Air dried Heat fix (kill and fix bacteria to the slide) |
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Name the two differential stains?
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-Gram Stain
- Acid-Fast Stain |
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What are the special stains?
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- Negative (Capsule) Stain
- Flagellar Stain - Fluorescent Stains -Endospore Stain |