Term
What are the important parts of a microscope? |
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Definition
- Framework: arm
- Stage: holds slide and moves it around stage
- Lens system
-Oculars: eyepiece lenses
-Objectives: lenses attached to rotable nosepiece (4x,10x,45x,100x-oil immertion lens-)
-Condenser: directs light towards objective lens
-Iris Diaphragm |
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Term
What can be possibly done to improve resolution (resolving power)? |
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Definition
d, which is the smallest distance between two objects which can be seen as separate, can be decreased by lowering λ(wavelength of light) or increasing the NA(numerical aperture)
d=λ/2NA |
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Term
What is the formula to determine the total magnification of an object in a compound microscope? |
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Definition
Mag(total)= Mag(objective) * Mag(ocular)
-Objective: nosepiece lens (4x,10x,45x,100x)
-Ocular: eyepiece lens (usually 10x) |
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Term
What are the 3 principle forms of microorganisms revealed by a light microscope? |
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Definition
- Cocci: more or less spherical organisms
- Bacilli: Cylindrical organisms
- Helicoidal: Spiral shaped
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Term
What are the different patterns in which cocci may appear when incompletely separated? |
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Definition
- Diplococci(pairs): divide in one plane
- Steptococci(chains): divide in one plane
- Tetracocci(tetrads): divide in two planes
- Staphylococci(clusters): divide in three planes irregularly
- Sarcinae(cuboidal packets): divide in three planes regularly
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Term
What are the different cylindrical shapes in which Bacilli can appear?
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Definition
- Coccobacillus: very short, spherical, slightly longer in one direction than other.
- Fusiform Bacilli: tapered at the ends, 'football' shaped
- Filamentous Bacillary: forms grow in long threds
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Term
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Definition
Organic compounds containing a chromophore with affinity for cellular material. |
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Term
What are the different types of dyes? |
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Definition
- Cationic: basic dyes, + charged chromophore
Methylene Blue, Crystal Violet
- Anionic:acidic dyes,- charged chromophore
Acid fuschin, Congo Red, Nigrosin
Sudan Black Stain granules of Poly0B-OH-Butyric acid
- Insoluble Dyes:water insoluble
India Ink |
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Term
What are the types of staining procedure? |
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Definition
- Negative Staining
- Simple Staining
- Differential Staining
- Structural Staining
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Term
Explain the negative stain procedure |
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Definition
- Stains background, not the cell in brightfield microscopy
- Uses 2 dyes:
- Nigrosin-black anionic charged dye, repelled by the - charged surface of bacterial cell
- India Ink-(colloidal suspension of carbon particels) doesn't penetrate cell surface
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Term
Explain the simple stain procedure |
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Definition
- One dye used to stain all cells the same color. Can be used to tell morphology and size. Cationic (+) dyes are attracted by ionic forces to the - charged surface of bacterial cell.
- Common dyes are methylene blue and crystal violet.
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Term
Explain differential stain procedure
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Definition
- Causes cells to stain differently based on properties of the cell
- Two examples are:
- Gram Stain
- Acid Fast Stain
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Term
Explain Gram stain procedure. |
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Definition
- Causes the cell to stain differently based on characteristics of their cell wall.
- Gram+ microorg. have a higher peptidoglycan and lower lipid content than Gram-.
- Cells are stained with crystal violet, then fixed with iodine forming a crystal violet-iodine complex within the cell. Ethanol is then added as a decolorizer.(Gram- cells are easily decolorized because the ethanol dissolves the high lipid cell wall allowing the crystal violet-iodine complex to readily exit the cell. Gram+ cells resist decolorization due to the difference in cell wall consistency retaining the crystal violet-iodine complex). The Gram- cells are then counterstained with saffranin.
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Term
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Definition
- Acid fast microorganisms have a high wax content in their walls, which requires the use of steam to allow dye to penetrate the cell.
- Cells are steamed in the presence of carbol fuschin and decolorized with acid alcohol.
- Cells which are "acid fast" will not decoloried and remain red, while non acid fast organisms will readily lose their stain and become colorless.
- These cells are then counterstained with Methylene blue.
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Term
What are the two genera of Acid fast organisms? |
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Definition
- Mycobacterium: Do not gram stain well if mature because of high wax content within walls (if youn appear as gram + tapered rods that sometimes fragment)
- Two important species: Tuberculosis and leprae
- Nocardia
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Term
Explain structural staining |
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Definition
- Spore staining: To stain spores, the cells must be steamed to allow for the dye (malachite green)to enter the spores.Once the spores are stained, all other microorganisms can be easily decolorized with water. The other microorganisms and vegetative cells are then counterstained with Safranin.
- Endospores: green center with a pink sporangium
- Free spores:small green oval bodies
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Term
What are the 3 genera of spore forming organisms? |
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Definition
- Bacillus: areobic, gram+ rod
- Clostridium: anaerobic, gram+ rod
- Sporsacinae: cocci
-Anaerobic green: endospore/free spores clostridium
-Aerobic green: endospore/free spores of bacillus
-Anaerobic pink:vegetative/sporangia of clostridium
-Aerobic Pink:vegetative/sporangia of bacillus
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Term
What are the five methods of tube media transfer? |
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Definition
- Pour: 15-20 ml of liquid agar used to pour into plate
- Broth: 5-7 ml of liquid media
- Deep: 5-7 ml of media which has solidified in an upright position
- Slant: 5-7ml of media which has solidified at an angled position
- Fermentation broth: broth with Durham Tube added
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Term
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Definition
media composed of complex raw materials whose actual chemical composition is unknown (nutrient agar) |
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Term
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Definition
Media whose exact chemical composition is known and in many instances is design for isolation,selection or differentiation of specific types of microorganisms. |
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Term
What are the 2 types of synthetic media? |
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Definition
- Selective media: a media which favors the growth of one type of microorganisms over another. Accomplished by either inhibiting unwanted microorganisms or enriching
- Differential media: a media which differentiates or distinguishes between different types of microorganisms based on differences in appearance of growth or color changes.
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