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55 Cards in this Set
- Front
- Back
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Types of microscopes that use light to illuminate specimen |
Light microscopy Confocal microscopy Fluorescent microscopy |
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Fluorescent microscopy |
Uses UV light to cause fluorochromes to emit visible light |
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Fluorochromes |
Dyes that emit visible light under UV rays Can be combined with antibodies to help identify unknown bacteria |
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Confocal Microscopy |
Cells are stained with fluorochrome dyes Short- wavelength (blue) light is used to excite dyes Light illuminates each plane in the specimen to create 3D image Most use computers to construct image |
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Electron Microscope |
Uses electrons instead of light to give greater resolution (due to shorter wavelength) |
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Types of electron microscopes |
Transmission Electron Microscopes Scanning Electron Microscopes |
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Transmission Electron Microscope |
Produce 2D images of a slice of the specimen |
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Scanning Electron Microscopes |
Give a 3D image |
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Under light microscopy, what can be done to better observe bacteria? What does this allow us to observe? |
Staining Morphology and arrangement |
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Stains |
Salt molecules with a positive and negative ion |
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Dimensions of bacterial cells |
Length: 2-8um (micrometer) Diameter: 0.2-2um |
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Morphology of bacterial cells |
Cocci Bacilli Spirals |
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Cocci |
Spherical shaped |
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Bacilli |
Rod shaped |
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Spirals |
Spiral shaped |
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Arrangements/variations of cocci |
1. Diplococci 2. Streptococci 3. Tetrad 4. Sarcinae 5. Staphylococci |
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Diplococci |
Arrangement of 2 cocci |
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Streptococci |
Chain of cocci |
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Tetrad |
Arrangement of 3 cocci |
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Sarcinae |
Arrangement of 4 cocci |
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Staphylococci |
Packets of 8 cocci |
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Arrangements and variations of bacilli |
Diplobacilli Streptobacilli Coccobacilli |
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Diplobacilli |
Arrangement of 2 bacilli |
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Streptobacilli |
Chain of bacilli |
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Coccobacilli |
Almost spherical bacilli |
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Arrangements and variations of spirals |
No arrangements! Vibrio Spirilla Spirochete |
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Vibrio |
Comma shaped Slightly bent rod |
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Spirilla |
Inflexible spirals Stuck in corkscrew shape |
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Spirochete |
Flexible spirals |
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Monomorphic |
Always one shape Most bacteria fit this description |
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Pleomorphic |
Can take different shapes under different conditions |
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Motility |
Directed movement |
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____ spiral bacteria are motile |
All |
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____ of bacilli are motile |
About 1/2 |
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____ of cocci are motile |
Almost none |
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Bacterial flagella |
Less complex than eukaryotic flagella Whip like projections used to move around |
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Main parts of flagella |
1. Filament 2. Hook 3. Basal body |
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Filament |
Long outer most region of the flagella |
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Hook |
Slightly wider section at the base of the flagella that the filament attaches to |
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Basal body |
Anchors the flagella to the cell wall |
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Flagella classifications |
Monotrichous Ampitrichous Lopotrichous Peritrichous |
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What type of motility do bacteria with flagella typically display? |
"Run and tumble" Run: bacteria moves in a straight line for an extended period of time Tumble: bacteria twirls in place to change direction |
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Flagella stain |
A stain using mordant: a chemical that adheres to tissue and intensifies the reaction between dye and flagella, making them more visible |
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Advantages of motility |
Allows bacteria to move towards or away from stimuli |
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Types of motility |
(Positive or Negative): Chemotaxis Phototaxis Aerotaxis |
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Chemotaxis |
When chemicals are the stimuli that cause movement |
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Phototaxis |
When light is the stimulus that causes movement |
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Aerotaxis |
When air (O2) is the stimulus that causes movement |
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Positive motility |
When the organism moves toward a stimulus |
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Negative motility |
When an organism moves away from a stimulus |
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Modes of motility |
Axial filament (endoflagella) Fimbriae Pili |
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Axial filament |
Found only in spirochetes Formed by protein fibers called endoflagella that wraps around the inside of the cell and contract like muscle fiber |
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An example of a spirochete |
Trponema pallidum |
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Fimbriae |
- Filamentous appendages that are shorter, straighter, and more numerous than flagella - Found mostly in Gram (-) bacteria - Mostly used for attachment, not motility |
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Pili |
- Typically longer than fimbriae - Usually only one or two per cell - Can be used in gliding or twitching motility - Also used in transferring genes from one bacteria to another |
