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Questions and Answers
What structure is responsible for the rotational movement of bacterial flagella?
What is the movement called when flagella rotate counterclockwise?
What type of bacterium has a single flagellum at each pole of the cell?
How do bacteria respond when they detect a toxic substance?
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Which bacterial arrangement has flagella distributed over the entire surface?
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What is the term for the ability of bacteria to move towards or away from chemical stimuli?
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Which type of bacteria possesses two or more flagella at one or both poles?
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What kind of motion occurs when a bacterium briefly stops and rolls?
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Which structure inserts the flagellum into the bacterial cell?
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What is observed when using a hanging drop slide?
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What is the primary mechanism of movement employed by motile bacteria?
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Which structure is NOT a component of a bacterial flagellum?
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In which type of bacterial motility do organisms move only when in contact with a solid surface?
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What is the function of axial filaments in spirochetes?
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How does chemotaxis allow bacteria to navigate their environment?
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What are the two types of movements characterized by flagellar activity in bacteria?
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Which of the following best describes 'Brownian movement'?
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Which part of a bacterial flagellum is responsible for propelling the organism?
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What occurs when the flagella of a bacterium rotate clockwise?
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Which of the following statements is true about flagella in prokaryotic cells?
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Study Notes
Bacterial Motility
- About half of all known bacteria can move
- Brownian movement, where water molecules hit bacterial cells, is not considered true motility
- True motility is the purposeful movement of bacteria
- Motile bacteria use different mechanisms for movement
- Gliding motility allows bacteria to move over surfaces when in contact with a solid surface
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Corkscrew or bending motility is displayed by spirochetes due to the presence of axial filaments
- Axial filaments are modified flagella that wrap around the cell
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Flagella are the most common type of motility structure
- They are long, helical, semirigid appendages that move the cell by rotating
- Flagella rotate either clockwise or counterclockwise
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Chemotaxis: refers to the movement of bacteria in response to chemical stimuli
- Bacteria move towards attractants like nutrients and away from repellents like toxins
Flagellar Structure
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Filament: extends outward from the cell and rotates to propel the organism
- Composed of multiple units of flagellin protein in a helical arrangement
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Hook: connects the filament to the basal body
- Composed of a different type of protein
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Basal body: anchors the flagellum to the cell membrane
- Composed of a rod and a series of rings
- The number and location of the rings differ depending on whether the bacteria is gram-positive or gram-negative
Flagellar Arrangements
- Monotrichous: one flagellum at one end of the cell
- Amphitrichous: one flagellum at each end of the cell
- Lophotrichous: two or more flagella at one or both poles of the cell
- Peritrichous: flagella distributed over the entire surface of the cell
Bacterial Movement
- Run: The flagella rotates counterclockwise, propelling the bacteria forward
- Tumble: Flagella rotation reverses to clockwise, causing the bacteria to stop abruptly and roll about
- Bacteria adjust run and tumble frequency based on stimuli
- Longer runs and fewer tumbles when sensing attractants
- More frequent tumbles and shorter runs when sensing repellents
Hanging Drop Slide
- Useful for observing bacterial motility
- Allows for the observation of live microorganisms
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Description
This quiz explores the various mechanisms of bacterial motility, including gliding, corkscrew, and flagellar movements. Learn how bacteria navigate their environment through purposeful movements in response to stimuli like chemicals. Test your knowledge on the structure and function of bacterial motility components.
