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Questions and Answers
Which statement accurately describes the movement of spirochetes due to their axial filaments?
Which statement accurately describes the movement of spirochetes due to their axial filaments?
- They move exclusively in a straight line.
- They can only move in a backward motion.
- They exhibit a spiral or corkscrew-like movement. (correct)
- They move by undulating like cilia.
What type of bacteria possess flagella distributed over their entire surface?
What type of bacteria possess flagella distributed over their entire surface?
- Amphitrichous bacteria
- Peritrichous bacteria (correct)
- Lophotrichous bacteria
- Monotrichous bacteria
Which type of motility involves the use of pili?
Which type of motility involves the use of pili?
- Ciliary movement
- Amoeboid movement
- Gliding motility (correct)
- Flagellar propulsion
What is the primary function of fimbriae in bacteria?
What is the primary function of fimbriae in bacteria?
Bacteria that lack flagella are classified as what type?
Bacteria that lack flagella are classified as what type?
What is a key function of the bacterial capsule?
What is a key function of the bacterial capsule?
What distinguishes a slime layer from a capsule?
What distinguishes a slime layer from a capsule?
What structural component primarily makes up bacterial flagella?
What structural component primarily makes up bacterial flagella?
How does energy generation affect bacterial motility through flagella?
How does energy generation affect bacterial motility through flagella?
Which type of movement do spirochetes exhibit due to their unique flagellar structure?
Which type of movement do spirochetes exhibit due to their unique flagellar structure?
What is the term for the movement of bacteria toward or away from a chemical stimulus?
What is the term for the movement of bacteria toward or away from a chemical stimulus?
What pattern of movement do bacteria exhibit when they approach an attractant?
What pattern of movement do bacteria exhibit when they approach an attractant?
What does a flagellum NOT contain?
What does a flagellum NOT contain?
What is the primary feature of the glycocalyx that distinguishes it from other cell structures?
What is the primary feature of the glycocalyx that distinguishes it from other cell structures?
Which type of cell division is characteristic of prokaryotic cells?
Which type of cell division is characteristic of prokaryotic cells?
What is the main function of a slime layer in bacteria?
What is the main function of a slime layer in bacteria?
Which of the following best describes the structure of flagella in prokaryotic cells?
Which of the following best describes the structure of flagella in prokaryotic cells?
What are bacilli commonly characterized by?
What are bacilli commonly characterized by?
Which type of bacteria are described as being monomorphic?
Which type of bacteria are described as being monomorphic?
How do spirilla bacteria primarily move?
How do spirilla bacteria primarily move?
What is a common occurrence in the arrangement of diplo- and streptococci?
What is a common occurrence in the arrangement of diplo- and streptococci?
Study Notes
Glycocalyx
- A viscous, gummy material composed of sugars and proteins
- Produced by the cell membrane and secreted outside the cell.
- Classified as a slime layer or a capsule
Slime Layer
- Unorganized
- Only loosely attached to the cell wall
- Enables bacteria to glide or slide along solid surfaces
Capsule
- Organized and firmly attached to the cell wall
- Composed of polysaccharides, with possible combinations with lipids and proteins
- Protects bacteria from being engulfed by white blood cells (phagocytosis).
Flagella
- Threadlike protein appendages that enable bacteria to move.
- The presence of flagella indicates a motile bacterium
- Flagellated bacteria are about 10 to 20 nanometers (nm) thick
- Composed of protein fibers called flagellin, twisted together like a rope.
- Prokaryotic flagella do not have microtubules and are not membrane-bound.
Axial Filament
- Two flagella-like fibrils
- Wrap around the organism
- Enable spirochetes to move in a spiral or helical fashion
Flagellum Structure
- Arises from a basal body in the cell membrane
- Projects outward through the cell wall and capsule.
- A semirigid, helical structure that rotates from the basal body
- Rotation is clockwise or counterclockwise
- Flagellar rotation relies on continuous energy production by the cell
Bacterial Movement
- Bacteria can alter the speed and direction of flagellar rotation
- The movement of bacteria towards or away from a stimulus is called taxis
Chemotaxis
- Movement toward or away from chemical stimuli
- Oxygen, ribose, and galactose are examples of chemical stimuli
Phototaxis
- Movement toward or away from light stimuli
- Motile bacteria contain receptors to detect stimuli
Pili and Fimbriae
- Observed on Gram-negative bacteria
- Polymerized protein molecules called pilin, arranged in a helix
- Extend from the cytoplasm through the plasma membrane, cell wall, and capsule.
Fimbriae (Adhesin)
- Located at the bacterial cell poles or evenly distributed on the surface
- Important for bacterial attachment to surfaces
Pili
- Usually longer than fimbriae
- Typically only one or two per cell
- Involved in bacterial motility and DNA transfer
- Enable gliding motility.
Bacterial Shape
- Monomorphic: maintains a single shape
- Pleomorphic: can have multiple shapes
Prokaryotic Cell Structure
- All bacteria are prokaryotes
- Significantly smaller than eukaryotic cells
- Reproduction occurs through binary fission
- The cytoplasm contains a chromosome, ribosomes, and other particles
- Surrounded by a cell wall, sometimes with a capsule or slime layer
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Description
This quiz explores the various structures of bacteria, including glycocalyx, slime layers, capsules, flagella, and axial filaments. Understand the functions and characteristics of these structures and their role in bacterial motility and protection. Test your knowledge on prokaryotic cell structures!
