Bacterial Cell Structure
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Questions and Answers

What is the function of capsules on bacterial surfaces?

  • To aid in bacterial movement
  • To provide a protective covering against phagocytic cells (correct)
  • To adhere to surfaces (correct)
  • To produce toxins

    • What is the primary function of flagella in bacterial cells?

  • To aid in bacterial movement and chemotaxis (correct)
  • To provide structural support to the cell
  • To facilitate nutrient uptake
  • To produce toxins

    • What is the primary function of endospores?

  • To facilitate nutrient uptake
  • To provide a survival strategy under sub-optimal conditions (correct)
  • To aid in bacterial movement
  • To produce toxins

    • What type of toxins cause cell lysis?

    <p>Cytotoxins</p> Signup and view all the answers

    What is the term for the directed movement of bacteria towards or away from chemicals?

    <p>Chemotaxis</p> Signup and view all the answers

    What is the primary function of exotoxins?

    <p>To inhibit host cell function</p> Signup and view all the answers

    What is the term for toxins that affect neurotransmitter release?

    <p>Neurotoxins</p> Signup and view all the answers

    What is the term for the excessive immune response caused by some toxins?

    <p>Superantigens</p> Signup and view all the answers

    What is the primary function of fimbriae in bacterial cells?

    <p>To enable organisms to adhere to surfaces</p> Signup and view all the answers

    What is the main target of chemotherapy in bacterial infections?

    <p>Cell wall</p> Signup and view all the answers

    What is the name of the major molecule in the bacterial cell wall?

    <p>Peptidoglycan</p> Signup and view all the answers

    What is the purpose of the cell envelope in bacterial cells?

    <p>To protect the cell's internal environment</p> Signup and view all the answers

    What is the result of fimbriae preventing the flushing action of saliva, urine, etc. in humans and animals?

    <p>Increased risk of infection</p> Signup and view all the answers

    What is the main difference between Gram positive and Gram negative bacteria?

    <p>Cell wall composition</p> Signup and view all the answers

    Study Notes

    Bacterial Cell Structures

    • The lecture focuses on prokaryotic cells, with emphasis on components related to infection severity and bacterial cell protection.
    • The cell envelope and cell wall are crucial for protecting the cell's internal environment and providing shape and rigidity.

    Gram Staining and Bacterial Morphologies

    • Understand the difference between Gram positive and Gram negative bacteria.
    • Familiarize yourself with various bacterial morphologies.

    Bacterial Cell Surface Structures

    • Fimbriae are short protein structures that enable bacteria to adhere to surfaces and prevent flushing action.
    • Capsules are outer coverings of polysaccharide that provide partial protection from phagocytic cells and aid in biofilm formation.

    Internal Bacterial Structures

    • Endospores are bacterial survival strategies that occur when conditions are sub-optimal, allowing vegetative cells to convert to dormant, non-growing structures.
    • Endospores are highly resistant to heat, chemicals, and radiation and can be produced by only two genera of bacteria (Clostridium, Bacillus).

    Bacterial Movement

    • Bacterial motility is provided by flagella, which are long, thin hair-like structures attached to the bacterial cell.
    • Flagella act like propellers to propel bacteria forward or backward, allowing them to move towards desirable environmental conditions and away from undesirable chemical stimuli.

    Chemotaxis

    • Flagella can direct the cell towards desirable environmental conditions (food) and away from undesirable chemical stimuli (antibiotics) through chemotaxis.
    • In the absence of a chemical stimulus, the cell swims randomly (tumble), and in the presence of an attractant, the cell moves towards the gradient of the attractant (run).

    Secreted Bacterial Products

    • Exotoxins are toxic proteins actively secreted by organisms during growth, which can travel from the site of infection to distant sites via blood and tissues.
    • Exotoxins can be categorized based on their mechanism of action, including cytotoxins, neurotoxins, enterotoxins, and superantigens.

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    Description

    This quiz covers the components of a prokaryotic cell, including capsules, flagella, and the cell envelope, and their role in infections.

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