Bacterial Morphology and Cell Structure
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Questions and Answers

What is the function of mesosomes in bacterial cells?

  • Protein synthesis
  • Regulation of bacterial cell shape
  • Formation of cytoplasmic granules
  • Invagination of plasma membrane towards cytoplasm (correct)

    • What is the shape of Spirilla bacteria?

  • Rigid, curved, and comma-shaped
  • Spiral-shaped and tightly coiled (correct)
  • Rod-shaped and motile
  • Flexible, helical-shaped

    • What is the function of plasmids in bacterial cells?

  • Regulation of gene expression
  • Protein synthesis
  • Cell wall formation
  • Storage of genetic material (correct)

    • What is the characteristic of Mycoplasma bacteria?

    <p>Pleomorphic shape</p> Signup and view all the answers

    What is the function of the cytoplasmic membrane in bacterial cells?

    <p>Electron transport and energy generation</p> Signup and view all the answers

    What is the characteristic of Actinomyces bacteria?

    <p>Filamentous shape</p> Signup and view all the answers

    What is the function of transposons in bacterial cells?

    <p>Mobile genetic elements that can jump from one location to another</p> Signup and view all the answers

    What is the composition of the bacterial cell wall?

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

    What is the approximate percentage of the cell wall made up of peptidoglycan in Gram positive bacteria?

    <p>50-90%</p> Signup and view all the answers

    What is the function of lipoteichoic acid in Gram positive bacteria?

    <p>It acts as a receptor molecule for Gram positive bacteriophages</p> Signup and view all the answers

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

    <p>The thickness of the peptidoglycan layer</p> Signup and view all the answers

    What is the function of penicillin-binding proteins (PBPs) in bacterial cell wall synthesis?

    <p>They are essential for cell wall synthesis</p> Signup and view all the answers

    What is the term for bacteria that have lost their cell wall but can still multiply and divide?

    <p>L forms</p> Signup and view all the answers

    What is the term for the outer layer of the Gram negative bacterial cell wall?

    <p>Outer membrane</p> Signup and view all the answers

    What is the component of the Gram negative bacterial cell wall that is responsible for its toxicity?

    <p>Lipid A</p> Signup and view all the answers

    What is the term for the thin, high molecular weight secretory substance present in many bacteria external to the cell wall?

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

    What is the primary function of a capsule in bacteria?

    <p>To protect bacteria from environmental factors</p> Signup and view all the answers

    What is the characteristic of slime layer in bacteria?

    <p>It is a protein-linked and lipid-linked carbohydrate structure</p> Signup and view all the answers

    What is the antigenic property of flagellin protein?

    <p>H antigen</p> Signup and view all the answers

    What is the function of normal fimbria in bacteria?

    <p>To allow bacterial colonization on a surface via adhesion</p> Signup and view all the answers

    What is the primary function of spores in bacteria?

    <p>To protect bacteria in non-ideal conditions</p> Signup and view all the answers

    Why are biological molecules in microorganisms not visible under a microscope?

    <p>They do not absorb light</p> Signup and view all the answers

    What is the primary purpose of Gram staining in microbiology?

    <p>To visualize bacteria under a microscope</p> Signup and view all the answers

    What is the characteristic of the bacterial surface formation known as a biofilm layer?

    <p>It is a protein-linked and lipid-linked carbohydrate structure</p> Signup and view all the answers

    What is the primary function of the cytoplasmic membrane?

    <p>To regulate the transport of molecules into the cell</p> Signup and view all the answers

    What is the role of septal mesosomes in bacterial cell division?

    <p>To form the plasma membrane during bacterial cell division</p> Signup and view all the answers

    What is the function of peptidoglycan in bacterial cell walls?

    <p>To maintain bacterial integrity</p> Signup and view all the answers

    What is the composition of the glycan chain in peptidoglycan?

    <p>Alternating residues of N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG)</p> Signup and view all the answers

    What is the function of lysozyme enzyme in animal secretions?

    <p>To protect against bacterial infections</p> Signup and view all the answers

    What is the target of antibacterial drugs such as penicillin and cephalosporins?

    <p>The peptidoglycan layer</p> Signup and view all the answers

    What is the function of lateral mesosomes in bacterial cells?

    <p>To regulate plasmid multiplication and spore formation</p> Signup and view all the answers

    What is the main component of the cell wall that provides structural support to bacterial cells?

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

    What is the primary function of PHB granules in bacteria?

    <p>To serve as a source of energy for protein synthesis</p> Signup and view all the answers

    What is the main difference between bacterial and eukaryotic ribosomes?

    <p>The size of the subunits</p> Signup and view all the answers

    What is the primary function of plasmids in bacteria?

    <p>To provide a genetic advantage</p> Signup and view all the answers

    What is the main difference between transposons and plasmids?

    <p>The ability to independently multiply</p> Signup and view all the answers

    What is the composition of the cytoplasmic membrane in bacteria?

    <p>Phospholipids, proteins, and carbohydrates in small amounts</p> Signup and view all the answers

    What is the function of the cytoplasmic membrane in prokaryotic cells?

    <p>To surround the cell cytoplasm</p> Signup and view all the answers

    Why are most bacteria unable to synthesize sterol?

    <p>Because they are prokaryotic cells</p> Signup and view all the answers

    What is the term for the appearance of the cytoplasmic membrane?

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

    Study Notes

    Bacterial Morphology

    • Bacteria can be classified based on their shape:
      • Bacilli: rod-shaped, 1-8 µm in length
        • Cocci: round, spherical, 0.6-1.5 µm in size
        • Spirilla: spiral-shaped, curved
        • Filamentous: very long, thin, filament-shaped bacteria (e.g., Actinomyces)
        • Pleomorphic: no characteristic shape (e.g., Mycoplasma)

    Bacterial Cell Structure

    • Nucleoid (nuclear material):
      • No nuclear membrane
      • 10% of cell content
      • Circular, double-stranded DNA
      • Bacterial chromosome length is 1 mm
    • Cytoplasm and cytoplasmic structures:
      • Transparent, colloidal system
      • Contains water, ions, metabolites, proteins, nucleic acids, and granules
      • Ribosomes (70s)
      • Plasmids and transposons
      • No mitochondria or chloroplasts; electron transport enzymes are in the cytoplasmic membrane
    • Granules:
      • Concentrated deposits of certain substances in the cytoplasm of certain bacteria
    • Penicillin-binding proteins (PBPs):
      • Found in the cell wall and essential for cell wall synthesis
      • Bind to penicillin and other β-lactam antibiotics
      • Inhibition of PBPs causes cell lysis
    • Teichoic acid:
      • Anionic glycopolymers found in the peptidoglycan layer
      • Gives rigidity to the cell wall
      • Made up of ribitol phosphate and glycerol phosphate
      • Not found in Gram-negative bacteria
    • Gram-positive and Gram-negative bacteria:
      • Differences in cell wall structure and composition
      • Gram-positive: thicker peptidoglycan layer, teichoic acid present
      • Gram-negative: thinner peptidoglycan layer, no teichoic acid

    Bacterial Surface Structures

    • Capsule or slime layer:
      • Glycocalyx: a thin, high molecular weight secretory substance
      • Composed of polysaccharide, polypeptide, or both
      • Functions: increases virulence, protects from phagocytosis, and protects from antibiotics and environmental factors
    • Flagella:
      • Locomotion organelle in bacteria
      • Proteinaceous appendages protruding from the cell body
      • Structure contains helical-shaped proteins called flagellin
      • Antigenic properties
    • Fimbria (Pili):
      • Filamentous projections in Gram-negative bacteria
      • Thinner, shorter than flagella, without folding
      • Made up of simple protein units called pilin
      • Divided into two types: normal and sex fimbria
    • Spores (Endospores):
      • Resistant to physical and chemical environmental factors
      • Formed when environmental nutrients are scarce
      • Function: protect bacteria in non-ideal conditions

    Bacterial Staining Techniques

    • Gram staining technique:
      • Introduced by Hans Christian Gram in 1884
      • Selective permeability and transport of various molecules into the cell
      • Used to differentiate between Gram-positive and Gram-negative bacteria

    Functions of Cytoplasmic Membrane

    • Invaginations in the plasma membrane towards the cytoplasm
    • Two types: septal mesosomes and lateral mesosomes
    • Functions: formation of plasma membrane during bacterial cell division, plasmid multiplication, and spore formation

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    Bacterial Morphology and Cell Structure PDF

    Description

    This quiz covers the basics of bacterial cellular morphology, including shapes and sizes of bacteria cells. It's designed for students of pharmaceutical microbiology.

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