Bacterial Classification Types
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Questions and Answers

What is the main characteristic of Gram-positive bacteria?

  • Thick peptidoglycan layer (correct)
  • Outer membrane with lipopolysaccharides
  • Thin peptidoglycan layer
  • No cell wall

    • Which type of bacteria obtains energy by consuming other organisms?

  • Heterotrophic (correct)
  • Autotrophic
  • Chemotrophic
  • Phototrophic

    • What is the function of the cell membrane?

  • Site of protein synthesis
  • Regulates transport and maintains cell environment (correct)
  • Stores genetic material
  • Provides shape and support to the cell

    • Which organelle is responsible for protein synthesis?

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

    What is the function of flagella?

    <p>Used for motility</p> Signup and view all the answers

    What is the main function of the capsule?

    <p>Helps evade host immune system</p> Signup and view all the answers

    What division does Escherichia coli belong to?

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

    What is the order of Escherichia coli in the Adansonian classification?

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

    What is the basis of genetic or molecular classification?

    <p>Homology of DNA base sequences</p> Signup and view all the answers

    What is the outermost layer of a bacterium composed of?

    <p>Cytoplasmic membrane and cell wall</p> Signup and view all the answers

    What is the function of slime layer protein?

    <p>All of the above</p> Signup and view all the answers

    What is the composition of slime layer?

    <p>Protein molecules with carbohydrates</p> Signup and view all the answers

    What is the role of fimbriae in bacteria?

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

    What is the term for all substances containing polysaccharides outside the cell wall?

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

    What kingdom do microorganisms belong to?

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

    What is the main difference between prokaryotes and eukaryotes?

    <p>Prokaryotes have a different type of cellular organization</p> Signup and view all the answers

    What is the function of bacterial classification?

    <p>To group microorganisms based on their characteristics</p> Signup and view all the answers

    Which type of classification is a type of hierarchical classification that represents a branching tree-like arrangement?

    <p>Phylogenetic classification</p> Signup and view all the answers

    What is a characteristic of archaebacteria?

    <p>They are closely related to eukaryotes</p> Signup and view all the answers

    What do bacteria lack, unlike blue green algae?

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

    What is the basis of bacterial classification?

    <p>Both phenotypic and genotypic similarities</p> Signup and view all the answers

    What is the name of the approach that is usually followed in bacterial classification?

    <p>Phylogenetic, Adansonian, and Genetic classifications</p> Signup and view all the answers

    Study Notes

    Bacterial Classification

    • Based on cell wall composition:
      • Gram-positive bacteria: thick peptidoglycan layer, no outer membrane
      • Gram-negative bacteria: thin peptidoglycan layer, outer membrane with lipopolysaccharides
    • Based on shape:
      • Spherical (cocci)
      • Rod-shaped (bacilli)
      • Spiral (spirilla)
      • Comma-shaped (vibrios)
    • Based on metabolism:
      • Phototrophic: use light energy
      • Chemotrophic: use chemical energy
      • Heterotrophic: obtain energy by consuming other organisms
    • Based on oxygen requirements:
      • Aerobic: require oxygen
      • Anaerobic: do not require oxygen
      • Facultative anaerobic: can grow with or without oxygen

    Bacterial Structure

    • Cell wall: provides shape, support, and protection
      • Peptidoglycan (murein): thick, rigid layer in Gram-positive bacteria
      • Outer membrane: thin, flexible layer in Gram-negative bacteria
    • Cell membrane: regulates transport, maintains cell environment
      • Phospholipid bilayer with embedded proteins
    • Cytoplasm: site of metabolic reactions
      • Gel-like substance with water, salts, and organic molecules
    • Nucleoid: region with genetic material
      • No true nucleus, genetic material is not membrane-bound
    • Ribosomes: site of protein synthesis
      • Small, spherical organelles found throughout cytoplasm
    • Flagella: used for motility
      • Long, whip-like structures composed of protein
    • Pili: used for adhesion and DNA transfer
      • Short, hair-like structures composed of protein
    • Capsule: protective layer outside cell wall
      • Polysaccharide or protein layer that helps evade host immune system

    Bacterial Classification

    • Bacteria classified based on cell wall composition, shape, metabolism, and oxygen requirements
    • Gram-positive bacteria: thick peptidoglycan layer, no outer membrane
    • Gram-negative bacteria: thin peptidoglycan layer, outer membrane with lipopolysaccharides

    Bacterial Shapes

    • Spherical (cocci)
    • Rod-shaped (bacilli)
    • Spiral (spirilla)
    • Comma-shaped (vibrios)

    Bacterial Metabolism

    • Phototrophic: use light energy
    • Chemotrophic: use chemical energy
    • Heterotrophic: obtain energy by consuming other organisms

    Oxygen Requirements

    • Aerobic: require oxygen
    • Anaerobic: do not require oxygen
    • Facultative anaerobic: can grow with or without oxygen

    Bacterial Structure

    Cell Wall

    • Provides shape, support, and protection
    • Peptidoglycan (murein): thick, rigid layer in Gram-positive bacteria
    • Outer membrane: thin, flexible layer in Gram-negative bacteria

    Cell Membrane

    • Regulates transport, maintains cell environment
    • Phospholipid bilayer with embedded proteins

    Cytoplasm

    • Site of metabolic reactions
    • Gel-like substance with water, salts, and organic molecules

    Nucleoid

    • Region with genetic material
    • No true nucleus, genetic material is not membrane-bound

    Ribosomes

    • Site of protein synthesis
    • Small, spherical organelles found throughout cytoplasm

    Flagella

    • Used for motility
    • Long, whip-like structures composed of protein

    Pili

    • Used for adhesion and DNA transfer
    • Short, hair-like structures composed of protein

    Capsule

    • Protective layer outside cell wall
    • Polysaccharide or protein layer that helps evade host immune system

    Classification of Living Organisms

    • All living beings can be classified into three kingdoms: Plant, Animal, and Protista.
    • Microorganisms are a heterogeneous group of several distinct living structures of microscopic size, classified under the kingdom Protista.

    Types of Microorganisms

    • Prokaryotes: Bacteria and blue-green algae, unicellular, capable of performing essential life processes, lacking chlorophyll.
    • Eukaryotes: Fungi, algae (except blue-green algae), protozoa, and slime moulds.
    • Archaebacteria: Closely related to eukaryotes, do not include human pathogens.

    Bacterial Classification

    • Bacterial classification: arrangement of organisms into taxonomic groups based on phenotypic and genotypic similarities and differences.
    • Three main approaches: phylogenetic, Adansonian, and genetic classifications.

    Phylogenetic Classification

    • Hierarchical classification representing a branching tree-like arrangement.
    • Example: E. coli classification:
      • Division: Protophyta
      • Class: Schizomycetes
      • Order: Eubacteriales
      • Family: Enterobacteriaceae
      • Tribe: Escherichiae
      • Genus: Escherichia
      • Species: coli

    Adansonian Classification

    • Based on all characteristics expressed at the time of study, giving equal weight to all measurable features.

    Genetic Classification

    • Based on homology of DNA base sequences of microorganisms, using DNA hybridization or recombination methods.

    Bacterial Anatomy

    • Outermost layer consists of a rigid cell wall and cytoplasmic membrane.
    • Protoplasm includes cytoplasm, cytoplasmic inclusions (ribosomes, mesosomes, granules, vacuoles, and nuclear body).
    • Some bacteria have a viscid layer (slime layer or capsule) and filamentous appendages (flagella and fimbriae).

    Slime Layer

    • Structured paracrystalline protein layer composed of a single kind of protein molecule, sometimes with carbohydrates attached.
    • Resistant to proteolytic enzymes and protein-denaturing agents, protects the cell from wall-degrading enzymes and bacteriophages.

    Capsule

    • Gelatinous secretion outside the cell wall.

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    Description

    This quiz explores the different ways to classify bacteria, including cell wall composition, shape, and metabolism. Test your knowledge of gram-positive and gram-negative bacteria, as well as phototrophic, chemotrophic, and heterotrophic bacteria.

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