Bacteria Classification and Morphology
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Questions and Answers

Which of the following is NOT a characteristic of endospores?

  • Being formed inside a parent cell
  • Remaining dormant for years
  • Being formed by bacteria like Streptococcus (correct)
  • Requiring water to germinate

    • What is the function of the capsule in bacteria?

  • To increase the movement of waste out of the cell
  • To protect the cell from desiccation (correct)
  • To increase the movement of nutrients into the cell
  • To increase the cell's viscosity

    • Which of the following is NOT a part of the cell envelope?

  • Cytoplasm (correct)
  • Outer membrane
  • Periplasmic space
  • Cell wall

    • What is the function of autolytic enzymes in spore germination?

    <p>To destroy the cortex</p> Signup and view all the answers

    Which of the following bacteria is known for forming terminal spores?

    <p>Clostridium spp</p> Signup and view all the answers

    What type of organisms are bacteria?

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

    What is the purpose of negative staining using India ink?

    <p>To observe the capsule</p> Signup and view all the answers

    What is the main difference between bacterial and animal cells?

    <p>Animal cells have a nucleus while bacterial cells do not</p> Signup and view all the answers

    What is the difference between a capsule and a slime layer?

    <p>A capsule is attached, while a slime layer is loose</p> Signup and view all the answers

    What is the function of plasmids in a bacterial cell?

    <p>To replicate independently of the cell's chromosomal DNA</p> Signup and view all the answers

    What is the composition of bacterial cell walls?

    <p>Peptidoglycan (polymer of NAG and NAM cross-linked with polypeptide chain)</p> Signup and view all the answers

    What is the effect of the capsule on the appearance of bacterial colonies?

    <p>Smooth colonies are produced by capsulated bacteria, while rough colonies are produced by non-capsulated bacteria</p> Signup and view all the answers

    What is the shape of bacterial DNA?

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

    What is the function of ribosomes in a bacterial cell?

    <p>To synthesize proteins</p> Signup and view all the answers

    What is the process by which bacteria divide?

    <p>Binary fission</p> Signup and view all the answers

    What is the term for the region in a bacterial cell where the DNA is found?

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

    What is the primary purpose of autoclaving in bacterial cultures?

    <p>To ensure bacterial survival</p> Signup and view all the answers

    What is the approximate percentage of dry weight of the cell that the cytoplasmic membrane makes up?

    <p>10% of dry weight</p> Signup and view all the answers

    What is the purpose of septal mesosomes?

    <p>To initiate septum formation</p> Signup and view all the answers

    What is the function of the cytoplasmic membrane in terms of electron transport?

    <p>To facilitate electron transport similar to mitochondria</p> Signup and view all the answers

    What is the shape of bacteria known as Bacilli?

    <p>Rod shaped</p> Signup and view all the answers

    What is the term for the process of binary fission in bacteria?

    <p>Binary fission</p> Signup and view all the answers

    What is the size range of bacteria of medical importance?

    <p>0.2-1.5 µm in diameter</p> Signup and view all the answers

    What is the purpose of mesosomes in bacterial cells?

    <p>To facilitate replication and sharing of DNA to daughter cells</p> Signup and view all the answers

    What is the characteristic of bacterial chromosomes?

    <p>It is single, circular, and double-stranded</p> Signup and view all the answers

    What is the purpose of Gram stain?

    <p>To differentiate between Gram positive and Gram negative bacteria</p> Signup and view all the answers

    What is the characteristic of Gram positive bacteria?

    <p>They retain the crystal violet stain</p> Signup and view all the answers

    What is the characteristic of intra-cytoplasmic inclusions?

    <p>They are made up of either glycogen or starch</p> Signup and view all the answers

    How do Gram negative bacteria differ from Gram positive bacteria?

    <p>They have an outer membrane</p> Signup and view all the answers

    Who developed the Gram stain technique?

    <p>Hans Christian Gram</p> Signup and view all the answers

    Which of the following Gram-negative bacteria is a potential pathogen in the oropharynx?

    <p>Neisseria meningitidis</p> Signup and view all the answers

    Which of the following bacteria is known for causing infection in immunocompromised patients?

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

    Which of the following Gram-negative rods are oxidase positive?

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

    What is the mechanism of action of C. botulinum's toxin?

    <p>Inhibiting the release of ACH</p> Signup and view all the answers

    Which of the following bacteria is an anaerobe that resists penicillin?

    <p>Bacteroides fragilis</p> Signup and view all the answers

    Which of the following is a sequelae of C. tetani?

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

    Which of the following Gram-negative bacteria is a fastidious GNR?

    <p>Bordetella pertussis</p> Signup and view all the answers

    Which of the following is NOT a characteristic of C. tetani?

    <p>Inhibits the release of ACH</p> Signup and view all the answers

    Study Notes

    Bacteria Classification

    • Bacteria are unicellular, microscopic, free-living microorganisms that can perform essential life functions.
    • They have both DNA and RNA, lack chlorophyll, and can be found in various environments, including water, food, soil, and air.
    • Bacteria can survive in extreme conditions, such as pH, oxygen, temperature, and atmospheric temperature.

    Morphology of Bacteria

    • Bacteria have a prokaryotic cell structure, meaning they lack a nucleus and organelles bound in membranes.
    • They have a single circular chromosome, no histones associated with DNA, and a cell wall made of peptidoglycan.
    • They have smaller ribosomes and divide by binary fission.

    Bacterial Cell Structure

    • The nucleus is also called the nucleoid, nuclear body, or nuclear region.
    • DNA is a single circular chromosome that is coiled up and floats in the cytoplasm.
    • The cytoplasm is a watery, soft gel that contains organic and inorganic solutes, vitamins, coenzymes, ribosomes, and a network of fine fibrils.
    • Plasmids are small, circular, double-stranded DNA molecules that can replicate independently.

    Gram Staining Technique

    • Gram staining was developed by Hans Christian Gram in 1884.
    • It differentiates Gram-positive bacteria, which remain colored after staining, from Gram-negative bacteria, which do not retain the dye.
    • Gram-positive bacteria are more susceptible to antibiotics due to the lack of an outer membrane.
    • Gram-negative bacteria contain an outer membrane, making them less susceptible to antibiotics.

    Gram-Positive Bacteria

    • Examples of Gram-positive bacteria include Bacillus, Clostridia, and Actinomycetes.

    Gram-Negative Bacteria

    • Examples of Gram-negative bacteria include Neisseria gonorrhoeae, Neisseria meningitidis, Enteric bacteria, Pseudomonas, and Bacteroides fragilis.
    • Gram-negative bacteria can be further divided into fastidious GNRs, anaerobic GNRs, and oxidase-positive or -negative GNRs.

    Bacterial Cell Envelope

    • The cell envelope refers to all the layers from the cell membrane outward, including the cell wall, periplasmic space, outer membrane, and capsule.
    • All free-living bacteria have a cell wall, and the periplasmic space and outer membrane are found in Gram-negative bacteria.

    Binary Fission

    • Binary fission is a process of cell division where a single DNA molecule replicates, attaches to different parts of the cell membrane, and then divides into two identical cells.

    Shapes of Bacteria

    • Bacteria can have various shapes, including cocci (spherical or oval), bacilli (rod-shaped), vibros (comma-shaped), spirilla (rigid spiral forms), and spirochetes (flexible spiral forms).

    Spore Germination

    • Spore germination is the process by which a dormant spore becomes active and forms a vegetative cell.
    • Bacteria with spores include Bacillus and Clostridia.

    Capsule

    • The capsule is a layer of extracellular polymeric substances surrounding the bacterial cell.
    • It can protect the cell from desiccation, anti-bacterial agents, and phages, and maintain cell viscosity.
    • The capsule can be stained using negative staining with India ink.

    Intra-Cytoplasmic Inclusions

    • Intra-cytoplasmic inclusions are rough granules that can be made up of glycogen or starch.
    • They can be stained with polychrome methylene blue or toluidine blue.

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    Learn about the characteristics and morphology of bacteria, including their cell structure and ability to survive in extreme conditions.

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