Micropara - Lec (Lesson 2)

• What is a bacterium?


  A single-celled organism without a true nucleus that belongs to the kingdom Prokaryote (Monera).
• What is normal flora?


  Nonpathogenic bacteria that live on the skin and mucous membranes of the human gastrointestinal tract.
• What is bacterial taxonomy?


  Classification of organisms into categories based on genotypic and phenotypic characteristics.
• What are the three principal forms of bacteria based on shape?

  • Spherical or Ovoid (e.g., Micrococci, diplococci, staphylococci, streptococci, sarcinae)
  • Rod-shaped (e.g., bacilli, coccobacilli, streptobacilli)
  • Spiral (e.g., spirilla, spirochaetes, vibrios)
• What is pathogenicity?


  The ability of a microbe to produce disease in a susceptible individual.
• What is virulence?


  The relative ability of microorganisms to cause disease, usually measured by the number of microorganisms necessary to cause infection in the host.
• What are adherence factors in bacteria?

  Pili and fimbriae that help bacteria attach to surfaces.
• What role do anti-phagocytic factors play in bacterial pathogenicity?

  They help bacteria avoid being engulfed by immune cells.
• How do bacteria typically reproduce?

  Through simple cell division.
• What factors significantly impact bacterial growth rate?

  Temperature, nutrition, and other environmental factors.
• What is a bacterial colony?


  • A group of bacteria growing in a specific place.
  • Consists of descendants of a single cell.
  • Varies in shape, size, color, texture, and type of margin.
• What is mutation in bacteria?


  Adaptation of bacteria in response to environmental changes, with limits to this adaptability.
• Which bacterial forms are incapable of movement?

  Ovoid or spherical cocci.
• What is the function of flagella in bacteria?

  They provide motility to certain bacteria.
• What are the food and oxygen requirements of heterotrophic bacteria?

  They require organic material as food.
• What are aerobes and anaerobes?

  Aerobes require oxygen for growth, while anaerobes do not.
• What is the optimum temperature for most pathogens?

  37°C (98.6°F).
• What is the role of enzymes produced by bacteria?

  They break down complex food molecules into simpler components.
• What are exotoxins and endotoxins?

  Exotoxins disrupt cell function or kill cells, while endotoxins stimulate cytokine production causing shock.
• What are the functions of capsules in bacteria?

  • Protection against drying
  • Blockade of bacteriophages
  • Antiphagocytic properties
  • Promotion of attachment to surfaces
  • Stability in suspension
• What is the composition of the bacterial cell wall?

  It consists of peptidoglycan, which includes glycan chains of alternating N-acetyl-d-glucosamine (NAG) and N-acetyl-d-muramic acid (NAM).
• What distinguishes gram-positive bacteria from gram-negative bacteria?

  • Gram-positive: Thick peptidoglycan layer and teichoic acids.
  • Gram-negative: Two distinct layers with a thinner peptidoglycan layer confined to the inner layer.
• What is the function of the cell membrane in bacteria?

  It serves as the site of energy synthesis and selective permeability.
• What are pili or fimbriae?


  Hair-like, proteinaceous structures that help bacteria adhere to host cells.
• What are endospores?


  Resting cells that are highly resistant to desiccation, heat, and chemical agents.
• What is the structure of flagella?

  It consists of a filament, hook, and basal granule.
• How can motility be demonstrated in bacteria?

  Through flagellar stain, hanging drop, or semi-solid media.
• What are metachromatic granules and their significance?

  • Serve as energy sources and food reserves (glycogen, lipids, polyphosphates).
  • Examples: Babes-Ernst granules in C. diphtheriae.
• What is the function of mesosomes in bacteria?

  They are important for DNA replication and cell division.
• What is the nucleoid in bacterial cells?

  The region where the DNA is generally confined, not surrounded by a nuclear membrane.
• What are the nutritional requirements of bacteria?

  • Phototropic: Uses light energy.
  • Chemotropic: Uses chemical compounds.
  • Autotrophs: Uses inorganic compounds.
  • Heterotrophs: Uses organic compounds.
• What are the oxygen requirements for obligate aerobes and anaerobes?

  Obligate aerobes require oxygen, while obligate anaerobes do not.
• What is the incubation temperature for most bacteria and viruses?

  35-37 °C.
• What are halophilic bacteria?


  Bacteria that require high salt concentration for growth.
• What is the incubation temperature for fungi?

  28-30 °C.
• What is the significance of capnophilic bacteria?

  They require 5-10% carbon dioxide for growth.
• What is the role of extremophiles?

  They can survive in unusual conditions, such as absence of oxygen and increased temperature.
• What is the incubation and time for aerobes?

  35-37 °C for 18-24 hours.
• What is the incubation and time for anaerobes?


  35-37 °C for 24-48 hours.
• what are subspecies?


  same species but differ phenotypically