Lesson 6: Fresh Mounting

• What is the simplest method for examining microorganisms?

  Suspending them in a fluid
• What is the purpose of wet preparations in microbiology?

  To determine motility and observe cell shape
• What are the two types of preparations for examining microorganisms?

  • Hanging-drop
  • Simple wet mount
• What is the first step in preparing a bacterial suspension?

  Sterilize nutrient broth in a test tube
• What should be observed under the microscope when studying bacteria?

  Morphology and motility presence/absence
• What are the two types of cell movement in microorganisms?

  Swimming and gliding
• What do bacteria use for independent motility?


  Locomotory organs like flagella and pili
• What is Brownian movement in bacteria?


  Vibratory movement when locomotory organs are absent
• What are the types of flagella in bacteria?

  • Atrichous
  • Monotrichous
  • Lophotrichous
  • Amphitrichous
  • Peritrichous
• What type of bacteria are atrichous?

  Bacteria without flagella
• What characterizes lophotrichous bacteria?

  Multiple flagella at one polar end
• What is unique about amphitrichous bacteria?

  Flagella at both polar ends
• Which bacteria are peritrichous?

  Escherichia coli and Bacillus subtilis
• How do polar flagellated cells change direction?

  • Reversing flagellar rotation
  • Stopping to reorient
  • Moving forward by clockwise rotation
• How do peritrichous flagellated cells achieve forward motion?

  • Flagella form a bundle and rotate counterclockwise
  • Clockwise rotation causes tumbling
  • Return to counterclockwise leads to new direction
• What are pili and fimbriae used for in bacteria?

  • Sticking to surfaces
  • Thin protein tubes from cytoplasmic membrane
• What is the first step in preparing a hay infusion for protozoa observation?


  Boil a handful of hay
• How is the hay infusion incubated?

  With a cheesecloth lid for a week
• What should be done to observe protozoans on a glass slide?

  Use cotton threads to trap them
• What is the first step in preparing a yeast suspension?


  Mix glucose, lukewarm water, and yeast
• What should be observed under the microscope when studying yeast?

  Look for budding yeasts
• What is the first step in preparing a moist chamber for mold observation?

  Sprinkle substrate with water
• What should be observed under the microscope when studying molds?

  Complete structure of fungal species
• What are the components to look for in fungal observation?

  • Spores
  • Hyphae
  • Sporangia