Microbiology

• Bacteria can obtain energy through various metabolic pathways, such as aerobic respiration, anaerobic respiration, and fermentation.
• What microscope has the best resolution?

  Electron
• Color with the largest/longest resolution?

  Violet - Ultra violet
• Color with the smallest and shortest resolution?

  Red - Lowest energy
• Why do we heat fix specimen?

  • Adheres to slide
  • Kills bacteria
  • Denatures proteins allowing bacteria to take up stain
• What differentiates bacteria from one another when it comes to gram + and gram -?

  Cell wall
• Which are bigger? Eukaryotes or Prokaryotes?

  Eukaryotes - They’re bigger and absorb more light
• Motility of Eukaryotes

  • Flagella - Whiplike (Back & forth)
  • Cilia
  • Pseudopods
• Motility of Prokaryotes

  Flagella - Erratic; Rotates clockwise & counter clockwise
• What is Brownian Motion?

  Vibrating false movements - False motion
• Why are organisms difficult to observe?

  Living organisms have approx. water context of 70% and their refractive index is similar to an anion.
• The purpose of simple stain 


  To increase the refractive index to help identify organisms
• The principles of simple stain (Bacteria vs slide)

  • Bacteria has a slight - charge
  • Slide/ environment has a slight + charge
• Stains are _

  Salts
• What large molecule has a + charge & gives color?

  Chromophore
• Name of sphere shaped bacteria?

  Cocci
• Names of Bacili shaped bacteria?

  Rods
• Differential stain - Gram + vs Gram -

  Gram + has a thick peptoglycan

  Gram - have a thin peptoglycan
• What stain is based on the properties of the cell wall?

  Differential stain
• What is parfoclization?

  When lens are in focus with minor adjustments; fine adjustment
• Gram Stain Procedure - Initial stain

  Crystal violet is applied to slide for 1 min then washed to stain bacteria
• Gram Stain Procedure (2) - Mordant

  Iodine is applied to slide after initial stain; binds to stain to make diff. for stain to be removed
• Gram Stain Procedure (3) - Decolonizes + Differential step


  Alcohol is applied to stain for 5 sec; It tries to remove the stain by destroying the IPS for counter stain.
• Gram Stain Procedure (4) - Counter stain


  Safranin is applied to slide for a minute to stain living organisms
• In a reticule what does each tick represent? —————-

  Each tick represents 25 micrometers
• Fermentation removes what from bacteria?

  Oxygen
• On the microscope, what lens views the specimen and can change its magnification?


  Objective lens
• What is R.O.D.A.C?

  • Replicate
  • organism
  • detection
  • counting
• The purpose of using plate counts (swab testing)?


  To determine viable microorganisms
• On a MacConkey plate what does it mean when you see no growth?

  It is gram +
• Why are live organisms difficult to see?

  They have a similar refractive index and are about 70% water
• Bacteria have a slight _ charge

  Negative
• What media is mannitol salt?

  Selective and differential
• What is applied to the organism during the differential step in the gram stain?

  Iodine
• Why use oil on 100x lens?

  Oil allows the objective lens to collect more light to form an image; Due to its refractive index
• 3 ways to adjust light on the microscope?

  1. Rheostat 2. Light source 3. Condenser
• What type of media is blood agar?

  Differential
• When you see a plate of mannitol salt with no growth then it has no _

  Halodures
• During a gram stain procedure what can go wrong? (include charges)

  • Dead bacteria : Gram -
  • Too much bacteria : Gram +
  • Too much alcohol : gram -
  • Too little alcohol : gram +
• What is gram stain?

  A way to identify type of infectious bacteria