microbio midterm

• culture medium


  a nutrient material prepared for the growth of microbes in the lab.
• Methods of Preserving Bacterial Cultures

  Refrigeration

  Deep Freezing

  Lyophilization
• Refrigeration


  to preserve the culture for long period of time.
• Deep freezing


  temperature quickly lowered to -50C to -95C.
• Lyophilization


  microbes are quickly frozen while the water content is removed at the same time.
• Certain trace elements ex.

  zinc, copper, iron, sodium, chloride, potassium, calcium.
• Broth


  media can be used in a liquid form.
• Slant


  if the agar in a test tube is solidified while the tube is tilted.
• Agar deep


  if the tube is left vertical while the agar sets.
• Liquid media


  these are available for use in test-tubes, bottles or flasks.
• Semi-solid agar


  reducing the amount of agar to 0.2-0.5% renders a medium semi-solid.
• Solid media

  any liquid form can be rendered by the addition of certain solidifying agents.
• Classification of Media

  simple

  complex

  synthetic
• Simple medium


  peptone water, nutrient agar can support most non-fastidious bacteria.
• Complex medium


  which the exact chemical constitution of the medium is not known of have ingredients whose exact components are difficult to estimate.
• Synthetic medium


  which teh exact chemical composition is known and specially prepared for research purposes.
• Binary fission


  chromosomes of the bacteria replicates after which the cells divides.
• Conjugation


  how the bacteria exchanges genetic information.
• Main Groups of Bacteria

  cocci

  bacilli

  spiral forms
• cocci


  look like little berries under microscope.
• Bacilli


  shaped like rods or cylinders.
• Spiral forms


  curved rods or spirals.
• 3 Spiral Forms

  vibrio

  spirilla

  spirochetes
• Smear


  usually begins by spreading a thin film of the specimen over a slide.
• Staining


  a process where bacteria cells are so small that they must be colored with some dyes to be studied more closely.
• Differential staining


  more complex staining method.
• Gram-staining method


  this is the most important staining technique in microbiology.
• Dr. Christian Gram


  gram staing was developed in 1884 by.
• gram-positive


  bacteria from which the blue color of the stain-iodine-bacterial cell complex cannot be removed.
• gram-negative


  those from which it can be removed and which are stained with the counterstain.
• acidic dye


  not attracted to the bacteria and color the background, leaving the bacteria unstained.
• basic dye


  attracted to the outside of the bacterial cells, which are usually slightly negative in charged.
• albert's stain


  using toluidine blue and malachite green.
• neisser's stain


  using methylene blue.
• binary fission


  the bacterial cells doubles in size and replicates its chromosomes.
• budding


  few bacteria and some eukaryotes may also replicates.
• lag phase


  the number of cells doesnt increase.
• log phase


  cell numbers increase exponentially.
• stationary phase


  the number of cells doesnt increase but changes im cells occur.
• death phase


  cells begin to die out.