(Unit 2.6) Environmental Control

• What are microorganisms?

  Very small unicellular organisms
• Which domains of life do microorganisms belong to?

  Eukaryotes, bacteria, and archaea
• Give an example of a eukaryotic microorganism.

  Algae or yeast
• Why are microorganisms important to us?

  They produce useful metabolites for industries
• What industries rely on microorganisms?

  Medicine, food, and waste management
• How are microorganisms used in medicine?

  To produce vaccines and antibiotics
• What is bioremediation?

  Using microorganisms to break down waste
• Why are microorganisms easy to culture?

  They reproduce quickly and require cheap substrates
• What is a growth medium?

  The substance microorganisms grow on
• What is agar?

  A gel made from seaweed
• What do microorganisms need from their growth medium?

  Nutrients to grow and survive
• What environmental factors must be controlled for microorganism growth?

  Temperature, oxygen levels, and pH
• Why is sterility important in microorganism growth?

  To prevent competing microorganisms from growing
• How is temperature controlled during microorganism growth?

  Using water jackets and thermostats
• What happens if the temperature is too high for microorganisms?

  Enzymes will denature and stop functioning
• Why are oxygen levels important for aerobic respiration?

  Oxygen is required to avoid fermentation
• What are the four phases of microorganism growth?

  Lag, log, stationary, and death phases
• What occurs during the lag phase of growth?

  Preparation for growth without real increase
• What characterizes the log phase of growth?

  Rapid growth due to plentiful nutrients
• What happens during the stationary phase?

  No real change in population due to nutrient depletion
• What is produced during the stationary phase that benefits microorganisms?

  Secondary metabolites like antibiotics
• What occurs in the death phase of growth?

  Microorganisms die due to toxic accumulation
• How is population growth typically plotted?

  Using semi-logarithmic scales for growth curves
• What are the two methods to count cells in a culture?

  Total cell count and viable cell count
• What does a total cell count include?

  All cells, both live and dead
• What is a viable cell count?

  Counting only living cells in a sample
• Why is a viable cell count useful?

  It indicates when the death phase occurs
• What is the significance of distinguishing between live and dead cells?

  To accurately assess population health