Stages of normal growth curves

Question 1

What are the stages of the norml growth curve?

Answer 1

• Lag phase
  -exponential growth(log)
  -Stationary phase
  -Death Phase
  -VNC

Question 2

The lag phase is a “flat” period of growth due to:

Answer 2

Newly inoculated cells that require a period of adjustment, enlargement, and synthesis
Cells are not yet multiplying at their maximum rate

Question 3

Exponential growth (logarithmic or log) phase:

Answer 3

Growth increases geometrically
Will continue as long as cells have adequate nutrients and the environment is favorable

Question 4

Stationary growth phase:

Answer 4

Cell birth and cell death rates are equal
Cell division rate is slowing down
Caused by depleted nutrients and oxygen, plus excretion of organic acids and biochemical pollutants into the growth medium

Question 5

Death phase:

Answer 5

Cells begin to die at an exponential rate due to the buildup of wastes.
Speed with which death occurs depends on the resistance of the species and how toxic the conditions are.
Slower than the exponential growth phase

Question 6

Viable nonculturable state (VNC):

Answer 6

Many cells in a culture in the death phase stay alive but are dormant.

Question 7

a predicable pattern of a bacterial population growth in a closed system can be measured by:
Placing a tiny number of cells into a sterile liquid medium
Incubating the culture over a period of several hours
Sampling the broth at regular intervals
Plating each sample onto solid media
Counting the number of colonies present

Answer 7

growth curve

Question 8

Chemostat

Answer 8

Automatic growth chamber
Admits a steady stream of new nutrients
Siphons off used media and old bacterial cells
Stabilizes growth rate and cell number
Used in research and industrial applications