Topic2:Cell Growth

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Topic2:Cell Growth
2012-01-18 23:22:59
exponential binary fission population density vs time growth

Cell Growth (prokaryotes mainly)
Show Answers:

  1. ´╗┐Name the six major organic elements used in cell growth.
    High Electronegativity O>N>S=C~H=P Low Electronegativity
  2. Name the four main phases of the bacterial population growth curve (In order of occurrence)
    • 1. Lag Phase
    • 2. Exponential Phase
    • 3. Stationary Phase
    • 4. Death Phase
  3. Explain the difference between cells in phase 2, and cells in phase 4 in terms of metabolism.
    Stage 2 cells have not undergone the metabolic adjustment that stage 4 cells have in order to survive in the stage 4 environment, which is more toxic due to dying cells.
  4. Write the equation for describing unhindered exponential growth.
    • Nt = No2n = No2t/g
    • Nt = Number of cells after n divisions
    • No = Number of cells in initial population
    • t = time allowed for growth
    • g = time taken to double
  5. Name the term for bacteria who prefer cold growth environments. (0 - 10 C)
  6. Name the term for bacteria who prefer moderate growth environments. (25 - 40 C)
  7. Name the term for bacteria who prefer hot growth environments. (45 - 80 C)
  8. Name the term for bacteria who prefer hot as shit growth environments. (80+ C)
    Hyper Thermophiles
  9. True or False:Water is an organic molecule.
    False. Despite being composed of two of the six major bioelements, water is not considered an organic molecule.
  10. Describe the growth characteristics and causes of Lag phase.
    • During Lag phase, the growth curve is nearly flat.
    • The organisms are not yet "acclimatized" to their new environment. They begin to make the adjustments needed to survive in their new environment, but it is this lapse, or "Lag," in their growth pattern that gives this phase its' name
  11. Describe the growth characteristics and causes of Exponential phase.
    • During Exponential phase, the growth curve bends upwards and ascends rapidly.
    • The organisms have adapted to their environment and are reproducing very quickly in the presence of a resource surplus.
  12. Describe the growth characteristics and causes of Stationary phase.
    • During Stationary phase, the growth curve flattens.
    • The organisms begin to die, and resources begin to grow thin, causing a decrease in reproduction rates and the growth curve to level off.
  13. Describe the growth characteristics, and causes, of Death phase.
    • During Death phase, the growth curve slopes downward.
    • The organisms begin to die more rapidly then they reproduce. The dead organisms release toxins into the environment, increasing the death rate even more. Only those organisms who can adapt to this more toxic environment can survive.