2.6 + 2.7 - environmental and genetic control of metabolism

• Why are micro-organisms used for metabolism?

  • adaptability
  • ease of cultivation
  • speed of growth
• What are the 4 culture conditions?

  • sterility
  • temperature
  • oxygen concentration
  • pH
• How is sterility controlled in an industrial fermenter ?

  use of a filter
• How is temperature controlled in an industrial fermenter?

  probes and monitored by thermostat and water jacket
• How is oxygen concentration controlled in an industrial fermenter?

  aeration paddles
• How is pH controlled in an industrial fermenter?

  the addition of buffers
• What is the lag phase of microbe growth?

  enzymes are being induced to metabolise substrates
• What is the log phase in microbe growth ?

  the most rapid growth due to plentiful nutrients
• What is the stationary phase of microbe growth?

  production of toxic metabolites, death rate is equal to growth rate
• What is the death phase of microbe growth?

  the toxic accumulation of metabolites
• What is a viable cell count?

  counts only the living micro-organisms
• What is a total cell count?

  counts both viable and dead cells
• How is a viable cell count obtained?

  using a vital stain which picks up only dead cells
• Define mutagenesis?

  exposure to substances that increase the chance of random change to DNA bases
• give an example of a mutagenic agent?

  UV light, or in general, radiation
• What is a vector?

  a DNA molecule used to carry foreign genetic information into another cell
• Give 2 examples of vectors?

  • plasmids
  • artificial chromosomes
• What 2 enzymes are involved in recombinant DNA technology?

  • restriction endonuclease
  • ligase
• What is the function of restriction endonuclease?

  cuts open plasmids and specific genes out of chromosomes
• What is the function of ligase?

  seals genes into plasmid
• What is the function of restriction sites?

  contain target sequences of DNA where specific restriction endonucleases cut
• What is the function of regulatory sequences?

  control gene expression
• Function of origin of replication?

  allows self-replication of the plasmid/artificial chromosome
• Function of selectable markers?

  ensure that only micro-organisms that have taken up the vector grow in the presence of the selective agent
• When are complimentary sticky ends produced?

  when the same restriction endonuclease is used to cut open the plasmid and the gene from the chromosome
• labels

  A) lag phase

  B) log phase

  C) stationary phase

  D) death phase