genetic control of metabolism 7

• Two ways in which wild strains of micro-organisms can be improved

  • Mutagenesis
  • Recombinant DNA technology
• Mutagenesis

  Exposing micro-organisms to UV light and other forms of radiation or mutagenic chemicals resulting in mutations
• Some mutations may produce an improved strain of micro-organism
• Mutagenesis

  • Using radiation or UV to induce mutations
• Recombinant DNA technology

  Involves the use of recombinant plasmids and artificial chromosomes
• Vector

  A DNA molecule used to carry foreign genetic information into another cell
• Vectors used in recombinant DNA technology

  • Artificial chromosomes
  • Plasmids
• Recombinant DNA technology

  1. Restriction endonucleases cut open plasmids and leave sticky ends

  2. Complementary specific ends (sticky ends) are produced when the same restriction endonuclease is used to cut open the plasmid and the gene from the chromosome

  3. Ligase will seal the gene into the plasmid
• Components a plasmid or artificial chromosome must contain

  • Restriction sites
  • Regulatory sequences
  • Origin of replication
  • Selectable markers
• Restriction sites

  Contain target sequences of DNA where specific restriction endonucleases cut
• Regulatory sequences

  Control gene expression
• Origin of replication

  Allows for self-replication of the plasmid/artificial chromosome
• Selectable markers

  Such as antibiotic resistance genes protect the micro-organism from a selective agent (antibiotic) that would normally kill it or prevent it from growing
• Genes are often introduced to prevent the survival of the micro-organism in an external environment (if it escapes into the real world)
• Recombinant yeast cells may be used, as plant or animal recombinant DNA expressed in bacteria may result in polypeptides being incorrectly folded