Genetic Modification

Early Forms of Genetic Manipulation

  • Selection: choosing organisms with favored traits and allowing them to reproduce.
  • Hybridization: breeding dissimilar organisms to produce hybrids.
  • Inbreeding: breeding similar or related organisms.
  • Mutation breeding: subjecting plant seeds to UV rays and growing the seeds.

Modern Techniques in Genetic Modification

  • Recombinant DNA
  • Genetically modifying plants
    • Gene gun
    • Micropropagation
  • Xenotransplantation

Recombinant DNA

  • Restriction Enzymes: enzymes that cut DNA at particular sequences.
  • DNA Ligase Enzyme: enzymes that join the cut ends of DNA molecules.
  • Plasmids: small circles of DNA found in bacteria

 

Inserting Foreign Genes

  1. Isolate a gene and cut it out with a restriction enzyme.
  2. Cut plasmids with the same restriction enzyme.
  3. Allow “sticky ends” to join.
  • Bacteriophage: viruses that infect bacteria
    • Can be used to insert foreign genes into bacteria

 

Applications of Genetic Engineering

  • Transgenic Bacteria: engineered biomolecules like insulin and other pharmaceutics can be harvested from them.
  • Transgenic Plants: crops are genetically engineered for higher yield, pesticide resistance, and producing their own fertilizer.
  • Transgenic Animals: used for farming, ranching, or genetic research.

Transgenic Bacteria

  • Involves fusion of foreign DNA fragments with bacteria to manufacture:
    • Human insulin
    • Enzymes for washing powders
    • Enzymes in the food industry
    • Human growth hormone
    • Bovine Somatotropin (BST)
    • Human vaccines

Transgenic Plants

  • Involves the insertion of foreign DNA into plants for the following reasons:
    • Higher yield
    • Pesticide resistance
    • Producing own fertilizer
    • Heat and drought tolerance
    • Salt tolerance
    • Better nutrient balance
  • Involves the insertion of foreign DNA into plants using the following:
    • Agrobacterium - soil bacteria that regularly insert plasmids into plant cells.
    • Gene Gun - fires a gene-coated gold pellet into plant cells.

Transformation

  • Involves fusion of foreign DNA fragments with “plasmids” of Agrobacterium.
    • Plasmid leaves bacteria and invades plant cells, inserting itself into its DNA.

Moral, Ethical, and Social Concerns

  • Moral concerns - “playing God” and the unforeseen consequences of these alterations.
  • Ethical concerns - contamination of “wild” plants and animals, development of superweeds.
  • Social concerns - genetically engineered seeds may not be available except for those who can afford them.