21. Biotechnology and genetic engineering

• Why are bacteria useful in biotech & genetic engineering:

  • bacteria have rapid reproduction rate
  • their ability to make complex molecules
  • lack of ethical concerns over their manipulation & growth
  • genetic code shared with all the other organisms
  • presence of plasmids
• Biofuel:

  • use plants to make sugar, which yeast then breaks down to make ethanol
  • this process also uses anaerobic respiration
  • liquid is separated from solids & any water is removed, leaving a concentrated solution of ethanol
• Pectinase in fruit juice:

  • fruit is chopped up to release more juice, but not all cells break open, leading to juice loss
  • pectinase enzyme is added to chopped fruit, which breaks down cell walls in fruit
  • result in more juice being produced, juice is clear instead of cloudy
• Bread making:

  • yeast will respire anaerobically
  • glucose in flour is the reactant that yeast uses to produce carbon dioxide & ethanol through anaerobic respiration
  • carbon dioxide produced by the yeast is caught in the dough, causing the bread to rise
  • ethanol evaporates in the hot temperature of baking
• Enzyme + washing powder:

  • stains on clothes are organic molecules like lipids, carbohydrates & proteins
  • biological washing powders contain enzymes similar to digestive enzyme produced in the alimentary canal that help break down large food molecules
  • quickly breaking down stains faster, at a lower temperature
• Lactase (lactose free milk):

  • the enzyme that breaks down lactose, people can stop making lactase naturally & therefore can't digest lactose
  • lactase made from yeast
  • lactase bound to surface of alginate beads
  • milk passed down beads
  • lactose is broken down into glucose & galatose
  • immobilised enzymes are reused

  
• Penicillin (fermenters):

  • produces by a fungus called penicillium
  • require proper temperature, pH, oxygen, nutrient supply & waste products
  • stainless steel fermentation vessel contains sugars & ammonium salts
  • use sugar for respiration & ammonium salts to make protein
  • then filtered to remove fungus & crystallised to make capsules
• Fermenter:

  • nutrients: sugars, amino acids or other nutrients for growth
  • probes: monitor conditions in order to maintain optimal pH, temperature & reactant & product concentrations
  • sterile air: gases for aerobic/anaerobic respiration
  • pressure release valve: can release for the build up of gases
  • water-filled jacket: absorbs excess heat from respiration & maintain a constant optimal temperature
  • motor & stirrer: so microorganisms don't sink to the bottom & even distribution of mixture
  • cleaning fermenter: prevents contamination
• Fermenter diagram:

  A) motor

  B) probes

  C) stirrer

  D) water-filled jacket

  E) sterile air

  F) nutrients

  G) pressure release valve

  
• Genetic modification - changing the genetic material of an organism by removing, changing or inserting individual genes (e.g):

  • insertion of human genes into bacteria to produce human insulin
  • insertion of gene into crop plants to confer resistance to herbicides
  • insertion of genes into crop plants to confer resistance to insect pests
  • insertion of genes into crop plants to provide additional vitamins
• Restriction enzyme - an enzyme that cuts DNA when it finds a particular sequence, leaving sticky ends
• Complementary sticky ends - a single stranded section of DNA at the end of a gene that can base-pair & recombine with another
• DNA ligase enzyme - a plasmid that contains gene that has been inserted
• Recombinant plasmid - an enzyme that joins strands of DNA together
• Process of genetic modification:

  1. isolate the DNA making up a human gene, using restriction enzyme, forming sticky ends
  2. cut the bacterial plasmid DNA with the same restriction enzyme, forming complementary sticky ends
  3. insert the human DNA into bacterial plasmid DNA using DNA ligase to form a recombinant plasmid
  4. insert the recombinant plasmid into bacteria
  5. multiply the bacteria containing recombinant plasmid
  6. bacteria express the human gene to make human protein/insulin
• Genetically modified crops:

  Advantages:

  • increase food production
  • less greenhouse emission
  • some can be modified to be bug resistant
  • grow faster
  • need less resources
  • increase nutritional value

  Disadvantages:

  • farmers having to buy seeds every year
  • bugs can also be modified into stronger bugs
  • consumers may not buy GMOs (long term health impact)
  • companies can control supply, use, price