22

• Natural cloning


  Form of asexual reproduction where the offspring is genetically identical to the parent
• Plant cloning (natural)


  1. Body part is separated

  2. Develops into a new plant
• Plant cuttings


  • Simple cloning technique
  • Section of the stem is cut between the leaf and nodes
  • Encourage growth with rooting powder and hormones
• Animal cloning (natural)


  • Formation of twins by embryo splitting
• Artificial cloning


  Cloning of plants and animals through artificial means
• Plant cloning (artificial)


  1. Explant is taken from the shoot tip

  2. Placed on nutrient rich growth medium

  3. Cells divide by mitosis to form a callus

  4. Callus is then placed on growth medium with plant hormones to stimulate shoot growth

  5. Plantlet is then transferred to greenhouse to acclimatise
• Micropropagation


  1. Callus is produced

  2. Placed in nutrient rich medium

  3. Placed in medium containing growth regulators

  4. Plantlet is formed and then acclimatised
• Advantages of plant cloning

  • Large number of plants produced
  • Doesn't matter what season or weather
• Disadvantages of plant cloning

  • Lack of variation, genetically identical plants
  • Wouldn't respond well to disease or pathogen
  • Harder to grow than sowing seeds
• Animal cloning (artificial)


  1. Differentiated cell is taken from parent

  2. Fused with enucleated egg of another individual

  3. Cell divides and is implanted into surrogate mother
• Embryo splitting


  • Cells from a developing embryo are separated to produce two genetically identical organisms
• Advantages of animal cloning

  • Animals of human benefit can be cloned quickly
  • Preserve endangered species
• Disadvantages of animal cloning

  • Lack of genetic variation
  • Uncertainty about health and long-term welfare of animals
• Microorganisms


  • Easy to grow as they grow rapidly
  • Can be genetically engineered to produce desired products
  • Used in processes such as brewing, baking, cheese making, yogurt production, penicillin production, insulin production and bioremediation
• Pure culture


  Contains only a single microorganism
• Mixed culture


  Mix of different microorganism species
• Growth curve of microorganisms

  1. Lag phase: Microorganisms adjusting to environment, population remains constant

  2. Log phase: Population size grows exponentially

  3. Stationary phase: Population size reaches maximum due to decreasing nutrients and toxic substances

  4. Decline phase: Lack of nutrients and increase in toxic products causes death of organisms
• Batch fermentation


  1. Carried out in a closed fermenter

  2. Microorganisms and nutrients added and left to grow for a particular period

  3. No further nutrients added, products removed at end of period
• Continuous culture


  1. Takes place in an open fermenter

  2. Nutrients continuously added

  3. Products removed at a steady rate
• Advantages of continuous culture

  • Contamination of batch culture only loses a single batch, whereas in continuous culture it can lead to a huge amount of product lost
• Conditions for maximising product yield

  • Maintain optimum temperature
  • Sufficient nutrient supply
  • Maintain aerobic conditions
  • Maintain constant pH to ensure enzyme activity
• Contamination


  Unwanted microorganisms present in the medium, competing for nutrients and space, reducing product yield
• Enzyme immobilisation


  • Absorption: Enzymes bind to a support through hydrophobic and ionic interactions
  • Covalent bonding: Enzymes covalently bind to a support with the help of a cross linking agent
  • Entrapment: Enzymes trapped in a semi permeable material like gel beads
  • Membrane separation: Partially permeable membrane separates enzymes from substrate
• Immobilised enzymes


  • Glucose isomerase: Conversion of glucose to fructose
  • Penicillin acyclase: Formation of semi-synthetic penicillin
  • Lactase: Hydrolysis of lactose to glucose and galactose
  • Aminoacyclase: Production of pure samples of L-amino acids
• Counting bacterial colonies


  1. Serial dilution to produce a plate where individual colonies can be counted

  2. Count colonies to work out population per cm3
• 1. 0.1 cm3
• 1. 10^-5-500, 500 x 10^6
• 1. 10^-52, 52 x 10^4
• Indirect food production