6.2.1 - biotechnology and cloning

• Natural clones of plants can be produced by vegetative propagation
• vegetative propagation is when part of a plant is separated then develops into a new plant genetically identical to the original.
• for cloning, a plant cutting is when the stem is cut between the leaf and the nodes. The cutting is then replanted and allowed to grow, sometimes with the use of plant hormones.
• to produce artificial clones of plants we can either use

  tissue culture

  micropropagation
• tissue culture is when the sample is placed on various nutrient containing mediums to encourage cell division and shoot growth
• micropropagation is when material produced from tissue culture is rapidly multiplied to produce large numbers of plants.
• + of using plant cloning in agriculture is that large numbers of plants can be produced regardless of weather conditions.
• negative of using plant cloning in agriculture is that it reduces genetic variation, making them more susceptible to disease.
• natural cloning in animals is monozygotic twins.

  where the embryo splits during development to produce two genetically identical individuals.
• We can produce artificial clones of animals by either

  embryo splitting

  somatic cell nuclear transfer
• somatic cell nuclear transfer is when differentiated cells from parent are fused with an enucleated egg cell. the cell develops into an embryo and can be implanted into a womb.
• embryo splitting is the process of splitting an embryo into two embryos to produce two clones.
• + of cloning in animals is that it can preserve endangered species. and that it is a quick process suited to the growing population of earth.
• negatives of cloning in animals is that is gives cells a low genetic diversity. and cloned animals often suffer from health problems and genetic disorders.
• Microorganisms are suited for use in biotechnological processes because they have rapid growth in a variety of environmental conditions. they can be genetically engineered and it reduces the use of chemicals so is beneficial to the environment.
• microorganisms are used in biotech processes:

  • Making food - baking, brewing, yoghurt, cheese
  • medicine - penicillin, insulin
  • Environmental - removing pollution. Bioremediation.
• + of using microorganisms to produce food:

  • Production rate easily varied
  • not dependent on climate
  • long lasting
  • uses waste products
• disadvantages of using microorganisms to produce food:

  • lack of flavour
  • proteins must be isolated and purified
  • contains different amino acids to animal proteins
• aseptic techniques should be used to culture microorganisms.
• aseptic techniques are when everything is kept completely sterile so that no unwanted microorganisms are present in the culture.
• the three steps of growing microorganisms are:

  1. sterilisation - using aseptic techniques
  2. inoculation - microorganism introduced to agar
  3. incubation - placed in warm environment for 24-48 hours to grow
• the two types of fermentation are

  batch fermentation

  continuous fermentation
• Batch fermentation is in a closed environment. Maintains the culture in the stationary phase - then left to death phase. Whole batch is removed and sterilised so a new batch can be added.
• continuous fermentation is when the products are continually removed so maintains culture in exponential phase.
• Batch fermentation favours secondary metabolites.
• continuous fermentation favours primary metabolites.
• Growth conditions are manipulated inside fermenter to maximise yield by:

  • temperature maintained at optimum
  • sufficient nutrient supply
  • aerobic conditions to prevent products of anaerobic respiration
  • ph kept constant to maximise enzyme activity
• growth curve of microorganisms in a closed culture has 4 phases:

  1. lag phase = cells increase in size and take in nutrients. constant population.
  2. exponential phase = cells divide. population increases exponentially.
  3. stationary phase = nutrient levels decrease, slowing growth rate. population stabilises.
  4. death phase = population declines as the cells start to die.
• Formula for bacterial growth

  N = N0 x 2^n

  N = number of bacteria in population

  N0 = initial number of bacteria in population

  n = number of divisions
• An immobilised enzyme is an enzyme attached to an inert material in order to restrict its movement and hold it in place during a reaction.
• Methods of immobilising enzymes are:

  1. bonding = binds with support Ionically ( adsorption ) or covalently
  2. entrapment = placed in a semipermeable material that allows diffusion of substrate and product
  3. membrane separation = partially permeable membrane separates enzyme from substrate
• some uses of immobilised enzymes are:

  • glucose to fructose conversion
  • semisynthetic penicillin production
  • lactose to glucose / galactose conversion
  • pure samples of amino acids
  • dextrins to glucose conversion
• + of immobilised enzymes

  product is not contaminated by enzyme so does not need to be purified

  enzymes can be reused

  enzymes are protected from harsh environment
• negatives of using immobilised enzyme:

  expensive

  reaction rate is slower as enzymes cannot move
• To produce clones from cuttings:

  Use a healthy shoot; cut stem at a slant between nodes; dip in rooting powder; place in soil and add water; to reduce transpiration cover with plastic bag.
• Grafting is joining the shoot of one plant to the growing root or stem of another plant
• Adv of cloNing:

  • clone seedless fruit
  • can have desired trait
  • quick growth
• dis adv of cloning:

  • low genetic diversity
  • unlikely to survive a disease
• Tissue culture is growing plants from a cell based medium
• mitosis and asexual reproduction produces natural clones