cloning and biotechnology

• mitosis - the division of the nucleus to create 2 identical copies of dna in identical cells
• clone - genetically identical organisms

  • asexual reproduction
  • +vs: quick allowing taking advantage of resources, do not have to find a mate, all offspring have genetic information
  • -vs: no genetic variety, susceptible to environmental changes, intraspecific competition high
• vegetative propagation - production of structures in an organism that develop into a fully differentiated new organism which is genetically identical to its parent eg root suckers (new stems grow from roots) and tubers (stems become swollen with nutrients)
• tissue culture - growing new organisms from undifferentiated callus tissue

  eg seed banks can store callus not seeds to aid long term survival
• explant - the meristem tissue taken from the shoot tip
• callus - a mass of undifferentiated cells
• biotechnology - the use of living organisms in industrial processes
• culture - a population of organisms grown under controlled conditions
• metabolism - all chemical reactions
• primary metabolite - substances produced in a closed culture needed for growth

  • if population not kept in closed culture, products collected in log phase
  • matches growth curve
• secondary metabolite - substances produced in a closed culture not needed for growth
• lag phase - when bacteria are not dividing and are acclimatising to new conditions
• stationary phase - no net change in cell numbers as death rate equals birth rate
• log phase - exponential increase in number of cells, doubling every generation time
• decline phase - when cell death exceeds cell division
• batch culture - when there are no new nutrients added or waste products removed
• continuous culture - when waste products are removed and nutrients are added throughout the process
• asepsis - free of microbes
• aseptic technique - sterilisation of equipment
• immobilisation - when enzymes are trapped so that they can be reused
• using natural clones - cuttings, sued to produce large quantities of genetically identical plants quickly

  1. cut stem between lead nodes
  2. dip into rooting powder containing auxin
  3. place into damp soil
  4. cover with plastic bag to prevent evaporation of water
• using natural clones - grafting, used to ensure vigorous growth via selected rootstock. Either with new plants or produce the same tree

  1. cut a scion from the desired plant
  2. insert into the stem of the rootstock, lining up the vascular tissue
  3. treat to prevent pathogens entering
  4. secure with tape
• problems with using natural clones

  • cannot reproduce large numbers of cloned plant quickly
  • some plants not suitable
  • takes up a lot of space
  • not guaranteed to work
• advantages tissue culture

  • large quantities of disease free plants
  • any time of year can be carried out
  • long term storage of plant tissue which can be easily modified
  • easier to transport between countries
  • useful for plants that are rare
  • offspring will display the same set of beneficial characteristics as the parent
  • new plants are uniform in phenotype therefore easier to harvest
• steps of micropropagation / tissue culture

  1. small tissue taken using the shoot tip, contains the meristem cells. This is the explant, meristem free from viral infections
  2. explants are sterilised to kill bacteria or fungi
  3. explant placed onto nutrient agar containing glucose, amino acids, phosphates and cytokinin
  4. cells in the tissue divide but do not differentiate forming a callus
  5. callus' are removed and divided and left to grow
  6. platelets are transferred to sterile compost and acclimatised
• disadvantages of artificial cloning

  • tissue culture is Labour intensive
  • can fail due to infection
  • genetic uniformity increases susceptibility to any new pest
  • no genetic variation
• reproductive cloning of animals - produces large numbers of genetically identical animals
• artificial embryo twinning - reproductive cloning of animals

  • sperm and egg cells are collected from high vale organisms
  • the eggs are fertilised in vitro to produce a 16 cell embryo
  • cells from the developing embryo can be separated out
  • these are implanted into surrogate mothers to produce genetically identical offspring
• somatic cell nuclear transfer - reproductive cloning of animals

  • a differentiated somatic cell from an adult is taken and its nucleus is placed in an egg cell that has been enucleated
  • electrofusion is used to combine them
  • the egg then starts dividing by mitosis forming an embryo
  • embryo removed and placed into surrogate
  • offspring contain genetic information from inserted nucleus
• non reproductive cloning of animals - the production of genetically identical cells. the cells are not used to produce a whole new organism
• therapeutic cloning

  • new tissues and organs can be grown as a replacement for people
  • skin can be grown in vitro to act as a graft over burns
  • cloned cells have been used to repair damage to the spinal cord
  • potential to grow a whole new organ to replace diseased ones
• advantages -artificial cloning in animals

  • high value organisms can be cloned
  • rare animals can be cloned preserving rare species
  • gm animals can be quickly reproduced
  • testing medical drugs on cloned cells and tissues would avoid using animals
• disadvantages - artificial cloning in animals

  • high value organisms are not necessarily produced with animal welfare in mind
  • excessive genetic uniformity makes it difficult to adapt and change
• aseptic techniques examples

  • wash hands
  • disinfect area
  • have a bunsen burner operating to create sterile air and prevent air borne microbes settling
  • pass the neck of a bottle through the flame to prevent bacteria entering
  • any glass or metal used should be passed through the flame
• sterilisation - nutrient agar is sterilised in a heat sterilisers to kill all living organisms
• inoculation - introducing the bacteria to the sterile medium

  streaking: wire loop transfers the bacteria to the agar

  seeding: same process as above

  spreading: glass spreader spreads the bacteria
• incubation - the Petri dish closed and incubated at 37 degrees
• why use microbes in biotechnology

  • no ethical issues
  • genes are not in pairs and therefore will not be masked
  • rapid reproduction rate
  • prokaryotes reproduce asexually therefore clones
  • produce proteins that can be harvested easily
• indirect food production

  • baking uses yeast which produces co2 from aerobic respiration which causes bread to rise
  • brewing uses yeast which produces ethanol from anaerobic respiration
  • cheese uses bacteria which feed on lactose in the milk and change the texture
  • yoghurt uses bacteria which is fermented cheese
• direct food production - single cell protein (quorn)

  • a mycoprotein
  • grown in large fermenters then compressed into a meat substitute