6.2.1. Cloning and biotechnology

• Immobilised enzymes are formed by

  1. enclosing enzymes within a partially permeable membrane
  2. entrapment into a silica gel matrix
  3. cross-linked; covalent or ionic bonds between amino acids of the enzymes sometimes using glutaraldehyde
  4. attached to a carrier such as activated carbon or clay

  advantages

  • enzymes removed and recyled
  • less downstream processing and leads purer product
  • more stable, less likely to be denatured by pH or temp

  disadvantages

  • deduced activity, cant mix freely with substrate
  • initial cost of bioreactor to set up, cost of enzyme
  • complex, technical issues
• The process of cloning using cells

  1. a diploid somatic cell from the organism is defrosted and the nucleus is removed
  2. the donor egg is enucleated
  3. the somatic cell nucleus is inserted into the enucleated oocyte
  4. electrofusion of the host cell and new nucleus triggers mitosis
  5. the transformed egg divides in vitro
  6. the embryo develops into a mature egg, which is incubated
• methods of natural cloning

  • runners
  • suckers
  • stolons
  • tubers
  • rhizomes
  • bulbs

  contain meristematic tissue
• plants cloned as cells removed from meristem tissue in axial buds or soot tips. the tissue sample that is removed is called the explant. ethanol can be used to sterilise the plant tissue. hormones are used to stimulate mitosis, which produces a mass of cells called a callus
• clones are used in investigations to reduce genetic variation, control more variables so the validity is increased
• advantages of vegetative propagation

  • some crop plants can not reproduce sexually from seed
  • young seedlings less likely to survive
  • uniform/ predictable size/ shape/ quality/ yield
  • quicker than growing from seed/ sexual reproduction
  • easier to harvest
  • can be done any time of the year
• describe how to clone a plant by taking a cutting

  1. use a healthy shoot/ cut shoot from a healthy plant
  2. cut stem at a slant between nodes, increases the sa:v ratio for the xylem and phloem
  3. dip in rooting powder, with the plant hormone auxin
  4. place in soil/ compost and add water to reduce transpiration
  5. cover with a plastic/ remove some seeds
• You can take many clones from a single original parent plant by taking many explants so the calluses are subdivided and the meristems from the plantlets can be subdivided
• grafting is a form of vegetative propagation where a shoot is attached to the growing stem and root of another plant, cut at an angle to increase the surface area for adhesion
• advantages

  • cheap
  • quick growth compared to seeds
  • clone seedless fruit
  • clones have desired genetic make up for characteristic

  disadvantages

  • low genetic diversity/ monoculture so less likely to be able to adapt to changing selection pressures
• uses of immobilised enzymes

  • lactase not present so fresh milk passed over immobilised lactase
  • semi synthetic penicillin; counteracts abiotic resistance, immobilised penicillin acylase used
  • glucose derived from starchy foods, breaks down into dextrins then glucose using glucoamylase to sweeten and thicken food
  • glucose isomerase converts glucose to fructone as its sweeter
  • aninoacylase separates L and D isomers of amino acid, producing dietary supplements and animal/ human food
  • acrylonitrate to acrylamide using nitrilase for synthetic polymers
• micropropagation

  • requires more expensive equipment and skills/ staff, contamination by microorganisms during tissue culture, lowers the gene pool, undesirable characteristics passed on
  • it produces more clone offspring, desirable characteristics, reproduced in any season as environment controlled, less space required, quicker than seeds, reproduce seedless plants
• micropropagation method

  1. cut the plant materials into explants (e.g. leaf/ root/ bud)
  2. sterilise explanation using bleach/ alcohol
  3. place on agar containing glucose and amino acids
  4. a callus will form and change using auxin and cytokines
  5. sub divide callus and treat to induce the roots and chance hormone ratio
• natural clones

  • asexual reproduction of flatworms
  • starfish regenerating limbs
  • hydra on the side of body
• artificial twinning

  animal with desired trait given hormone treatment to release more eggs

  • fertilisation/ insemination
  • eggs flushed out
  • totipotent blastocysts split into several smaller zygotes in vitro
  • implanted into surrogate
• animal cloning

  advantages

  • desirable characteristics passed on
  • faster
  • avoid mating risks
  • infertile animals can be reproduced
  • preserve biodiversity with an increasing numbers of endangered species
  • cloned any time of year, no breeding season
  • develop new treatments for disease

  disadvantages

  • expensive
  • no genetic variability, more susceptible to selection pressures like disease
  • shorter/ less healthy life
  • success rate is poor
• biotechnology is the large scale commercial use of living organisms for human consumption

  • food production; beer and bread with yeast, cheese with lactobacillus, quoin with fusarium, yoghurt with lactobacillus
  • enzymes and chemicals for commercial use; pectinase (fruit juice) and calcium citrate using a. niger
  • drugs and pharmaceuticals; penicillin using penicillium and insulin using E.coli
  • bioremediation of waste products; oil spills
• why are microorganisms used?

  • they have a rapid life cycle
  • single cell protein is healthier with a lower fat content and can be made to taste like anything
  • grow on unwanted food
  • can be genetically engineered, no welfare issues
  • use low temperatures making it cheaper
  • separate products easily so cheaper

  disadvantages

  • aseptic conditions needed
  • if optimal conditions not met, toxins may be produced
  • single cell protein doesn’t have the same flavour and texture as real meat
  • concerns about GMO food and eating what’s grown on waste
  • seperation of microorganisms/ proteins from nutrient medium