selective breeding, genetic engineering and cloning

• Why are organisms bred selectively?

  To produce more meat or milk

  Produce disease resistant crop

  Produce dogs that are nice

  Produce decorative plants with unusual colours and flowers
• Give the basic process of selective breeding

  Take organisms with desired traits

  Breed them together

  Select the best offspring and breed them together

  Continue this over several generations until trait is very strong and all offspring will have the trait
• What is the main drawback of selective breeding?


  reduction in the gene pool
• What does reduction in gene pool mean?

  It means it is less diverse, and less able to survive in survival of the fittest
• What are the drawbacks of reduction in gene pool (inbreeding)

  health problems

  genetic defects

  less chance of resistance to disease
• Give an example of an organism that suffers from inbreeding and what health problem they have

  pugs - breathing problems
• Genetic engineering transfers genes between organisms
• Give the process of genetic engineering

  Useful gene is isolated from an organisms genome

  useful gene is inserted into a vector using enzymes

  (The vector is usually a virus or bacterial plasmid)

  Vector introduced to target organism

  useful gene inserted into it's cells

  (this process is sometimes carried out when organism is at egg stage)
• Give 3 uses of genetic engineering

  Bacteria to produce insulin

  Genetically modified crops

  Researching their use in genetic diseases
• Genetic engineering is very controversial
• Give a reason why people don't like GM stuff

  don't know long lasting effects
• Give cons of GM crops

  reduce farmland diversity

  don't know long lasting effects

  May get out into environment and cause issues
• Give pros of GM crops

  increased yield

  'golden rice' - can contain more nutrients
• Plants can be clones from tissue culture and from cuttings
• Explain cloning from tissue culture

  A few plant cells are put in a growth medium with hormones and they grow into new plants
• Give pros of tissue culture

  very quick

  very little space needed

  grown all year

  preserve rare plants
• Explain cloning from cuttings

  Gardeners can take cuttings from a parent plant and plant it to produce clones
• Give pros of cuttings

  quick

  cheap

  simpler
• You can make animal clones using embryo transplants
• Explain embryo transplants

  Sperm cells taken from best animal

  egg cell taken from other best animal

  artificially fertilise egg using sperm

  embryo develops and splits many times before any cell specialisation

  cloned embryos can be implanted into other animals

  hundreds of ideal offspring produced
• Explain adult cell cloning

  remove nucleus from unfertilised egg cell

  take nucleus from an adult body cell

  insert nucleus into egg cell

  stimulate egg cell with shock so it divides

  When embryo is a ball of cells, it is implanted into womb of female
• State issues surrounding cloning

  Reduced gene pool (inbreeding)

  lead to health problems

  the future of cloning may involve children (ethical issues)
• State pros of cloning

  greater understanding of embryo development

  treatment of some disorders