Genetic Variation and its Control

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  • Created by: LBC0502
  • Created on: 08-06-14 15:35
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  • Genetic Variation and its Control
    • Variation
      • Genetic information is passed from parents to offspring by gametes.
      • Cell-Nucleus-Genes-DNA
      • Genes carry characteristics. Different genes control the development of characteristics e.g. eye colour, hair colour, height.
      • Humans have 23 pairs of chromosomes.
      • Variation: difference between individuals of the same species. This is due to genetic/environmental causes e.g. twins are identical at birth but change due to lifestyle: diet/exercise.
      • Sexual reproduction: sperm (male) fuses with egg (female) produces new individual, creating variation.
      • Asexual reproduction: no variation (unless its due to the environment), one parent needed, produces individuals genetically identical to the parents (clone) e.g. bacteria.
    • Cloning
      • Plants can produce asexually. Plants can be cloned by taking cuttings from the plant (leaves/stem), which are planted and grown.
      • It's a cheap and quick way to produce plants. These are grown is a damp atmosphere until roots develop.
      • Tissue culture: choose parent plant with certain characteristics, few cells are taken and put in beakers with nutrients/hormones. Plants will grow (plants must be aseptic or they will rot). The offspring are genetically identical.
      • Embryo transplant: Parents with desired characteristics are mated, embryo is remove before cells become specialised, split apart into several clumps. Then, the embryos are implanted into the uteruses of sheep who give birth to clones.
      • Adult/Fusion Cell Cloning: DNA from donor cell is inserted into an empty egg cell, an electric shock causes the egg to divide, containing the same genetic information as the donor. The embryo is implanted into the womb and produces a clone.
    • Genetic Modification
      • Crops have genes modified by adding new DNA to improve: crop yield, resistance to pests/herbicides, fast growth and to extend shelf-life.
      • Concerns: genes from GM crops are passed to non-GM crops, causing super-weeds, nectar of GM crops harm insects, effects of GM crops on human health.
      • Genetic Engineering: Transfer genes with desired characteristics to different species e.g. insulin normally produced by pancreas to control glucose levels but diabetics don't have enough insulin/need to inject it. Human insulin gene is put in bacteria to reproduce.
      • Use enzymes to cut out human insulin gene. Enzymes cut bacteria plasmid at join human gene. Plasmid is put back in bacteria to reproduce, which produces more insulin.
    • Genetic Engineering and Cloning
      • Cloning: produces genetic copes. Genes coped within the same species
      • Genetic Engineering: produces a unique set of genes which can be passed across species.
      • Pros for GM crops: can be mass produced, cheaper, reduces world hunger. Provides nutrients, improves nutrition in LEDCs. Maximum yields can grow anywhere. Less space needed, preserve habitats. Less use of chemicals e.g. pesticides.
      • Cons for GM crops: could cross with non-GM crops, have consequences. Worries about consuming GM crops and health problems. Expensive to sell GM crops. May affect insects (super bugs). Long term consequences are unknown, interferes with nature, increases allergies and use of pesticides.


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