Genetic engineering

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  • Genetic Variation
    • Genetic information
      • A section of chromosome is called a gene, different genes control the development of different characterists
      • The nucleus of the cell contains chromosomes, these are made up of DNA
      • During sexual reproduction, genes are passed from parents to offspring in the gametes (sex cells). This s how certain characteristics are inherited
    • Variation
      • a combination of genetic and environmental factors eg weight
      • Variation may be due to the genes they have inherited (genetic factors)
      • The conditions in which they have developed (environmental factors)
    • Reproduction
      • Asexual reproduction
        • Doesn't produce any genetic variation at all, only one parent is needed
        • No mixing of genes, all offspring are genetically identical to the parent, variation can be due to environmental change
      • Sexual reproduction
        • Genes of egg and sperm are mixed together producing a new individual causing variation
        • Involves male and female gametes fusing called fertilisation
    • Cloning
      • Embryo transplant is when the cells from a developing animal embryo are split before they become specialised, the resulting embryos are then transplanted into host mothers, they are genetically identical to each other but not their parents.
      • Tissue culture is when a small group of cells are scraped from a plant and the cells are grown on nutrient algar containing nutrients and hormones, the offspring are then genetically identical to the parent plant
      • Adult cell cloning is when the nucleus is removed from an unfertilised egg cell, the nucleus from an adult skin cell is inserted into the empty cell and electric shock cause the egg cell to start dividing to form an embryo, it is then inserted into a host mother the offspring is genetically identical to the donor animal that the nucleus came from
    • Genetic modification
      • This involves transferring genetic material from one organism to another
      • Induvidual genes are cut out of the chromosones of an organism using special enzymes
        • The genes then transfer to the cells of other organism
      • Genes can be transferred to the cells of animals and plants at an early stage in their development so that they develop the desired characteristics
        • improved yield more food per plant
        • improved resistance to pests or herbicides
        • a longer shelf life
        • GM crop concerns
          • The uncertainty on the human health
          • The affect on populations of wild flowers and insects


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