Natural Selection 2- Revision

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  • Natural Selection and Genetic Modification
    • Classification
      • Classification- Organising Living Organisms into Groups
        • Living things are first divided into five groups called kingdoms
          • *Animals-- fish, mammals, reptiles etc.
          • *Fungi-- mushrooms and toadstools, yeasts
          • *Prokaryotes-- all single-celled organisms without a nucleus
          • *Protists-- eukaryotic single- celled organisms eg. algae
          • The kingdoms are then subdivided into smaller groups that have common features
            • King Philip Came Over For Good Spaghetti
              • Kingdom, Phylum, Class, Order, Family, Genus, Species
      • Classification System Changes Over Time
        • Using genetic analysis, Carl Woses (scientist) suggested that all organisms should be first divided into three large groups called domains. Archaea, Bacteria and Eukarya
          • 3) Eukarya-- This domain included a broad range of organisms including fungi, plants, animals and protists
          • 2) Bacteria-- This domain contains true bacteria
          • 1) Archaea-- Organisms in this domain look similar to bacteria but have differences in their genetic sequences. They were first found in extreme places eg. hot springs + salt lajkes
    • Selective Breeding
      • When humans artificially select the plants or animals that are going to breed so that the genes for particular characteristics remain in the population
        • eg. Animals that produce more meat or milk, crops with disease resistance or plants that produce bigger fruit
      • Pros
        • Agriculture- Genetic variation means some cattle will have better characteristics for producing meat than others
          • To improve meat yields, a farmer could select cows and bulls and breed them together. After doing this, the farmer would get cows with a very high meat yield
        • Medical Research- In several studies investigating the reasons behind alcoholism, rats have been bred  with either a strong or weak preference of alcohol.
          • This has allowed researchers to compare the different types of rates including different behavior types + the way their brains work
    • Genetic Engineering
      • Vectors Can be Used to Insert DNA into Other Organsims
        • 5) These cells now use the gene you inserted to make the protein you want
        • 4) The recombinant DNA is inserted into other cells eg. bacteris
        • 1) The DNA you want to insert is cut out with a restrictive enzyme. The vector DNA is then cut open using the same restriction enzyme
      • Pros
        • Agriculture- Crops can be genetically modified to be resistant to herbicides (chemicals that kill plants).
          • This mans farmers can spray their crops to kill weeds without affecting the crop itself
        • Medicine- Researchers have manged to transfer human genes that produce useful proteins into sheep and cows
      • Cons
        • It can be hard to predict what effect modifying its genome will have on the organism
          • Many genetically modified embryos don't survive + some genetically modified animals suffer from health problems later in life
        • Genetically transplanted genes might get out in the environment + Genetically modified crops could adversely affect food chains- or even human health


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