Genetics and Evolution

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  • Genetics and Evolution
    • The history of Genetics
      • Gregor Mendel
      • Analysed different offspring of peas
      • relealized some characteristics were more dominant than others
      • chromosomes observed under a microscope in late 19th century
      • 1950's scientists discovered DNA and genetics
      • led to development of the gene theory
    • Theories of evolution
      • Jean-Baptiste Lamarck
        • suggested that individual animals adapted to suit the environment
          • e.g. giraffes have long necks to reach up to slightly longer trees' so each generation has slightly longer necks.
        • e.g. giraffes have long necks to reach up to slightly longer trees' so each generation has slightly longer necks.
      • suggested that individual animals adapted to suit the environment
        • Charles Darwin
          • all living organisms evolved from simpler life forms
          • survival of the fittest
          • they pass on the survival characteristics to the next generation
      • Accepting Darwin's ideas
        • evidence
          • organisms on different islands had adapted by natural selection
          • breeding experiments with pigeons
        • objections
          • challenged God and ethical objections
          • not enough evidence
          • no way to explain how inheritance happened at this time.
      • Evolution and speciation
        • Alfred Russel Wallace
          • if species existed in various forms, those which were poorly adapted were likely to die out
          • warning colouration on animals
        • Speciation
          • wide range of alleles from genetic variations - that will result from sexual reproduction and mutation = genetic variation
          • where the populations become so different that successful interbreeding is no longer possible
      • Evidence for evolution
        • fossils
          • fossils can give us a clear insight to what an animal looked like
          • extract DNA and compare to modern DNA
          • many animals that are extinct can prove presence
          • however fossils are not always complete
            • many fossils still to be found
            • many organisms died that didn't fossilise
            • little fossil trace of some soft-bodied organisms
      • antibiotic resistant bacteria
        • MRSA (staphylococcus aureus) due to natural selection was not affected by antibiotics
        • important not to overuse antibiotic resistant bacteria
        • important otofinish course of medicine
        • restrict agricultural use of antibiotics
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