Genes to ecosystems. Tri 1 Lect 2

  • Created by: Loz1669
  • Created on: 28-12-19 14:55
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  • Genes to Ecosystems
    • Evolution and Natural Selection
      • Changes in gene frequency
        • Ecological change chooses a better selected variant of a population
          • Numbers increase of better selected variant.
            • Genes that determine the better phenotype is more favoured.
      • Modes of selection
        • Stabilising selection
        • Directional selection
        • Diversifying selection
        • Balanced selection
        • Sexual selection
          • Asexual reproduction:
            • Advantages: rapid reproduction
            • Disadvantages: limited variability, limited adaptability
          • Sexual reproduction
            • Advantages: higher variaibility, higher adaptability
            • Disadvantages: lower reproductive rate
      • Speciation: formation of new species. Happens via diversifying selection
        • Mechanisms: 1. Geographical isolation 2. Sympatric separation i.e habitat isolation, behavioural isolation, temporal isolation, mechanical isolation (body parts), gametic isolation (sperm and egg incompatibility), hybrid sterility
    • Genetics: Human and animal development
      • Adult -> Gametes -> Fertilised eggs -> Cell multiplication -> Cell differentiation -> Embryo -> Adult
      • Genetic material is carried on chromosomes
      • Humans has 22 pairs and 1 pair of sex chromosomes
      • Karyotype is the arrangement of chromosomes
      • Diploid: 2 copies of each chromosome
      • Haploid: 1 copy of each chromosome
      • Structure of chromosomes: single molecule of DNA, Long so has to be packaged
      • DNA is wrapped around nucleosomes. These nuclesomes are compact to form a filamant This filament then coils


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