Chapter 2- The Variety of Living Organisms

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  • Chapter 2- The Variety of Living Organisms
    • Plants
      • Multicellular
        • Bodies made up of many cells
      • Contain chloroplasts=photosynthesis
        • Process using light energy to convert simple inorganic molecules e.g water + co2 into complex organic compounds
      • Make starch through photo' and sucrose= sugar
    • Animals
      • Multicellular
      • No chloroplasts in cells= no photo'
      • Gain nutrition by feeding on other animals/ plants
      • No cell walls
        • Therefore cell can change shape
      • Movement controlled by coordination of nervous system
      • Store carbohydrate in cells as glycogen
    • Fungi
      • e.g mushrooms and toadstools
        • Multicellular
      • Yeast= unicellular
      • No chloroplasts=no photo'
      • Cell walls= made of chitin
      • Cells joined together to form threads= hyphae
      • Saprophytic-> feed by excreting digestive enzymes onto food and absorbing digestive products
    • Protoctists
      • Mixed group of organisms
        • Don't fit into group of plants, animals or fungi
      • Microscopic and single-celled organisms
      • Some resemble animal cells e.g amoeba
        • PROTOZOA
      • Some resemble plants
        • ALGAE
          • Unicellular but e.g. seaweed= multicellular
      • Some have chloroplasts=photo'
      • Some= agents of disease e.g plasmodium-> malaria
    • Bacteria
      • Single-celled organisms
      • smaller < plant/animal/prot cells
      • Simple structure
      • e.g animal cell=10-15 um in diameter
        • Bacteria cell= 1-5 um in length
      • All have cell wall- protects and supports shape of cell
        • Polysaccharides and proteins
          • Some species have layer outside wall= capsule/slimelayer
            • Gives bacteria cell extra protection
      • Underneath cell wall= cell membrane
        • Cytoplasm= centre of cell
          • No nucleus, therefore genetic mat'l in single chromosome within cytoplasm forming circular loop
          • Plasmids in cytop'
            • small circular rings of DNA carrying bacterium's genes
              • DON'T EXIST IN ALL BACTERIUM CELL
                • Some have chlophyll to c/o photo'
      • Some bacteria can swim- propelled by flagella
        • Others do not
      • Most feed off dead organisms
        • Like fungi bacteria can recycle dead organisms and waste products in soil and elsewhere
      • Some used to make food like yoghurt and milk
      • Other bacteria= pathogens i.e cause disease
      • living organisms c/o life processes
    • Viruses
      • All viruses=parasites-> repro inside living cells
        • Need host cell to live in- plant/animal/bacterial cells
          • Viruses smaller < bacteria
      • Viruses not made of cells
        • No nucleus,  cytoplasm, composed of core genetic mat'l surrounded by protein coat
          • Genetic mat'l= DNA, RNA
      • Membrane= envelope surrounds virus particle, stolen form surface membrane of host cell
      • Viruses= no MRS GREN except reproduction
        • Border on being living/non-living organism
      • Reprods by taking over host cells' machinery to make virus particles. After more made-> host cell dies and particles released to infect more cells
        • Viruses e.g influenza made like this
          • However, body's immune system destroys person therefore person recovers
            • Sometimes immune system doesn't destroy virus quickly enough-> causes permanent damage or death. Virus may attack cells (HIV w/c causes AIDS)
      • Some infect plant cells too

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