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  1. 1. 8.5 The Impact of Microorganisms on Life
  2. 2. Types of Microorganisms Spirogyra sp. Microorganism Characteristics Bacteria <ul><li>Unicellular organisms </li></ul><ul><li>Have cell walls made of a polymer called peptidoglycan. </li></ul><ul><li>Eg: Lactobacillus sp. and Staphylococcus sp. </li></ul>Algae <ul><li>Photosynthetic plant. </li></ul><ul><li>Have chloroplasts and chlorophyll. </li></ul><ul><li>Cell walls are made of cellulose. </li></ul><ul><li>Eg: Spirogyra sp. </li></ul>
  3. 3. Yeast Mucor sp. Euglena sp. Amoeba sp. Paramecium sp. Microorganism Characteristics Fungi <ul><li>Heterotrophic multicellular </li></ul><ul><li>or unicellular eukaryotes. </li></ul><ul><li>Do not have chlorophyll. </li></ul><ul><li>Cell walls made of chitin. </li></ul><ul><li>Eg: Mucor sp. And yeast. </li></ul>Protozoa <ul><li>Unicellular organism. </li></ul><ul><li>Can carry out respiration, reproduction and excretion. </li></ul><ul><li>Use flagella, cilia or pseudopodia to move. </li></ul><ul><li>Eg: Euglena sp., Paramecium sp. and Amoeba sp. </li></ul>
  4. 4. Tobacco mosaic virus Human papilloma virus T4 bacteriophage Microorganism Characteristics Viruses <ul><li>Smallest microorganisms. </li></ul><ul><li>Can only be seen under electron microscope. </li></ul><ul><li>Not a living cell because it cannot survive or reproduce on its own outside the host. </li></ul><ul><li>Must infect and use living cells to reproduce. </li></ul><ul><li>Composed of DNA and RNA surrounded by a protein coat. </li></ul><ul><li>Can be crystallized. </li></ul><ul><li>Eg: T4 bacteriophage and mosaic virus. </li></ul>
  5. 5. Abiotic Components Affecting Microorganisms <ul><li>Activity of microorganisms is affected by abiotic components such as: </li></ul><ul><ul><li>Concentration of nutrients </li></ul></ul><ul><ul><li>pH </li></ul></ul><ul><ul><li>Temperature </li></ul></ul><ul><ul><li>Light intensity </li></ul></ul>
  6. 6. Abiotic component Effect to microorganism Nutrients or water <ul><li>All microorganisms need nutrients and water except virus for reproduction and growth. </li></ul><ul><li>Without it, microorganisms will die or form spores. </li></ul>pH <ul><li>Optimum pH for bacteria: slightly alkaline (pH around 7.4). </li></ul><ul><li>Optimum pH for mould, yeast and protozoa: acidic condition (pH between 4.5 and 5.0). </li></ul>Temperature <ul><li>Low temperature: microorganisms inactive. </li></ul><ul><li>Optimum temperature: 35°C to 40°C. </li></ul><ul><li>Beyond 60°C: growth of microorganisms inhibited. </li></ul><ul><li>Temperature up to 121°C: microorganisms and spores destroyed (sterilization). </li></ul>Light intensity <ul><li>Low light intensity (dark) : the prefer places for microorganisms. </li></ul><ul><li>High intensity of sunlight/ UV rays: can kill microorganism. </li></ul><ul><li>However, algae and photosynthetic bacteria need light to photosynthesis. </li></ul>
  7. 7. The Role of USEFUL Microorganisms in the Ecosystem Useful microorganism Role Decomposers <ul><li>Decomposers (a group of saprophytic bacteria or fungi) carry out decomposition of dead organic remains. </li></ul><ul><li>Decomposers break down dead remains of plants, animals and waste products of animals. </li></ul><ul><li>Release nutrients into the soil. </li></ul>Protozoa in alimentary canal of termites <ul><li>Protozoa such as Trichonympha sp. produce cellulase which digest cellulose (termites feed mainly on wood which contains cellulose). </li></ul>Symbiotic bacteria found in human colon - Synthesize vit B12, vit K Denitrifying bacteria - Nitrogen fixing bacteria : convert atmospheric nitrogen to a form that can be used by plants. - Useful in Nitrogen cycle.
  9. 9. The Effect of Harmful Microorganisms <ul><li>Harmful microorganisms: can cause diseases and spoilage of food and substances. </li></ul><ul><li>Pathogens : microorganisms that cause diseases. </li></ul><ul><ul><li>Body have skin that is protected by a layer of cells. </li></ul></ul><ul><ul><li>Can only cause disease if it getting into body cells (by cut or open wound). </li></ul></ul>
  10. 10. Transmission of Diseases <ul><li>Air </li></ul><ul><li>Water </li></ul><ul><li>Food </li></ul><ul><li>Vectors </li></ul><ul><li>Direct contact </li></ul><ul><li>Indirect contact </li></ul>
  11. 11. Controlling pathogens
  12. 12. The Uses of Microorganisms in Biotechnology <ul><li>Biotechnology – application of biological processes in the manufacturing and servicing industries </li></ul>
  13. 14. Appreciating Biodiversity <ul><li>Biodiversity can be appreciated through conservation and preservation. </li></ul>