PPT 3

• Prokaryotic cells


  Cells without a nucleus
• Eukaryotic cells


  Cells with a nucleus
• Microbes have extensively shaped the development of the earth's habitats and influenced the evolution of other life forms
• Scientists searching for life on other planets first look for signs of microorganisms
• Eukaryotes


  Organisms whose cells have a nucleus (e.g. Animals, Plants, Fungi, Protists)
• Prokaryotes


  Organisms whose cells do not have a nucleus (e.g. Archaea and Eubacteria)
• Basic structure of cells and viruses

  • Bacteria
  • Fungi
  • Algae
  • Viruses
  • Protozoa
  • Helminths

  
• Viruses


  Small particles that exist at a level of complexity somewhere between large molecules and cells, not composed of cells

  
• Viruses are the most common microbes on earth and can invade their hosts' cells and inflict serious damage and death
• Microbial dimensions

  Range from smallest viruses measuring around 10 nm to protozoans measuring 3 to 4 mm and visible with the naked eye
• Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar
• Bacteria invented photosynthesis long before the first plants appeared, first as a process that did not produce oxygen (anoxygenic photosynthesis)
• Anoxygenic photosynthesis later evolved into oxygenic photosynthesis, which not only produced oxygen but also was much more efficient in extracting energy from sunlight
• Photosynthetic microorganisms (including algae) account for more than 50% of the earth's photosynthesis, contributing the majority of the oxygen to the atmosphere
• Bacteria play a major role in the decomposition of dead matter and wastes, converting soft tissues within the body to liquids and gases
• Without bacteria and fungi, many chemical elements would become locked up and unavailable to organisms, and humans would drown with their own industrial and personal wastes
• Microorganisms are the main forces that drive the structure and content of the soil, water, and atmosphere, producing greenhouse gases that regulate the earth's temperature
• Up to 50% of all organisms exist within and beneath the earth's crust in soil, rocks, and even the frozen Antarctic, forming a major force in weathering, mineral extraction, and soil formation
• Bacteria and fungi live in complex associations with plants, assisting them in obtaining nutrients and water and protecting them against disease
• Households in ancient Egypt kept moldy loaves of bread to apply directly to wounds and lesions
• Human uses of microorganisms

  • Baker's and brewer's yeast (Saccharomyces cerevisiae) - used to make bread rise and ferment sugar to alcohol
  • Penicillium roqueforti - used to make special cheese
• Genetic engineering


  Area of biotechnology that manipulates the genes of microbes, plants, and animals for the purpose of creating new products and genetically modified organisms (GMOs)
• Recombinant DNA (rDNA) technology

  Uses enzymes to cut and paste together DNA sequences of interest, which can then be placed into vehicles called vectors that ferry the DNA into a suitable host cell where it can be copied or expressed
• Bioremediation


  Involves the introduction of microbes into the environment to restore stability or to clean up toxic pollutants
• Microbes have a surprising capacity to break down chemicals that would be harmful to other organisms, handling oil spills and detoxifying sites contaminated with heavy metals, pesticides and other chemical wastes
• One form of bioremediation is the treatment of water and sewage