Week 3: MicroPara Lec

• The Three Domains of Life

  • Archaea
  • Bacteria
  • Eukarya

  
• Domain Bacteria

  • Have prokaryotic cell structure
  • Lack organelles such as mitochondria and chloroplasts
  • Are devoid of an organized nucleus with nuclear membrane
  • Possess 70S ribosomes that are inhibited by many broad spectrum antibiotics
  • Vast majority are enclosed in a cell wall composed of peptidoglycan
• Domain Eukarya

  • Have eukaryotic cell structure
  • Contain organelles such as mitochondria and chloroplasts, an organized nucleus enclosed in a nuclear membrane
  • Contain 80S ribosomes that are not inhibited by broad spectrum antibiotics
  • Plants, animals, and microorganisms (protozoa, algae, fungi)
• Domain Archaea


  • Exhibit the characteristics of both the Bacteria and Eukarya
  • Considered to be relatives of ancient microbes hat existed during Archean times
  • Possess simple cell structure that lacks organelles and an organized nucleus like bacteria
  • Have 70S ribosomes but the latter are more similar to 80S ribosomes and are not sensitive to antibiotics
  • Have cell wall but is not composed of peptidoglycan
  • Principal habitats are extreme environments (volcanic hot springs, environment with excessively high salt, etc.)
  • Acido-thermophiles, halobacteria, methanogens

  
• Groups of Microorganisms


  • Bacteria
  • Fungi
  • Algae
  • Protozoans
  • Viruses
• Bacteria


  Unicellular, prokaryotic organisms or simple associations of similar cells; multiplication is by binary fission
• Fungi


  Eukaryotic; devoid of chlorophyll; most are multicellular but are not differentiated into roots, stems, & leaves; some are unicellular (yeasts); composed of mycelium; reproduce by budding, fission, spore formation
• Algae


  Simple,unicellular organisms; others are aggregations of similar cells with little or no differentiation in structure or function, although some have complex structure with specialized cell types for particular functions (brown kelp); contain chlorophyll; capable of photosynthesis; found commonly in aquatic environments and damp soil
• Protozoans


  Unicellular, eukaryotic organisms; differentiated on the basis of morphological, nutritional,and physiological characteristics; role in nature is varied (beneficial or detrimental)
• Viruses

  Small noncellular parasites (pathogens) of plants, animals, and bacteria as well as other protists; can only be visualized only by electron microscope; can only be cultivated in living cells
• Gram staining differentiates bacteria into gram-positive (purple) and gram-negative (red)