Biol 120 Textbook

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Biol 120 Textbook
2010-09-15 03:20:43
Biology Microorganisms

Textbook Questions
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  1. Six Key Properties Associated w/ Living State
    • 1. Compartmentalization & Metabolism
    • 2. Reproduction (growth)
    • 3. Differentiation
    • 4. Communication
    • 5. Movement
    • 6. Evolution
  2. Cells can be thought of as both machines and coding devices. Explain how these two attributes of a cell differ.
    • Machines- Use enzymes to perform chemical transformations
    • Coding Devices- Store and process genetic material (DNA)

    Cell growth and reproduction link these two ideas
  3. What is needed for translation to occur in the cell? What is the product of the translational process?
    RNA and ribosomes are required for translation. Proteins are the product of translation.
  4. What is an ecosystem? Do microorganisms live in pure cultures in an ecosystem? What effects can microorganisms have on their ecosystems?
    An ecosystem is all of the living organisms, together with the physical and chemical constituents of their environments. Microbes usually live and interact with other populations called "microbial communities". Microbes effect ecosystems by carrying out metabolic processes and remove nutrients. Ex. Can remove oxygen.
  5. Why did the evolution of cyanobacteria change Earth forever?
    Produced the oxygen in Earth's atmosphere thus paving the way for the evolution of other organisms.
  6. How could you convince a friend that microorganisms are much more than just agents of disease?
    • Nitrogen fixation of bacteria in plants (legumes).
    • Digestion of cellulose by cattle and sheep.
    • Fermentation for cheese, yogurt, etc.
    • Convert animal waste to methane or ethanol biofuels
  7. For what contributions are Hooke and Leeuwenhoek remembered for microbiology? How did Ferdinand Cohn contribute to bacteriology?
    • Hooke & Leeuwenhoek were early microscopists.
    • Cohn discovered endospores of Bacillus. Also helped discover methods to prevent contamination of culture media.
  8. Explain the principle behind the use of the Pasteur flask in studies on spontaneous generation.
    This flask showed that spontaneous generation did not occur.
  9. What is a pure culture and how can one be obtained? Why was knowledge of how to obtain a pure culture important for development of the science of microbiology?
    Koch found that microorganisms grew in colonies on certain media. Each colony consisted of identical cells. This was necessary to prove that one microbe causes each disease.
  10. Describe a major contribution to microbiology of the early microbiologist Marinus Beijerinck.
    Beijerinck discovered a method of isolating bacteria based on the culture in which it was grown.
  11. What major concepts in microbiology do we owe to Sergei Winogradsky?
    Discovered concept of chemolithotrophy, the oxidation of inorganic compounds.
  12. What major advances in microbiology have occurred in the past 60 years?
    Many advances in microbiology and genetics have been discovered.
  13. What is the function of staining in light microscopy? Why are cationic dyes used for general staining purposes?
    Stains are used to dye organisms to be viewed by microscopes. Cationic dyes are often used because they react and bind to the negative charge of bacterial DNA.
  14. What is the advantage of differential interference contrast microscopy over bright-field microscopy? A phase-contrast microscope over a bright-field microscope?
    • DIC microscopy uses a polarizer to polarize light. The light is defracted by a prism into two beams that hit the organism and recombine in the lens via an interference effect.
    • Better at viewing unstained cells and internal structures than bright-field microscopy.

    Phase contrast is based on the idea that the light passing through specimens will reflect at a different level (refractive index).
  15. What is the major advantage of electron microscopes over light microscopes? What type of electron microscope would be used to view the three dimensional features of a cell?
    Electron microscopes use electrons instead of photons for viewing microorganisms. They allow viewing on the molecular level.

    Scanning Electron Microscopes are best for viewing external features of cell, rather than thin sections.
  16. Why does a cell need a cytoplasmic membrane?
    To allow some substances to enter/exit the cell while restricting the passage of other substances.
  17. Which domains of life have a prokaryotic cell structure? Is prokaryotic cell structure a predictor of phylogenetic status?
    Bacteria and Archaea have prokaryotic cell structure.

    All prokaryotes are not phylogenetically closely related. Archaea are more closely related to eucharya than bacteria.
  18. How do viruses resemble cells? How do they differ?
    Viruses are not dynamic open systems. Unable to replace its parts. It only resembles key characteristics of living systems when it infects a host.