Biol 251 lab 5

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Neilgal
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265509
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Biol 251 lab 5
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2014-03-09 15:28:21
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microbiology
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Lab 5
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  1. Describe a capsule and how it surrounds the cell.
    Glycocalyx made of polysaccharides & polypeptides that is well organized tightly bound and surround the bacteria cell.
  2. Explain why capsules are considered virulence factors?
    Because their presence on the bacteria cells increase the chances for serious disease.
  3. Describe a biofilm and the role of capsules in their formation.  Give an example of a biofilm that
    could form in an infection.
    • Biofilm community of bacteria that stack to a surface.
    • Biofilm make the bacteria resistant to antibiotics and increased virulence.
    • Plaque on our teeth is biofilm that can damage the teeth or even kill us if we don't take care of it.
  4. Explain the cycle in some bacteria of making spores and germinating them.   What is the function of
    spores?  Why do bacteria make spores?
    • When environmental conditions become unlivable for some bacteria, they duplicate their chromosome and surrounded by a very thick cortex of peptidoglycan and spore coat
    • which protect the DNA.
    • When the environmental condition become livable the dormant DNA become a vegetative.
    • The function of spores is to protect the DNA from radiation, extreme temperature, harsh chemicals, etc.
  5. Name an encapsulated bacterial pathogen that is a common cause of pneumonia.
    Srteptococcus pneumoniae
  6. Name two genera of bacteria that produce endospores.  Name an important pathogen in each genera.
    • Bacillus and clostridium.
    • Clostridium difficile (C. diff)
    • Basillus anthrachis (cause anthrax)
  7. What properties does an endospore provide the bacterium?  Why for each?
    • allow the DNA to
    • survive extreme conditions such as very high or low temperatures and severe dehydration.  In addition,
    • spores serve as a barrier to the damaging rays of ultraviolet light.
  8. Explain the importance of spores from a clinical standpoint.
    • Endospores are very hard to kill and can infect humans with diseases once enter the body.
    • Hospitals use different methods such high heat ans pressure to kill endospores and prevent infections.
  9. Use your book to give an example of an oral  bacterium with capsules which aids in biofilm
    formation.
    • Two streptococcus species form biofilm on our teeth (plaque).
    • S. mutans & S. sanguis
  10. Monotrichous
    Bacteria with one flagella
  11. Amphitrichous
    Bacteria with one flagella at each end
  12. Peritrichous
    Bacteria with many flagella all around the cell.
  13. Lophotrichous
    several flagella at one end
  14. What is the flagellation pattern in the bacteria in your slide?

    Amphitrichous (Polar flagella)
  15. How do flagella cause motility (see text)?  Why can’t we observe flagella as they are moving?
    • Flagella rotates like a propeller.
    • Because the flagella is below light microscope resolution, we must thicken it with mordant that kill the cell.
  16. What must be done to flagella to view them with the microscope?  Why?
    Thicken with mordant because flagella is below light microscope resolution 0.2 μm.
  17. What is chemotaxis?     Do all bacteria exhibit chemotaxis?
    • Movement toward chemicals (positive chemotaxis) or away from chemicals (negative chemotaxis).
    • No, some bacteria unable to move by themselves
  18. Are flagella virulence factors (discuss with your instructor and classmates)?
    Yes, according to Recent evidence has pinpointed that the bacterial flagella participate in many additional processes including adhesion, biofilm formation, virulence factor secretion, and modulation of the immune system of eukaryotic cells. This mini-review summarizes data from recent studies that elucidated how flagella, as a virulence factor, contribute to bacterial pathogenicity.
  19. What cause separation of DNA fragments during agarose gel electrophoresis?
    Electric current
  20. How can syber green can be used to detect DNA in agarose gels?
    Syber green is a weak dye that bind to DNA or RNA. segments of DNA or RNA will appear green in agarose gels.
  21. How DNA fingerprint appeared? How can it be used to identify an unknown microorganism?
    • In a series of bends pattern
    • Each microorganism has a unique pattern, so the unknown microorganism an be compared to a known microorganism.
  22. How can a mutation change DNA fingerprint?
    A mutation can change the unique bends pattern of a known microorganism.
  23. What is epidemiology?
    The branch of medicine that deals with incidents of distribution and control of diseases.
  24. Give an example of a communicable infectious disease and an example of a non-communicable
    infectious disease.
    • Communicable infectious disease: capable to be transmitted from one individual to another. colds, flues, aids, etc.
    • non-communicable infectious disease: cannot being transferred. Cancer, stroke, etc.
  25. Explain why it is important to definitively identify the microbe causing the outbreak.
    Because some microorganism can cause deadly infections and other only make us very sick, it is important to identify the disease causing microbe to determine which treatment method to use for the infection.
  26. What is herd immunity?  How could it affect an epidemic?
    • collective acquired vaccination.
    • Will eliminate some sort of epidemics.
  27. Draw the results from your picture below.  Compare the fingerprints of Pennsylvania, Alabama, and Missouri virus isolates.  What can you conclude about the virus infecting the Missouri
    patients?
    There is not a death threat to Missouri patients if the DNA fingerprint is matching the Pennsylvania virus.
  28. Why would the restriction fragment patterns from two viruses be different?
    Because they have different genes sequences the restricting enzymes cut them in different places.
  29. Give one advantage and one disadvantage of using DNA for identifying unknowns vs. using
    biochemical analysis.
    • Biochemical analysis identify microbes and gives us more information about the biochemical reactions that the microbe does.
    • DNA fingerprinting allows us to identify the type of microbe without the need to culturing it.

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