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3.E: Bacterial Genetics (Exercises)

 

These are homework exercises to accompany Kaiser's "Microbiology" TextMap. Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell (unicellular), cell clusters or no cell at all (acellular). This includes eukaryotes, such as fungi and protists, and prokaryotes. Viruses and prions, though not strictly classed as living organisms, are also studied.

3.1: Horizontal Gene Transfer in Bacteria

Study the material in this section and then write out the answers to these questions. Do not just click on the answers and write them out. This will not test your understanding of this tutorial.

  1. Define horizontal gene transfer. (ans)
  2. State three mechanisms of horizontal gene transfer in bacteria. (ans)
  3. Briefly describe the mechanisms for transformation in bacteria. (ans)
  4. Briefly describe the mechanism of generalized transduction in bacteria. (ans)
  5. Briefly describe the following mechanisms of horizontal gene transfer in bacteria:
    1. Transfer of conjugative plasmids in gram-negative bacteria (ans)
    2. F+ conjugation (ans)
  6. Describe R-plasmids, R-plasmid conjugation, and the significance of R-plasmids to medical microbiology. (ans)
  7. Multiple Choice (ans)

3.2: Bacterial Quorum Sensing, Pathogenicity Islands, and Secretion Systems (Injectosomes)

Study the material in this section and then write out the answers to these questions. Do not just click on the answers and write them out. This will not test your understanding of this tutorial.

  1. Define pathogenicity. (ans)
  2. Define virulence. (ans)
  3. Even though a microorganism may be considered pathogenic, it still may not be able to cause disease upon entering the body. Discuss why. (ans)
  4. Define and briefly describe the overall process of quorum sensing in bacteria and how it may enable bacteria to behave as a multicellular population. (ans)
  5. Multiple Choice (ans)

3.3: Enzyme Regulation

Study the material in this section and then write out the answers to these question. Do not just click on the answers and write them out. This will not test your understanding of this tutorial.

  1. Matching

    _____ Regulatory proteins that block transcription of mRNA by binding to a portion of DNA called the operator that lies downstream of a promoter. (ans)

    _____ A molecule that alters the shape of the regulatory protein in a way that blocks its binding to the operator and thus permits transcription. (ans)

    _____ Regulatory proteins that promote transcription of mRNA. (ans)

    _____ A molecule that alters the shape of the regulatory protein to a form that can bind to the operator and block transcription. (ans)

    _____ Producing antisense RNA that is complementary to the mRNA coding for the enzyme. When the antisense RNA binds to the mRNA by complementary base pairing, the mRNA cannot be translated into protein and the enzyme is not made. (ans)

    _____ The induction or repression of enzyme synthesis by regulatory proteins that can bind to DNA and either block or enhance the function of RNA polymerase. (ans)

    _____ The inhibitor is the end product of a metabolic pathway that is able to bind to a second site (the allosteric site) on an enzyme. Binding of the inhibitor to the allosteric site alters the shape of the enzyme's active site thus preventing binding of the first substrate in the metabolic pathway. (ans)

    _____ The inhibitor is the end product of an enzymatic reaction. That end product is also capable of reacting with the enzyme's active site and prevents the enzyme from binding its normal substrate. (ans)

    _____Regulatory proteins that bind to DNA located some distance from the operon they control by working with DNA-bending proteins that enable RNA polymerase can to bind to a promoter and initiate transcription. (ans)

    1. activators
    2. competitive inhibition
    3. corepressors
    4. genetic control
    5. inducer
    6. non-competitive inhibition
    7. repressors
    8. translational control
    9. enhancers
  2. Describe how the lac operon in E. coli functions as an inducible operon. (ans)