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VIRUSES AN 304 Homework 8

Question # 00345589
Subject: Biology
Topic: Biochemistry
Due on: 07/25/2016
Posted On: 07/25/2016 09:46 AM

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Detailed Instructions:
There are three (3) parts to the assignment.
Part A. Multiple Choice (20 questions for 1 point each)
Part B. Short Answer (4 questions for 5 points each)
Part C. Short Essay (6 questions for 10 points each)
Responses to Parts B and C must be written as complete sentences and in your own words (see
Purdue Online Writing Lab (OWL), "Paraphrase: Write in Your Own Words"
( ). You must include complete citations in
APA style for the sources of your information. No points will be earned for answers that do not
include complete and accurate citations for the sources of information used to answer the
question or that support your answer.
Part A Multiple Choice: Select the best or most complete answer (1 point each)
1. In the lab you use the gram staining procedure, a differential staining technique, as a first step
in identifying the type of bacteria on a slide. After you carefully perform the staining
procedure, you look at the cells under the microscope and see purple rod shaped cells. This
result indicates that
a. the cells have a thick peptidoglycan layer as part of the physical structure of the
cell wall and are gram-positive bacilli.
b. the cells have a thin peptidoglycan layer as part of the physical structure of the cell
wall and are gram-positive bacilli.
c. the cells have a thin peptidoglycan layer as part of the physical structure of the cell
wall and are gram-negative cocci.
d. the cells have a thin peptidoglycan layer as part of the physical structure of the cell
wall and are gram-negative bacilli.
e. the cells have a thick peptidoglycan layer as part of the physical structure of the
cell wall and are gram-negative bacilli.
2. Which of the following infectious diseases has (or have) been eradicated in the world?
a. polio
b. measles
c. smallpox
d. whooping cough
e. all of the above
3. Which of the followings is a characteristic of prions that is unique from other known
pathogenic microbes?


a. They lack the characteristics of a classic cell.
b. They can be transmitted from animals to man.
c. They cause permanent damage to the host.
d. They are made entirely of protein.
4. The first microorganism demonstrated to satisfy Koch's postulates (in the late 19th century)
a. Mycobacterium tuberculosis
b. Bacillus anthracis
c. Mycobacterium leprae
d. Vibrio cholera
5. Which of the following is a characteristic of the adaptive immune response and not of the
innate immune response?
a. Physical and chemical barriers
b. Clonal expansions of activated B cells
c. Inflammatory mediators
d. Phagocytosis
6. What does each codon in messenger RNA (mRNA) specify?
a. a nucleotide
b. an enzyme
c. an amino acid
d. a promoter
7. Antigens are
a. specific.
b. proteins or polysaccharides (complex sugars).
c. recognized as foreign by the body's immune system.
d. all of the above.
8. Oncogenes are genes that
a. the virus utilizes to replicate itself.
b. transform normal cells to cancer cells.


c. promote genetic recombination in bacteria.
d. influence ongoing protein production.
9. Genes A, B, and C are three structural genes of an operon and fall in that order within the
operon. A mutation occurs in Gene A that halts transcription early in the gene. What effect
will this have on the levels of proteins produced by Genes A, B, and C?
a. No proteins coded by genes A, B, and C will be produced.
b. Proteins coded by genes B and C, but not gene A, will be produced
c. Proteins coded by genes A, B, and C will be produced.
d. Only proteins coded by gene A will be produced.
10. Plasmids
a. replicate with the bacterial chromosome.
b. may contain antibiotic resistance genes.
c. are as large as the bacterial chromosome.
d. contain genes essential for growth.
11. Interferons are an important part of the host defense against viral infections. Their principal
mode of action is that
a. they trigger the synthesis of one or more cellular proteins that inhibit viral
b. they are present in the serum of healthy individuals and act as viral surveillance
c. they coat viral particles and block their attachment to cells.
d. they protect the death of a viral-infected cell.
12. The form of genetic exchange by which donor DNA is introduced into a recipient bacterial
cell by a bacterial virus is
a. transformation.
b. conjugation.
c. transduction.
d. transfection.
e. vertical transfer.
13. Viruses usually initiate infection by first interacting with receptors on the surface of cells.
Which of the following statements is most accurate about cellular receptors for viruses?


a. Cellular receptors for viruses have no known function.
b. All viruses within a given family use the same cellular receptor.
c. All cells in a susceptible host will express the viral receptor.
d. Successful infection of a cell by a virus may involve the interaction with more than
one type of receptor.
14. What was Edward Jenner's contribution to microbiology?
a. He discovered how to create a vaccine to trigger the body's immune system to
develop antibodies that fight microbes.
b. He proposed the germ theory.
c. He developed the compound microscope.
d. He developed the binomial nomenclature system.
15. The production of RNA using DNA as a template is known as
a. transduction.
b. transformation.
c. transcription
d. translation.
16. Humoral immunity involves the secretion of antibodies from
a. T cells.
b. macrophages.
c. neutrophils.
d. plasma cells.
17. Which of the following describes the correct relationship between the major structures of a
a. The envelope encloses the genome of the virus.
b. The capsid encloses the genome of the virus.
c. The capsid encloses the envelope of the virus.
d. The genome encloses the capsid of the virus.
18. Immunity that results when a person is vaccinated against the 2009-H1N1 influenza is
a. active artificially acquired immunity.


b. passive naturally acquired immunity.
c. active naturally acquired immunity.
d. passive artificially acquired immunity.
19. What are some benefits of our microbiome?
a. It can supply essential nutrients.
b. It can aid in preventing the colonization of pathogens.
c. It can ensure proper functioning of the host immune systems
d. It can aid in food digestion.
e. All of the above
20. Protein toxins that may interfere with host cell function or damage host cell membranes and
are usually secreted by living bacteria are called
a. adhesion factors.
b. antibodies.
c. exotoxins
d. endotoxins.


Part B. Short Answer (5 points each)
Answer the questions below as completely and as thoroughly as possible and where appropriate
include a specific example to illustrate. Answer the question in essay form (not as an outline or
as bullets) using complete sentences. Cite sources of information you used to answer the
questions or that support your answer.
21. Explain how genetic information is transferred from DNA to RNA to proteins. Include the
terms DNA replication, transcription, translation, the principal events and enzymes. Use the
following DNA molecule to illustrate each stage.
3' TACTAGCCACATCTACCGATC 5' Template strand used for transcription
5' ATGATCGGTGTAGATGGCTAG 3' Coding (“inactive” strand)
22. An electron micrograph shows a structure with a rigid outer wall, a membrane, ribosomes, a
nonmembrane bound nuclear area, and no endoplasmic reticulum or mitochondria. Explain
why the structure is or is not each of the following: a human T cell, a virus, a bacterial cell, a
yeast cell.
23. Describe the difference between an emerging and a re-emerging disease and give a recent
example of a viral or a bacterial infection of each and explain the reason for that
24. Name the four types of acquired immunity and describe the mechanisms by which a
person acquires the immunity (“how it is conferred”). In a table describe the
following characteristics for each them: type of immunizing agent (antibodies or
antigen), relative time for immunity to appear, relative time the immunity lasts, and
the source of antibodies (for example, self or non-self) that act against a pathogen or
other antigen
Part C. Short Essay (10 points each)
Answer the questions below as completely and as thoroughly as possible and where appropriate
include a specific example to illustrated. Answer the question in essay form (not as an outline
or as bullets) using complete sentences. You may use diagrams to supplement your answers, but
a diagram alone without appropriate discussion will not be adequate for full credit. Cite sources
of information you used to answer the questions or that support your answer.
25. Your doctor diagnosed your illness as a bacterial sinus infection and prescribed a course of
antibiotics. You also gave informed consent to participate in the doctor’s research study on
antibiotics. As part of the study you went to the clinic every day to have a sample from the
infection taken and analyzed. Before starting on the antibiotics the bacteria were susceptible
to the antibiotic; however later in the week after starting the antibiotic treatment the bacteria
in your infection were resistant to the antibiotic. Results of DNA analysis of the bacteria
causing your infection showed that the resistant bacteria and susceptible bacteria differed
only by a gene that encodes the protein target of the antibiotic such that the antibiotic was
unable to bind to the target site on the resistant bacterial cells..


Which of the following three hypotheses is most likely? Explain how the results support that
hypothesis and what you learned about antibiotic resistance in week 4 topic “Antibiotic
Resistance”. What is a possible mechanism for the change in the gene?
A) You developed a tolerance* for the antibiotic
B) The bacteria infecting you developed a tolerance* for the antibiotic.
C) The bacteria infecting you evolved to be resistant to the antibiotic.
*Tolerance is a nongenetic change in which the response to a specific drug and concentration
is weaker after repeated use.
26. Describe how the first and second lines of defense of your innate immune system can protect
you from an influenza A infection. Recall from week 7 course content topic “About Influenza
Viruses” that influenza is a respiratory disease. Be specific about the tissues, cells, and
processes involved and as related to influenza or other respiratory viral diseases. You might
find "The Innate Immune System Study Guide" in course Module 5 helpful.
27. List the stages of the viral life cycle and briefly describe the principal events in the stages of
the life cycle of a virus in the Retroviridae family and explain what makes viruses in that
family difficult to eliminate from the host. Name a virus in that family.
28. Explain why a secondary antibody response to an antigen may prevent a bacterial or viral
disease when the primary adaptive immune response to that antigen did not protect the
person from the disease. Be specific about the type of cells and products involved in the
29. Read the following Science Daily article:
NIH/National Institute of Allergy and Infectious Diseases. (2016, March 16). Experimental
dengue vaccine protects all recipients in virus challenge study. ScienceDaily. Retrieved July
17, 2016 from
Write a brief summary (one paragraph) about the study that answers the following questions:
What was the purpose of the clinical trial? What was the overall design of the trial? What
were the independent and dependent variables? What was the control and was it a positive or
a negative control? What were the results of the experiments and the major importance of
the findings? Did the trial demonstrate that the vaccine prevented dengue? Why or why not?
Summarize the results in a table. In your summary explain the following terms: virus
challenge study, viremia, and attenuated vaccine.
30. In week 7 topics you learned that genetic reassortment is a mechanism by which
new influenza virus subtypes are produced. Using a virus with an a threesegmented RNA genome as an example, describe and illustrate this
process and include an example of genetic reassortment that resulted in a
major change in the genome (antigenic shift ) creating a new influenza A
subtype. Show all possible outcomes. If you copy/paste an illustration you
must describe in detail what it shows and how it supports your conclusion.
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VIRUSES AN 304 Homework 8

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