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Jacob, Monod, and Pardee constructed a mutant strain of E. coli that carried a lacI- gene mutation (encodes the lac repressor). Which is TRUE of this mutant strain?
a. Transcription of the lac operon is repressed.
b. Transcription of the lac operon does not change.
c. The lac operon is constitutively expressed.
d. Nonfunctional proteins are produced.
e. The lac operon is constitutively expressed and nonfunctional proteins are produced.
Which of the following is NOT one of the major characteristics of the immune system?
A. recognizes and responds quickly to an antigen to which it has responded previously.
B. responds specifically against a particular antigen.
C. produces an inflammation.
D. distinguishes self from nonself
Develop one argument in support of or refuting the following statement: “Viruses are living microorganisms.
The following is an excerpt from a news article:
“Dr. Miller suggests that the germicidal effect may be due to inhibition of protein synthesis. He and his research associates are now set to test this theory in their laboratory over the next two months.”
Explain whether or not the bolded term was used correctly in this example.
Discuss three examples of how humans utilize microbes and their products today.
Discuss how the findings of Louis Pasteur may have inspired Joseph Lister’s development of aseptic techniques in surgical settings.
Compare and contrast the Woese-Fox system with the Whittaker system of classification, discussing how genetic analysis provided information leading to the identification of a third cell lineage.
Differentiate the terms emerging disease and reemerging disease, providing examples of each.
Based upon your reading of Insight 1.1, conduct additional research and discuss the current policy on infectious disease quarantine and how this process is administered in the United States.
You are a scientist researching West Nile virus, a mosquito-borne pathogen. You note that the number of cases of West Nile disease in your county skyrocketed to their highest levels ever this past summer, which also was the wettest summer in 100 years. Using the scientific method, develop a sound hypothesis explaining the increase in disease cases last summer and a method for testing this hypothesis.
Support or refute the following statement: “Double bonding provides the plasma membrane with flexibility.”
The burning of coal imparts a large amount of sulfur dioxide into the atmosphere, which, when combined with water, creates sulfuric acid. Explain how such “acid rain” affects the water chemistry of inland lakes and streams.
Draw a simple model of the following molecules: CH4, NaCl, H2O. Provide a definition of polar molecule, and identify the polar molecule listed here.
Provide a concise summary of the five basic techniques used to manipulate, grow, examine, and characterize microorganisms in a laboratory.
What is the functional type of mannitol salt agar (MSA)? Explain how it is utilized in the isolation and identification of Staphylococcus species.
You are a scientist studying a marsh area contaminated with PCBs, toxic chemical compounds found commonly in industrial waste. Initial microscopic analysis of the soil reveals the presence of motile cells that measure in the micrometer range. You hypothesize that these microbes may be useful in bioremediation of the toxic waste. Thinking about microbial sampling and isolation, describe a method for culturing these microbes back in your laboratory.
Summarize three isolation techniques. Explain which method is utilized most often in a laboratory and how a colony produced by this method can be used to create a pure culture.
Create a short paragraph to differentiate among the following terms: pure culture, subculture, mixed culture, contaminated culture, and stock culture.
For each of the following scenarios, explain which type of microscope(s) would provide the best image.
a. When motility in a live specimen must be viewed
b. When intracellular structures must be viewed
c. When identification of a microbe based on surface structures must be determined
d. When diagnosis of a prion disease must be determined
a. Create a paragraph to differentiate among the following terms: positive stain, negative stain, simple stain, and differential stain.
b. For each of the following scenarios, explain which staining technique(s) should be used.
• Analyzing cell wall composition
• Observing structures for locomotion
• Identifying a structure enhancing pathogenicity
Define the term ubiquitous and explain whether this term can be used appropriately to describe bacteria and archaea.
Provide examples of at least three different structures used for bacterial attachment and explain which are useful in the formation of bioflms.
Based upon your knowledge of cell wall structure, explain how the microbes causing meningitis and typhoid fever can induce fever and systemic shock in an infected patient.
Compare and contrast main characteristics of the three domains of life: Bacteria, Archaea, and Eukarya.
a. Create a branched-tree diagram showing the evolutionary relationship among the three domains of life, and list the characteristics that have led microbiologists to believe the archaea are more closely related to eukaryotes than to bacteria.
b. Which archaeal adaptations make these microbes most suited to extreme habitats?
Quorum sensing is a process used by many bacteria for communication. It involves the production of molecules called auto inducers, which act as bacterial chemo attractants. Describe how a motile bacterium would use its flagellum to respond to such a stimulus in its environment.
a. Describe the characteristics of an endospore-producing bacterium that make it an ideal candidate for bioterrorism but an undesirable intruder in a hospital setting.
b. Explain why the production of endospores is not considered a method of reproduction in most bacterial species.
A microbe has been found in the boiling hot waters of a deep ocean hydrothermal vent. It cannot be readily stained or cultured in the laboratory, but its rRNA has just been sequenced and analyzed.
a. Make a hypothesis regarding the domain of life to which this microbe most likely belongs.
b. Explain which edition of Bergey’s Manual should be used in this case to determine the identity of this microbe.
c. Explain whether the rRNA sequence information is enough to define the species of a microbe.
Summarize the endosymbiotic theory and explain how it accounts for major structural similarities and differences between bacterial and eukaryotic cells.
Compare and contrast the structure and function of the following among bacteria and eukaryotes:
Write a paragraph illustrating the life of a protein, from DNA to mature polypeptide, and the course of its travels within a cell throughout its synthesis.
Summarize the general life cycle of a protozoan, explaining the importance of the various stages in disease transmission and species identification.
Sam has been suffering from diarrhea and abdominal bloating for nearly 2 weeks. Based upon the results of his stool analysis in the laboratory, answer the following:
a. Single-celled organisms were found in the stool sample. Explain whether this evidence indicates an infection caused by a fungus, a protozoan, or a helminth.
b. The single-celled organisms in the stool sample were flagellated. Explain whether this evidence indicates an infection caused by a fungus, a protozoan, or a helminth.
c. Small structures called cysts were found in the stool sample as well as in the well water in the home of the patient. Explain whether this evidence indicates an infection caused by a fungus, a protozoan, or a helminth.
Using the analogy that a cell is like a city, describe the anatomy and functions of each of the major eukaryotic organelles in terms of the role it would play within that fictional city.
a. Describe the process of spore formation and explain how a single fungal spore can lead to the development of a mature mycelium.
b. Candida albicans is a dimorphic fungus. Explain what is meant by this term and discuss which form of growth allows this organism to establish infections within human tissues.
a. Describe three means of motility exhibited by protozoans.
b. Briefly outline the characteristics of the four protozoan groups, listing at least one important pathogen in each group.
a. List the three stages of a complete helminth life cycle and define the role of a definitive host and an intermediate host within this process.
b. Discuss at least three major structural adaptations exhibited by the helminths that provide them the ability to withstand a host environment and multiply to great numbers.
Provide evidence in support of or refuting the following statement: Viruses are simple cellular agents of disease.
a. You identify a novel microbe in your laboratory and find that it possesses two types of nucleic acid. Explain why you immediately rule out the fact that this microbe is a virus.
b. Describe the nucleic acid configuration of a positive-sense RNA virus and explain why its multiplication cycle is less complex than that of a retrovirus.
Define the term tropism, and provide at least one example illustrating how viral structure determines this property of a virus.
Summarize the method used by most companies to manufacture influenza vaccine today, providing one clear advantage and one disadvantage of this process.
a. Provide at least three examples of noncellular infectious agents that do not display typical viral morphology.
b. Of these examples, explain which are associated with the development of human disease.
a. Sketch the basic structure of both a nonenveloped and an enveloped virus, labeling all parts.
b. Discuss the validity of the following statement: The viral capsid and envelope only provide functions that enhance the pathogenicity of a virus.
a. Provide one example of an oncogenic virus and explain the unique properties of its multiplication cycle that allow it to trigger the development of cancer.
b. Compare and contrast the processes of latency and lysogeny, providing examples of latent viruses and lysogenic viruses.
a. Why are viral diseases more difficult to treat than bacterial diseases?
b. You are a researcher aiming to develop a drug to reduce the multiplication of chickenpox (varicella zoster) virus.
Thinking about the steps of the viral multiplication cycle, describe at least three potential targets that would reduce the amount of virus produced by infected cells.
Provide an example of an organism within each of the four main nutritional categories of microbes and describe how each obtains its essential nutrients.
a. Compare and contrast passive and active forms of transport, providing an example of a molecule transported by each and the basic requirements of each process.
b. Describe the process used by a saprobic microbe to transport food particles. How does this compare to how an amoeba feeds?
You are working in a laboratory and are told to prepare a blood sample for microscopic analysis. You prepare a small amount of concentrated blood cells and then suspend the cells in sterile water. When you view the slide, you see nothing but what appears to be fragments of cell membranes.
a. Using principles learned in this chapter, explain why you were not able to see actual red blood cells in your sample.
b. Discuss whether or not you would have been able to visualize bacterial cells prepared in this manner.
a. Define the three cardinal temperatures for a given microbial species.
b. Explain how these temperatures play a role in pathogenicity, or the ability of a microbe to cause disease.
c. Illustrate how it is possible for food to spoil even while properly stored at refrigeration temperatures.
a. Define the term osmophile and provide examples of osmophilic microbes living in the environment and on the human body.
b. Opening the last jar of strawberry jam that he processed at home last June, Sam finds a lawn of fuzzy growth on the surface of the jam. Explain what type of microbe he is most likely seeing and how it could have survived the high sugar environment within the strawberry preserves.
Define each of the following terms and describe where in or on the body you may find such microbes:
-Obligate aerobes anaerobes
-Facultative anaerobes aerotolerant anaerobes
Explain what is happening to the bacterial population in the diagram at the top of page 199. Discuss at which point on the graph it would be best to test the effectiveness of a new antibiotic drug.
While preparing food for the class picnic, Morgan introduces 20 bacterial cells into the pasta salad.
a. During the 3 hours prior to the picnic, the salad sits at room temperature in the classroom. How many bacterial cells are now present, assuming that the generation time is 20 minutes?
b. Using principles learned in this and previous chapters explain how the microbial contamination of the salad could have been prevented or reduced.
What type of ecological association do biofilm communities exhibit? Explain why biofilm infections are so difficult to treat and discuss one potential method for targeting these microbial communities based upon new biofilm research.
a. List four characteristics of an enzyme and explain the role each plays in an enzyme’s catalytic activity.
b. Diagram an enzyme-substrate reaction involving an apoenzyme, making sure to label the active site, the substrate molecule, and the products formed in the reaction.
a. As you learned in previous chapters, fungi are decomposers. Discuss how they might use exoenzymes or endoenzymes to feed.
b. Provide brief definitions of constitutive enzyme and regulated enzyme, explaining one use for each enzyme within a biological cell.
a. Describe the chemical properties of ATP that make it suitable as “metabolic money” within a biological cell.
b. Compare and contrast the processes of substrate-level phosphorylation, oxidative phosphorylation, and photophosphorylation. Provide one example of how each is used in a biological cell.
a. Compare the main reactions of aerobic respiration, anaerobic respiration, and fermentation in a diagram.
b. What are the final electron acceptors in aerobic, anaerobic, and fermentative metabolism? How many ATPs are produced in each process, explaining why this value varies among these biochemical reactions.
a. Draw a bacterial cell and a eukaryotic cell side by side. Label where each of the following steps would take place:
b. Describe the fate of pyruvic acid in strict aerobes, anaerobes, and facultative anaerobes.
Summarize how the electron transport chain functions to produce ATP in a bacterial cell versus a eukaryotic cell. Explain whether or not the term chemiosmosis accurately illustrates this process.
Polymerase chain reaction (PCR) is a technology that requires high temperatures to reproduce DNA fragments. Explain why the discovery of thermophilic archaea and their associated DNA polymerases was critical to the success of this technique.
a. List two common electron carriers used in biological cells and summarize the role they play in the production of ATP.
b. Based upon the information in table, explain which type or types of enzyme supply electrons to thesecarriers.
Saccharomyces cerevisiae is used in the production of wine and beer, while Lactobacillus acidophilus is used in the making of yogurt. Explain why each is biochemically suited to the manufacturing of each of these products.
Explain the relationship among the following terms: genomics, proteomics, gene, protein, genotype, and phenotype.
Provide evidence in support of or refuting the following statement: The life cycle of a retrovirus follows the classical view of the central dogma of biology.
a. Summarize how bacterial and eukaryotic cells differ in gene structure as well as the processes involved in gene expression.
b. A new organism was identified by members of your lab. DNA analysis revealed the presence of introns and what appear to be split genes. Explain whether you have identified a bacterium or a eukaryotic organism.
Sketch a molecule of double- stranded DNA, and explain each of the following:
a. Proper nitrogenous base-pairing between the strands
b. Proper orientation of the strands
c. Proper positioning of the sugar-phosphate backbone
On paper, replicate the following segment of DNA:
5′ A T C G G C T A C G T T C A C 3′
3′ T A G C C G A T G C A A G T G 5′
a. Show the direction of replication of the new strands and indicate the location of the lagging and leading strands.
b. Explain one challenge in the replication of circular DNA and in the replication of linear DNA and how each is resolved in a cell.
Compare the structure and functions of DNA and RNA.
The following sequence represents triplets on DNA:
3′ TAC CAG ATA CAC TCC CCT GCG ACT 5′
Draw a diagram, and describe the following:
a. The mRNA codons that correspond to this DNA sequence
b. The location of ribosome binding within the first two mRNA codons
c. The tRNA anticodons that correspond with the entire mRNA sequence
d. The sequence of amino acids in the polypeptide coded by the mRNA sequence
Define the terms redundancy and wobble in terms of gene expression; using your knowledge of these processes, provide another mRNA sequence that could be used to synthesize the same protein as that in question 6.
Using the DNA sequence in question 6, illustrate and explain the following mutations:
a. A deletion
b. An insertion
c. A substitution
d. A nonsense mutation
e. A frameshift mutation
Use your knowledge of DNA recombination events to complete the following:
a. Propose two ways in which antibiotic resistance may develop in a bacterium.
b. Explain how transposable elements may be used to treat humans with mutations in insulin- producing genes.
c. Describe how bacterial cells acquire the ability to produce toxins.
You are a public health official trying to determine the identity of the pathogen circulating within your city. Explain which genetic technologies would be most useful in this process.
a. Construct a strand of complementary DNA (cDNA) from the following mRNA transcript:
b. What enzyme is used to copy DNA from an mRNA transcript, and why is it necessary to utilize this process to synthesize eukaryotic genes for use in bacterial cells?
a. Explain whether or not DNA polymerase from a mesophilic bacterium could be used successfully in a PCR reaction.
b. If starting with a single double-stranded DNA molecule, how many copies of the DNA would be synthesized after 25 PCR cycles?
c. Provide two applications of PCR technology today.
Conduct additional research and provide evidence in support of or refuting the following statement: All forms of gene therapy used today result in heritable changes.
Based on the following image:
a. Explain where the charges should be applied to this gel in order for the DNA samples to migrate properly.
b. Identify the largest DNA fragment in sample 5. Explain yourselection.
Summarize the goal of the Human Genome Project and discuss three new fields of science that have developed from this research.
a. Outline the main steps in cloning a gene, explaining how horizontal gene transfer is used in this process.
b. Describe one method used to determine whether a bacterial culture has received a recombinant plasmid.
a. Define the term RFLP. Explain how RFLPs are created and why they are useful in DNA analysis.
b. In the following DNA profile, identify the pathogen that is making the two patients ill and explain youranswer.
You work in a laboratory that regularly analyzes patient specimens for the presence of Clostridium difficile.
a. Knowing that many specimens test positive, explain which type of antimicrobial chemical agent you should choose to effectively clean your laboratory each day.
b. Provide an explanation in support of or refuting the following statement: “The goal of disinfection is the destruction of bacterial endospores.” Briefly explain how the type of microorganisms present will influence the effectiveness of an antimicrobial agent.
a. Precisely what is microbial death?
b. Why does a population of microbes not die instantaneously when exposed to an antimicrobial agent?
a. Discuss the factors that influence an antimicrobial agent’s ability to completely remove microbial contaminants from dentures used on a daily basis.
b. Improper cleaning of endoscopes has led to the transmission of hepatitis C infection among patients given colonoscopies at the same facility. Develop one hypothesis to explain how the virus may have persisted and remained infectious.
Compare and contrast the terms bactericidal and bacteristatic in relation to microbial control agents. Develop a simple experimental method that could be used to test whether a control agent exhibits bactericidal or bacteristatic effects.
a. Provide a valid reason for whether or not heat is a selective microbial control agent.
b. Explain the concepts of TDT and TDP, and discuss one example of how these measurements can be modified to produce food for human consumption that is free of microbial contaminants yet still tasty, using examples.
c. What are the minimum TDTs for vegetative cells and endospores?
a. Explain why desiccation and cold are not reliable methods of disinfection. Discuss how food poisoning can occur through the consumption of frozen food that has been properly stored prior to thawing and cooking.
b. Lack of refrigeration on the battlefield makes milk hard to come by. Describe the microbial control method that can allow soldiers to have cream in their coffee and milk on their cereal each morning.
For each item on the following list, select the method that will provide proper sterilization of the item without destroying the material or product. You cannot use the same method more than three times. After considering a workable method, think of one method that would not work. Where an object containing something is given, you must sterilize everything (e.g., both the jar and the Vaseline in it). Some examples of methods are autoclave, ethylene oxide gas, dry oven, and ionizing radiation.
• Room air
• A vial of influenza vaccine
• A pot of soil
• Plastic petri dishes
• Cloth dressings
• Soiled bedding and clothing from an infected patient
• A cheese sandwich
• Green beans for consumption
• Carcasses of cows infected with “mad cow” disease
• Inside of a refrigerator
• Apple juice
• A jar of vaseline
• Fruit in plastic bags
• Human hair (for wigs)
• A flask of nutrient agar
• An entire room (walls, floor, etc.)
• Rubber gloves
• Disposable syringes
• Metal surgical instruments
• Mail contaminated with anthrax spores
Construct a paragraph describing the interrelationship among the microbial pathogen, the affected host, and potential antimicrobial drugs in the development of an appropriate chemotherapeutic treatment.
A critically ill patient enters your emergency room, exhibiting signs and symptoms of severe septic shock. In this case, should you immediately begin treatment with a broad-spectrum drug or a narrow-spectrum drug? Explain your answer and discuss any possible consequences of using either drug in the patient.
HAART, or highly active antiretroviral therapy, is currently recommended for the treatment of HIV and involves the administration of three or more medicines at one time. Explain why this combined therapy approach is more effective than single drug treatment in the management of HIV infection, providing current evidence to support your answer.
You have been directed to aseptically obtain a sample from a growth-free portion of the zone of inhibition in a completed Kirby-Bauer test and inoculate it onto a plate of nonselective medium.
a. After incubation at 37ºC for 48 hours, you observe growth on the plate. Explain this result and how it impacts the analysis of the Kirby-Bauer test.
b. The drug tested was amoxicillin. Based upon your results, explain whether or not this is an effective drug choice for the treatment of an infection caused by this bacterium.
a. Referring to figure, determine whether the cultured bacterium is sensitive, intermediate, or resistant to each of the antibiotic drugs tested and provide an explanation in each case.
b. Referring to figure, determine the minimum inhibitory concentration (MIC) of the drugs being tested, providing an explanation for youranswer.
a. Is it more beneficial for a drug to be microbistatic or microbicidal? Defend your answer.
b. Draw a microbial growth curve, and indicate during which phase an antibiotic should be added to a bacterial culture in order to accurately assess the drug’s microbicidal activity.
Antibiotic-resistance genes, as well as other virulence factor genes, are easily passed between bacterial cells through horizontal gene transfer.
a. Conduct additional research and summarize the unique pathogenic characteristics of Escherichia coli O157:H7; describe how it acquired these traits over time.
b. Conduct additional research on New Delhi metallo-beta-lactamase 1 strains of bacteria, and explain why medical tourism poses a serious threat to the spread of this organism. Provide evidence to support your explanation.
A friend was recently diagnosed with strep throat. One week after his treatment, he redeveloped the infection. In conversation, your friend tells you, “I must have become immune to the drug the doctor gave me!”
a. Discuss the validity of your friend’s statement, providing evidence in support of or refuting his claim.
b. After further conversation, your friend tells you that he stopped taking his initial antibiotics after 2 days because he “felt 100% better.” Explain how this action might have played a role in the redevelopment of his infection.
c. When he returned to his physician, she ordered a test to determine which antibiotic should be prescribed to treat his re-infection. Summarize a test that could be used to obtain this information.
Based upon data from the Human Microbiome Project (HMP):
a. Provide evidence in support of or refuting the following statement: Babies are born sterile.
b. Define microbial antagonism, and discuss how the various microbial populations keep each other “in check,” with consequences for human health.
Trace the path taken by pathogens from various portals of entry, through the establishment of disease, and ending with their exit from various portals in the host.
Discuss the factors that enable the development of healthcare-associated infections. Explain which infection-control measures have been implemented successfully to decrease the spread of these infections.
Dr. John Snow is famous for bringing a cholera epidemic to an end in London by identifying the source of infection as a contaminated water pump used by many in the city.
a. Based upon this information, explain what type of epidemic occurred and draw a curve exhibiting the incidence over time in this type of disease spread.
b. Explain whether or not identifying an index case would have helped Dr. Snow in this situation.
Conduct additional research, and then complete the following.
a. List historical examples of bioterrorism worldwide.
b. Discuss the goal of agroterrorism and potential agents that could be used by an agroterrorist.