Exam 3 bio
Mebendazole
Broad spectrum anti-parasitic drugs
8. Distinguish between broad-spectrum and narrow-spectrum antimicrobials, and explain the significance of the distinction.
Broad-spectrum- effective against more that one group of bacteria Narrow-spectrum- target a specific group
Which of the following events might trigger induction of a temperate bacteriophage? An infected cell entering the logarithmic phase of growth Exposure to UV light Bacterial conjugation Normal cell division of an infected cell
Exposure to UV light
What is DOT? Done on Tuesday Department of Transportation Directly Observed Therapy Died of the Treatment
Directly Observed Therapy
Explain what it means when viruses are described as filterable
Early researchers found that when infectious fluids from host organisms were passed through porcelain filters designed to trap bacteria, the filtrate remained infectious. This result proved that an infection could be caused by a cell-free fluid containing agents smaller than bacteria and thus first introduced the concept of a filterable virus.
How does an F+ cell differ from an Hfr cell? Hfr strains can no longer reproduce. F+ cells have no plasmids. Hfr strains have the F plasmid integrated into the chromosome. Hfr cells cannot perform conjugation.
Hfr strains have the F plasmid integrated into the chromosome.
How does an F+ cell differ from an Hfr cell? Hfr strains can no longer reproduce. Hfr cells cannot perform conjugation. Hfr strains have the F plasmid integrated into the chromosome. F+ cells have no plasmids.
Hfr strains have the F plasmid integrated into the chromosome.
How can hospital personnel prevent the spread of resistant Enterococcus faecium throughout the hospital? Hospital staff should wear masks when entering a patient's room. Hospital staff should never serve raw fruit and salads to patients. Hospital staff should wear shoe covers for the duration of their shift. Hospital personnel should wash their hands when entering and leaving a patient's room.
Hospital personnel should wash their hands when entering and leaving a patient's room.
Why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug? Bacteria are especially sensitive to these compounds. The drugs also work against DNA gyrase. Humans and other animal hosts lack peptidoglycan cell walls. They are less expensive that other chemotherapeutic agents.
Humans and other animal hosts lack peptidoglycan cell walls.
Which of the following repair mechanism(s) does not involve DNA polymerase? Light-repair mechanism Excision-repair mechanism Mismatch-repair mechanism
Light-repair mechanism
Which of the following gene mutations could disrupt or change the encoded protein's function? (Select all that apply) Missense Frameshift Silent Transposon
Missense, frameshift, and transposon
13. Identify one example of a fluoroquinolone.
Nalidixic acid
Probiotics
Preparations of live microorganisms that are fed to animals and humans to improve intestinal biota
What must occur for bacterial conjugation to take place? The cells must come into contact with each other. Each cell must contain a plasmid. The cells must transfer RNA. One of the cells must be E. coli.
The cells must come into contact with each other.
Sigma Factors recognize origin of replication Start codons RNA transcripts promoters
Promoters
Where are you likely to find an autoclave? in a chemistry lab in a high school cafeteria in the home in a dentist office
in a dentist office
Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves replication of viral nucleic acid. lysis of the host cell. injection of naked nucleic acid into the host cell. assembly of viral components. adsorption to specific receptors.
injection of naked nucleic acid into the host cell.
18. During the period of ________, a pathogen exhibits its greatest virulence.
invasion
A recombinant cell is a cell that receives DNA from an outside source and incorporates it into its own. is the result of a cell dividing. donates DNA into a new cell.
is a cell that receives DNA from an outside source and incorporates it into its own.
What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell? The DNA is chewed up by enzymes found in the recipient cell. The host DNA integrates, with the prophage, into the new recipient chromosome. The DNA begins to replicate without integrating into the host chromosome.
The host DNA integrates, with the prophage, into the new recipient chromosome.
How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell? The viral DNA may integrate into the host genome during the lytic stage. The host cell is allowed to live during the lytic stage. The host cell dies during the lytic stage. The host cell can only divide during the lytic stage.
The host cell dies during the lytic stage.
How is DNA methylation used in DNA repair? The mismatch-repair enzymes can use a lack of methylation to identify and remove newly synthesized DNA. Methyl groups are required to cut DNA. Methyl groups activate photolysases in light-repair. Methyl groups identify thymine dimers in the DNA.
The mismatch-repair enzymes can use a lack of methylation to identify and remove newly synthesized DNA.
Why are the beta-pleated multimers of PrP potentially pathogenic? They are not detected by other organisms. The multimers are more stable and resistant to protease. They are found on the surface of immune cells, resulting in damage to the immune system. They repress the immune system.
The multimers are more stable and resistant to protease.
How do restriction enzymes cut DNA sequences? They have the ability to cut DNA randomly. They cut DNA at sequences that have lots of adenine bases. They cut DNA at sites, called recognition sites, that have specific nucleotide sequences.
They cut DNA at sites, called recognition sites, that have specific nucleotide sequences.
17. Explain why antiprotozoal and antihelminthic drugs are likely to be more toxic than antibacterial drugs.
They have greater similarities to humans, which make them harder to treat.
How is a complex transposon different from a simple transposon? Complex transposons have one very long insertion sequence. They always integrate in multiple copies into the host genome. Complex transposons code for different types of transposase. They have two simple transposons with another DNA sequence between them.
They have two simple transposons with another DNA sequence between them.
How do scientists ensure that autoclaved materials were actually sterilized? They inspect the materials under a microscope to search for contaminating microorganisms. They may place a sterility indicator with a special dye to detect the growth of endospores. There is no need to verify sterility when proper time, pressure, and temperature are maintained. They may take a sample of the media being sterilized and inoculate it onto a plate for incubation.
They may place a sterility indicator with a special dye to detect the growth of endospores.
In general, how might recombinant DNA technology be used to prevent a genetic disorder caused by a mutation in a single gene? To insert a desirable gene To insert a desirable gene, remove an undesirable gene, or replace a defective gene with a functioning gene To remove an undesirable gene To replace a defective gene with a working gene
To insert a desirable gene, remove an undesirable gene, or replace a defective gene with a functioning gene
What is the end goal of PCR? To quickly increase the number of copies of a specific DNA sequence To increase the pool of different DNA sequences To allow cells to make DNA faster, thereby growing faster
To quickly increase the number of copies of a specific DNA sequence
Which of the following amino acids is coded by only one codon? Tyr Glu His Trp Phe
Trp
19. True/False: The etiology of all infectious diseases can be determined by Koch's Postulates.
True
7. True/False: Your gut biota can determine your mood and mental health.
True
T/F Both base substitution and frameshift mutations can result in the formation of premature stop codons.
True
T/F Dogs do not get measles because their cells lack the correct receptor sites for that virus.
True
T/F In the Ames test, any colonies that form on the control should be the result of spontaneous mutations.
True
T/F Most drugs that interfere with viral multiplication also interfere with host cell function.
True
T/F Mutations that are harmful to cells occur more frequently than those that benefit cells.
True
T/F Positive sense RNA strands of viruses are treated like mRNA inside the host cell.
True
T/F Recombination will always alter a cell's genotype.
True
How is translation terminated? When there are no more charged tRNA molecules When the A, P, and E sites are all filled When a protein called a release factor enters and binds to the A site When the ribosome runs out of the mRNA
When a protein called a release factor enters and binds to the A site
How did the multi-drug-resistant strains of Mycobacterium tuberculosis, like those in the prison, arise? point mutation frameshift mutation conjugation and exchange of resistance factors located on plasmids inclusion of histidine in the patient's diet
conjugation and exchange of resistance factors located on plasmids
A transducing phage contains fragments of the host chromosome instead of the viral genome. cannot infect new host cells. has a viral coat made of host proteins. is a lysogenic bacteriophage.
contains fragments of the host chromosome instead of the viral genome.
A transducing phage contains fragments of the host chromosome instead of the viral genome. cannot infect new host cells. is a lysogenic bacteriophage. has a viral coat made of host proteins.
contains fragments of the host chromosome instead of the viral genome.
Differentiate between a microbe's pathogenicity and it's virulence.
-Pathogenicity: and organisms potential to cause infection or disease. - A microbe's virulence refers to the degree of pathology caused by the organism and is ability to establish itself in a host.
At which point does a recipient cell become an F+ cell? (1) Fusion of the cell membranes (2) Attachment of the sex pilus (3) Transfer of the single stranded F factor (4) Pulling of donor and recipient cells together (5) Formation of the complementary strand of the F factor
5
At which point does a recipient cell become an F+ cell? 1. Fusion of the cell membranes 2. Attachment of the sex pilus 3. Transfer of the single stranded F factor 4. Pulling of donor and recipient cells together 5. Formation of the complementary strand of the F factor 2 4 5 1 3
5
The template strand of a gene reads: 3' ATGCGTAGGACTAAG 5' What is the sequence of the RNA transcribed from this gene? 5' TACGCATCCTGATTC 3' 5' CUUAGUCCUACGCAU 3' 5' UACGCAUCCUGAUUC 3' 5' AUGCGUAGGACUAAG 3'
5' UACGCAUCCUGAUUC 3'
During elongation, how is the RNA synthesized? 3' to 5' Left to right 5' to 3' Right to left
5' to 3'
Which category of antimicrobial drug essentially acts to stall a ribosome as it reads mRNA? tetracyclines chloramphenicol antisense nucleic acids macrolides
macrolides
Which of the following is NOT a goal of recombinant DNA technology? creating organisms capable of producing useful products eliminating undesirable traits from livestock or crops combining genetic material from more than one organism to produce new useful organisms being able to remove or correct damaging traits in humans making it possible to clone humans
making it possible to clone humans
2. Enumerate the sites where normal biota is found in humans.
skin and adjacent mucous membranes, upper respiratory tract, gastrointestinal tract including mouth, outer portion of urethra, external genitalia, vagina, external ear, external eye; New sites: lungs, bladder, breast milk, amniotic fluid and fetus; microbial DNA pos detected: brain, blood stream.
Mice that are injected with only the R strain of Streptococcus pneumoniae stay healthy, because their immune systems can kill this strain easily. are killed, because R strain cells are deadly. become sick for prolonged periods of time.
stay healthy, because their immune systems can kill this strain easily.
RNA that has hydrogen bonded to itself forms a stem loop. terminator sequence. promoter sequence. termination protein.
stem loop.
If Caleb's strain of M. tuberculosis is sensitive to antibiotic treatment, which of the following could be used to treat his infection? Select all that apply. streptomycin penicillins and cephalosporins isoniazid and ethambutol rifampin
streptomycin isoniazid and ethambutol rifampin
What is microbial antagonism? microbes that cause food to smell bad and taste bad microbes that cause disease in humans the ability of the normal flora to outcompete and outgrow pathogens the overgrowth of opportunistic organisms when the normal flora are removed by antiseptic soaps
the ability of the normal flora to outcompete and outgrow pathogens
What is the therapeutic index? the dosage that kills 50% of the patients the range of drug dosage levels that are effective without being excessively toxic the drug dose the patient can tolerate divided by the effective dose the effective dose divided by the dose the patient can tolerate
the drug dose the patient can tolerate divided by the effective dose
When a patient is treated with antibiotics, __________. mutations occur in all of the bacterial cells sensitive bacterial cells multiply uncontrollably the drug will kill or inhibit the growth of all of the sensitive bacterial cells the drug will kill or inhibit the growth of all of the resistant bacterial cells mutations will occur in the sensitive bacterial cells, but not in the resistant bacterial cells
the drug will kill or inhibit the growth of all of the sensitive bacterial cells
Antimicrobial drugs are selectively toxic. This means _____. the drugs will not have toxic effects on a patient the drugs will affect only a particular type of pathogen the drugs are reactive within a specific part of the patient's anatomy (for example, the inner ear) the drugs are more toxic to the pathogens than to the patient
the drugs are more toxic to the pathogens than to the patient
Handwashing with regular soap is effective because __________. the hydrophobic end of the soap molecule attaches to the cell wall of bacteria and the hydrophilic end of the molecule attracts water. The result is that the bacteria are washed away with the water soap is an excellent antimicrobial agent the hydrophobic end of the soap molecule breaks up oily deposits and the hydrophilic end of the molecule attracts water. This combination makes soap a good de-germing agent the fatty acid tail of a soap molecule is an excellent oxidizing agent, while the opposite end of the molecule contains alcohol
the hydrophobic end of the soap molecule breaks up oily deposits and the hydrophilic end of the molecule attracts water. This combination makes soap a good de-germing agent
What is the purpose of an autoclave? to incubate cultures to wash equipment to sterilize equipment and media to warm up cultures
to sterilize equipment and media
The process of acquiring antibiotic resistance by means of bacteriophage activity is called transduction. R-plasmid acquisition. point mutation. transformation.
transduction.
Which of the following will most likely contribute to the spread of a genetic mutation among bacterial species? transduction transformation vertical transmission sexual reproduction transposition
transformation
Quinine
treatment for malaria
Metronidazole
treats mild and severe protozoan intestinal infections
Antiparasitic
treats parasitic infections
3. List the steps a microbe has to take to get to the point where it can cause disease
• Portal of entry (usually thorough skin or mucous membranes) • Attaching to the host (adhesion using fimbriae) • Survive host defenses (Antiphagocytic factors are virulence factor used by pathogens to avoid phagocytes) • Cause disease (Virulence factors: structures, products, or capabilities that allow a pathogen to cause infection in the host)
Which of the following choices correctly matches the class of antibiotic and its mode of action? Select all that apply. Aminoglycosides and tetracyclines are inhibitors of protein synthesis. Penicillins and cephalosporins inhibit nucleic acid synthesis. Sulfonamides inhibit the synthesis of essential metabolites. Lipopeptides inhibit cell wall synthesis.
Aminoglycosides and tetracyclines are inhibitors of protein synthesis. Sulfonamides inhibit the synthesis of essential metabolites.
What is the key difference between donor cells and recipient cells? Cell membranes An F plasmid A chromosome Size
An F plasmid
What is the key difference between donor cells and recipient cells? Size A chromosome Cell membranes An F plasmid
An F plasmid
2. Define opportunism, and list examples of common opportunistic pathogens.
An infectious microorganism that is normally a commensal or does not harm its host but can cause disease when the host's resistance is low. Can be caused by bacterial, viral, fungal, or protozoan pathogens Examples: • Candida albicans - a causal agent of opportunistic oral and genital infections in human. • Staphylococcus aureus - occur as commensal on human skin but may cause staph infections. • Pseudomonas aeruginosa - most common cause of burn and external ear infections, and is the most frequent colonizer of medical devices (e.g.catheters)
Why is DNA replication essential for a cell? An organism must copy its DNA to pass genetic information to its offspring. Because DNA is double-stranded. It allows the organism to repair any mistakes. All organisms require two copies of DNA.
An organism must copy its DNA to pass genetic information to its offspring.
Each of us typically use one or more of a handful of household disinfectants to limit microbial growth around our kitchens and bathrooms. They work in different manners, and their use is often specific to an area of the house. Match each of the methods of microbial control with an example of its use.
An oven is an example of dry heat. Drying out fruit to remove water is an example of desiccation. Ultraviolet rays that damage microbial DNA is an example of nonionizing radiation. Chlorinating pools is an example of halogens. Using isopropanol is an example of alcohols. Using soap is an example of surfactants. Silver creams are examples of heavy metals.
Why is autoclaving rather than boiling water used for sterilization? Boiling water does not kill everything, including bacterial endospores and some protozoan cysts. Autoclaving uses dry heat instead of water. Autoclaving is much faster than boiling water. Boiling water is too hot and may denature proteins.
Boiling water does not kill everything, including bacterial endospores and some protozoan cysts.
Part complete If the inserted sequence had been complete except for missing the last 54 nucleotides (and thus the stop signal), would a working protein be possible? No; an altered DNA sequence would lead to an altered amino acid sequence that would misfold. Lacking the termination codon, the ribosome would continue translating codons in the wrong reading frame until a stop codon is reached. This could lead to an increase in size for the protein, and the additional motifs may interfere with proper folding. Both yes and no are probable. DNA sequencing after the inserted gene would need to be done to see whether any stop signals would be in the correct reading frame or what possible amino acids would be added to the protein. Yes, but the carboxy-terminus of the protein would be lengthened until a stop codon was reached by the ribosome. With the beginning 401 amino acids there, the possibility of the protein motifs required for correct protein folding would be high.
Both yes and no are probable. DNA sequencing after the inserted gene would need to be done to see whether any stop signals would be in the correct reading frame or what possible amino acids would be added to the protein.
Assume that you have an antimicrobial agent specific for each of the targets listed below. Indicate which type of microbe would be most susceptible to the agent by placing it in the appropriate bin.
All bacteria: glycolytic enzymes, membrane proteins Gram-positive bacteria: peptidoglycan Gram-negative bacteria: none Viruses: envelope proteins All bacteria and viruses: nucleic acids
Which of the following are natural microbial components/pathways that scientists now use as tools in genetic engineering and biotechnology? Temperature stable DNA polymerase from thermophiles (ex. Taq) CRISPR/Cas Restriction Enzymes Plasmids Phage or virus transduction All of the above
All of the above
22. Distinguish between drug toxicity and allergic reactions to drugs.
Allergic- heightened immunosensitivity, drugs acts as an antigen Toxicity- foreign chemicals harm human tissue
What term is used to describe bacterial cells that can naturally take up DNA from their environment? competent cells Hfr cells electroporated cells auxotrophs
competent cells
The host DNA is usually degraded during which stage? Biosynthesis Assembly Attachment Release Penetration
Biosynthesis
16. Bacterial ________ are toxic to the host in minute amounts.
endotoxins
Bt crops are engineered in the lab to produce Bt toxins due to the presence of a bacterial gene from B. thuringiensis. Why is it advantageous for the plants to produce the Bt toxin? The Bt toxin will protect the plant from pathogenic bacteria. The plant will release chemicals that will repel all nearby insects. People who eat the food produced by a Bt crop will be resistant to bacterial infections. Insects that normally destroy non-toxin-producing crops will be killed when they eat plants that do produce the toxin.
Insects that normally destroy non-toxin-producing crops will be killed when they eat plants that do produce the toxin.
Which of the following is needed for a transposon to "jump" to a new location in the genome? Insertion sequence Antibiotic resistance gene F plasmid Origin of Transfer
Insertion sequence
12. Explain how drugs targeting folic acid synthesis work.
Interfere with the synthesis of folic acid, which is needed by the bacteria to make DNA/RNA, and amino acids.
16. Name the four main categories of antifungal agents.
Macrolide polyenes, Azoles, Echinocandins, and Nucleotide cytosine analog
Define Incidence
Measures numbers of new cases over a certain period of time. Also called the case or morbitity rate; indicates both rate and risks of infection. Example: 10 kids in daycare got sick this week.
Which of the following repair enzymes cannot repair thymine dimers? Light-repair enzymes Excision-repair enzymes Mismatch-repair enzymes
Mismatch-repair enzymes
Not all changes in amino acid sequence are deleterious, some may even be beneficial. Which of the following point mutations is most likely to alter a protein product without destroying its function? Silent Missense Frameshift Nonsense
Missense
Formalin (37% formaldehyde) is used for antisepsis. sanitization. disinfection. sterilization. both disinfection and sterilization.
both disinfection and sterilization.
Identify better terms for viruses than alive or dead
It is best to describe viruses as either active or inactive
Which category of antimicrobial drug works by changing the shape of a ribosome? oxazolidinones tetracyclines aminoglycosides chloramphenicol
aminoglycosides
Which antimicrobial drugs affect the structure of the ribosome itself? aminoglycosides, antisense nucleic acids, and oxazolidinones aminoglycosides, chloramphenicol, and lincosamides macrolides and antisense nucleic acids tetracyclines and oxazolidinones
aminoglycosides, antisense nucleic acids, and oxazolidinones
What cellular macromolecule is the fertility factor comprised of? Lipid Carbohydrate Nucleic acid Protein
Nucleic Acid
What cellular macromolecule is the fertility factor comprised of? Carbohydrate Protein Nucleic acid Lipid
Nucleic acid
Which of the following types of macromolecules are found in all viruses? Select all that apply. Nucleic acids Polysaccharides Proteins Lipids
Nucleic acids and proteins
Discuss the size of viruses relative to other microorganisms
Smallest infectious agents.
17. A ________ is objective evidence of disease.
sign
Prebiotics
nutrients that encourage the growth of beneficial microbes in the intestine
Differentiate between colonization, infection, and disease?
- Colonization: long-term residency - Infection: breif or acute invasion - Disease: Chronic invasion
Summarize the goals of epidemiology, and differentiate it from traditional medical practice.
- Epidemiology: the study of frequency and distribution of disease and other health-related factors in defined population. ** It involves many disciplines. Epidemiology is different from tradtional medical practice because if focuses on all different forms of disease while tradtional practice only focuses on one and is normally only one discipline.
List the steps a microbe has to take to get to the point where it can cause disease.
- Find a portal of entry - Attach firmly - Survive the host defenses - Cause disease - Exiting the host
Which of the following is most likely a product of an early gene? spike proteins envelope proteins lysozyme DNA polymerase capsid proteins
DNA polymerase
Which of the following build(s) new strands of DNA? The lagging strand Parental DNA The origins of replication The leading strand DNA polymerases
DNA polymerases
Synthetic nucleic acids are useful as DNA probes. primers for PCR. antisense RNAs. DNA probes and antisense RNAs. DNA probes, primers, and antisense RNAs.
DNA probes, primers, and antisense RNAs.
8. List and describe three factors that weaken host defenses and increase susceptibility to infection.
-Old age and extreme youth (infancy, prematurity) -Genetic defects in immunity and acquired defects in immunity (AIDS) -Surgery and organ transplants -Organic disease: cancer, liver malfunction, diabetes -Chemotherapy/immunosuppresive drugs -Physical and mental stress -Other infections
Describe the function and structures(s) of viral capsids
*Capsid:* protein shell that surrounds nucleic acid - Nucleoplasmid: capsid w/ nucleic acid -Most prominent feature of virus -Composed of protein subunits called capsomeres
Provide thorough descriptions of both lysogenic and lytic bacteriophage infections
*Lysogenic Infections:* - Latent infections -Genome becomes incorporated into the host's DNA -Remains like that for an extended period of time -Host cell lives *Lytic Bacteriophage Infections:* -May result in lysis of the cell, -When this happens, the phage is said to have been in the lytic phase or cycle.
Distinguish between enveloped and naked viruses
*Naked (Nucleocapsid):* - Geometric capsid assembled around a nucleic acid strand(s) -Simplest virus *Enveloped:* -Take some of the cell membrane when they are released from a host. -Composed of a nucleocapsid surrounded by a flexible membrane (envelope) -Typically has spikes
Discuss both persistent and transforming infections
*Persistent infections:* -Cell harbors the virus -Not immediately lysed -Can last from a few weeks to the remainder of the host's life -Can remain latent in the cytoplasm *Transformation:* -Virus permanently alters its genetic material, leading to cancer -The transfer of genetic material contained in "naked" DNA fragments from a donor cell to a competent recipient cell
What are the three major types of epidemics?
- Point-source epidimic - Common-source epidimic - Propogated epidimic
2. Identify why some diseases are "notifiable," and provide four examples of such reportable diseases.
- The disease has significant public health significance (TB, Anthrax) - Where disease has significant economic impact on the agricultural industry (FMD, CSF, CBPP) - Where disease has impact on trade (Contagious agalactiae) EX. Rabies, Bluetongue,Vesicular stomatitis, & lumpy skin disease
List several portals of entry and exit.
- Urine - Removal of blood - Coughing - Skin cells - Sneezing - Open incisions - Insect bite - Feces
Diagram the possible configurations that nucleic acid viruses may possess
-*Double-stranded DNA:* -Variola virus (smallpox) -herpes simplex II (genital herpes) *Single-stranded DNA:* -parvovirus (erythema infectiosum)
Determine the term cytopathic effect and provide an example
-Virus induced damage to the cell that alters its microscopic appearance -Ex: syncytia
Analyze the relative importance of viruses in human infection and disease
-Viruses are responsible for billions of infections each year. - Many chronic diseases of unknown cause will eventually be connected to viral agents.
6. Define bioterrorism, and list examples of possible biological agents.
-the use of a biological agent (bacteria, virus, toxin) to intentionally cause disease in civilian populations for the purpose of creating terror -an epidemic may be the end result some can be spread from person to person (smallpox virus) and some cannot (anthrax) certain agents do not cause harm to humans but disrupt the economy (foot and mouth disease virus-- contagious disease of cattle) -capable of causing widespread economic damage and public concern -has almost no capacity to infect humans caused outbreaks in the UK
6. Describe three ways microbes can cause tissue damage.
1) directly through the action of enzymes 2) directly through the action of toxins (both endotoxins and exotoxins) 3) indirectly by inducing the host's defenses to respond excessively or inappropriately.
Describe three ways in which viruses are cultivated
1. Animal inoculation 2. Bird embryos 3. Cell tissue cultures
List several different modes of transmission of infectious agents.
1. Direct or indirect contact with animate or inanimate object. 2. Horizontal transfer: Disease is spread through a population from one infected individual to another. 3. Vertical transfer: disease is transmitted from patient to offspring. 4. Direct contact 5. Indirect transmission in which some vehicle is involved. 6. Biting vectors- mosquito 7. Mechanical vectors
Describe three ways microbes cause tissue damage.
1. Directly through the action of enzymes 2.Directly through the actions of toxins (Bothendotoxins and exotoxins) 3. Indirectly by inducing the hosts defenses to respond excessively or inappropriately.
8. List several virulence factors, and summarize their actions within a host.
1. Exoenzymes: break down and inflict damage on tissues, dissolve host's defense barriers and promote the spread of microbes into deeper tissues (secreted by pathogenic bacteria, fungi, protozoa, and worms) 2. Exotoxin: secreted by a living bacterial cell to the infected tissues Endotoxin: not actively secreted, only found in outer membrane of gram- negative bacteria
List Koch's postulates, and discuss when they might not be appropriate in establishing causation.
1. Find evidence of a particular microbe in every case of a disease. 2. Isolate that microb from an infected subject and cultivate it in pure culture in the lab; preform full icroscopicand biological characterization. 3. Inoculate a susceptible healthy subject with the laboratory isolate and observe the same resultant disease. 4. Riesolate the same agent from the subject. Some infections are not readibly isolated or grown in a lab. When viruses occur outsideof humans. Causation of polymicrobial disease.
6. List the five major targets of antimicrobial agents.
1. Inhibition of cell wall synthesis, 2. inhibition of nucleic acid, 3. inhibition of protein synthesis, 4. interference with cell membrane structure or function, 5. inhibition of folic acid synthesis
List three principal purposes of cultivating viruses
1. Isolate and identify in clinical specimens 2. Prepare viruses for vaccines 3. Do detailed research on viral structure, multiplication cycles, genetics and effects on host cells
Order the following steps from transcription through the initiation of translation.
1. Sigma factor recruits RNA polymerase to the gene promoter on the DNA strand 2. RNA Polymerase begins synthesizing RNA by creating a DNA bubble 3. Terminator DNA sequences loosen the grip of RNA polymerase and rho causes the release of the DNA strand 4. The smaller sunbunit of rRna attaches at the ribosomal binding site on the mRNA strand. 5. fMET-tRNA binds at the start condon 6. The larger subunit of rRNA is recruited
Name two noncellular infectious agents beside viruses
1. Spongiform encephalopathies 2. Prions
Arrange the following statements in chronological order.
1. The Ti plasmid is isolated and prepared for the insertion of foreign DNA 2. The gene for Bt toxin is isolated from the bacterium and inserted into the plasmid 3. The plasmid is taken up by a bacterium 4. The bacterium is used to introduce the Bt toxin gene into the chromosome of plant cells 5. A single plant cell is chosen to produce a plant that now produce Bt toxin
Define healthcare- associated infection, and list the three most common types.
1. Urinary tract 2. Respiratory tract 3. Surgical incisions Healthcare- associated infection: infections acquired or developed during a hospital stay.
13. List Koch's postulates, and explain alternative methods for identifying an etiologic agent.
1. the suspected pathogenic organism should be present in all cases of the disease and absent form healthy animals 2.the pathogenic organism should be isolated from the infected animals and cultivated in pure culture 3.such a culture when inoculated into susceptible animals, should initiate characteristic disease symptoms 4.the pathogen should be re-isolated fmor the experimentally infected animals and shown to be the same as the original pathogen isolated in step 2
Diagram the life cycle of animal viruses
1.*Adsorption:* - The process of adhering one molecule onto the surface of another molecule 2.*Penetration:* - Step in viral multiplication in which virus enters the host cell 3.*Uncoating:* - Process of removal of the viral coat and release of the viral genome by it's new invaded host cell 4.*Synthesis:* -Viral multiplication in which viral genetic material and proteins are made through replication and transcription/translation 5.*Assembly:* -Step in viral multiplcation in which capsis and genetic material are packaged into virions 6.*Release:* -Final step in the multiplication cycle of viruses in which the assembled virus particle exits the host cell and moves moves on to infect another cell.
Name two noncellular infectious agents besides viruses
1.*Spongiform encephalopathies*: -chronic diseases, fatal 2. *Prions*: -Agents of spongiform encephalitis infection -creutzfeldt-jacob disease
It has been determined that the temperature in an autoclave should reach __________ for sterilization. 212 degrees Fahrenheit 121 degrees Fahrenheit 100 degrees Celsius 121 degrees Celsius
121 degrees Celsius
A Salmonella virulence operon has three genes that are important for invasion of host cells. These proteins are not produced when the bacteria are growing outside of the host, and are only produced when the bacteria are growing inside the host. Based on this information, how many promoters are there, and what is the mode of regulation? 1; repressible 3; repressible 1; inducible 3; inducible
1; inducible
Prokaryotes contain _____ ribosomes. 50S 30S 80S 70S
70S
The cytosol of bacteria contain ____________ which has/have components different from those of the functionally equivalent structure of eukaryotes. 70S ribosomes 80S ribosomes a nucleoid a cytoskeleton a nucleus
70S ribosomes
While in the development phase, you are also required to determine both the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for your drug. While these values directly relate to the efficacy of the drug against bacteria, they will also be informative for the next stages of development, which include studies to determine effective dosages within a host. The picture depicts the results of an MBC test. Based on these data, the MIC for your drug would be __________ and the MBC would be __________. There is a scheme representing bacterial sensitivity to an antibacterial drug. There are 3 test-tubes. Each tube contains a bacterial culture. Bacteria from these test-tubes were cultivated on a drug-free media. From the bacterial culture obtained from the tube with the concentration of the drug of 8 micrograms per milliliter bacterial, colonies arose. From the cultures obtained from tubes with the concentration of the drug of 16 and 25 micrograms per milliliter no colonies grew. 8 μg/ml; 25 μg/ml 16 μg/ml; 25 μg/ml 16 μg/ml; 8 μg/ml 8 μg/ml; 16 μg/ml
8 μg/ml; 16 μg/ml
Based on the animation, what is transferred during bacterial conjugation? RNA A conjugation pilus A bacterial plasmid A bacterial chromosome
A bacterial plasmid
What kind of bond is formed when two amino acids join together? A peptide bond An ionic bond A polar bond A hydrogen bond
A peptide bond
Which of the following best explains why the pressure cooker is so important in the canning process? A pressure cooker utilizes normal atmospheric pressure for longer-than-normal cooking times in order to prevent the growth of microbial contaminants and possible endospores. A pressure cooker utilizes steam to create a higher-pressure environment that allows the food to cook at higher temperatures than normal. The higher temperatures kill most contaminating microbes and endospores and therefore effectively sterilize the food. Pressure cookers utilize temperatures that kill only the pathogenic organisms and leave behind the nonpathogenic ones to enhance the flavor of the food. Pressure cookers utilize pressure and dry heat to create an environment that will remove harmful organisms from the food contents. Dry heat is the most effective method of eliminating endospores.
A pressure cooker utilizes steam to create a higher-pressure environment that allows the food to cook at higher temperatures than normal. The higher temperatures kill most contaminating microbes and endospores and therefore effectively sterilize the food.
Lysogenic viral DNA which has integrated into the host genome is referred to as induction. lytic. a prophage. lysogeny.
A prophage
What would happen if the mRNA codon that coded for Cys was mutated in the third position from a U to an A? The codon would now code for Trp instead of Cys. A stop codon would be introduced prematurely. The amino acid Cys would still be coded.
A stop codon would be introduced prematurely.
A strain of E. coli has been isolated from a patient with serious diarrhea. In addition to its chromosome, it has a plasmid. Strains that lose the plasmid become non-pathogenic, and non-pathogenic strains are able to cause diarrhea if transformed with the plasmid. What type of plasmid is this? An (F) plasmid An (R) plasmid A virulence plasmid A bacteriocin plasmid
A virulence plasmid
Which of the following is a characteristic of an F+ cell? Ability to mate with an F- cell Presence of a fertility factor Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell. Ability to synthesize sex pili
Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell.
Which of the following is a characteristic of an F+ cell? Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell. Ability to mate with an F- cell Ability to synthesize sex pili Presence of a fertility factor
Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell.
1. State the main goal of antimicrobial treatment.
Administer a drug to an infected person, which destroys the infective agent without harming the host's cells
Why does the physician start Caleb on the antibiotic azithromycin before laboratory results come back? Antibiotic therapy is started before culture results are obtained because all of the pathogens that cause lower respiratory infections grow very slowly in the laboratory. Caleb would die if treatment were delayed until cultures grew. Antibiotic therapy is started with a broad-spectrum antibiotic because broad-spectrum antibiotics are effective against many gram-positive and many gram-negative bacteria. Antibiotic therapy is started with a narrow-spectrum antibiotic because narrow-spectrum antibiotics are effective against many gram-positive and many gram-negative bacteria. Antibiotic therapy is started with a broad-spectrum antibiotic because broad-spectrum antibiotics are effective against only gram-negative bacteria.
Antibiotic therapy is started with a broad-spectrum antibiotic because broad-spectrum antibiotics are effective against many gram-positive and many gram-negative bacteria.
Antimicrobial X targets a specific protein in the cytoplasm of the bacterial cell, causing the bacteria to stop growing, but does not kill them. A few bacteria start to grow in the presence of antibiotic X. Analysis of the bacteria that can now grow shows that they have changed the shape of the target for antimicrobial X. What conclusion can be made? Antimicrobial X is more effective against the new shape of its target. The change in shape of the target for antimicrobial X had no effect on the effectiveness of antimicrobial X. Antimicrobial X is less effective against the new shape of its target.
Antimicrobial X is less effective against the new shape of its target.
Provide a definition of virulence factor.
Any characteristic or structure of the microbe that contributes to its ability to establish itself in the host and cause damage.
Organisms are either eukaryotes or prokaryotes. Prokaryotes are further classified into the domains Archaea or Bacteria, while all eukaryotes are in the domain Eukarya. All three domains have some cell structures in common, whereas other structures are found in members of only one or two domains. Match the following descriptions of cellular structures with the type of cell in which they are found.
Archaea: Hami, protein cell wall Bacteria: Peptidoglycan cell wall Eukaryotes: Organelles, 80S ribosome in cytosol Both Eukaryotes and Prokaryotes: Cytoskeleton, DNA, Glycocalyx Prokaryotes (Archaea and Bacteria): Fimbriae, 70S ribosome in cytosol
Major characteristic of exotoxins.
Are proteins with a strong specificity for a target cell and extremely powerful, sometimes deadly effects. Affects cell by damaging the cell membrane and initiating lysis and disrupting intracellular functions.
In which stage does formation of mature viruses occur? Assembly Attachment Release Penetration Biosynthesis
Assembly
PFGE is a form of DNA fingerprinting used to compare bacterial isolates. Restriction enzymes are used to generate large DNA fragments that can be separate by gel electrophoresis and compared. On the gel below, which sample has been cut by the most appropriate restriction enzyme for PFGE fingerprinting? Gel electrophoresis. Lane A: Solid purple block in the well. Lane B: Small solid purple block below well. Lane C: purple lines below well decreasing in frequency away from the well. Lane D: purple lines of nearly equal frequency near the bottom of the gel. A B C D
C
What causes thrush? Streptococcus mutans Candida albicans methicillin-resistant Staphylococcus aureus Penicillium notatum
Candida albicans
Dr. Paul Ehrlich observed that the differential stain developed by Dr. Gram suggested bacteria could be killed differentially by chemicals (Chapter 1). He called these potential antibacterial agents "magic bullets". Which among the following cell features of bacteria are potential targets for Dr. Ehrlich's "magic bullets" due to significant difference or absence from humans? Choose all that apply. Glycocalyx Cell wall DNA Cytoskeleton Cytoplasmic membrane Ribosome
Cell wall Ribosome
What is meant by selective toxicity? Chemotherapeutic agents should work on certain types of pathogens. Chemotherapeutic agents should work on many different targets on a pathogen. Chemotherapeutic agents should act against the pathogen and not the host. Chemotherapeutic agents should have only one mode of action.
Chemotherapeutic agents should act against the pathogen and not the host.
1. Differentiate among the terms colonization, infection, and disease.
Colonization is the establishment and multiplication of microbe on the body surface. Infection is colonization by a parasitic microbe. Disease is a noticeable impairment of body function.
Bacterial conjugation is often referred to as bacterial sex. Why is this term inaccurate? Sex is a phenomenon only seen in animals. It does not require two cells to occur. Bacteria are neither male nor female. Conjugation does not result in the formation of new offspring.
Conjugation does not result in the formation of new offspring.
Which statement about conjugation is false? E. coli is the model for bacterial conjugation. Conjugation is a process of bacterial reproduction. After conjugation, each cell involved has a copy of the shared DNA.
Conjugation is a process of bacterial reproduction.
Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains? The cell membranes between the two strands never fuse together. The transferred genes typically recombine with the recipient chromosome. Hfr strains lack fertility factor. Conjugation is typically disrupted before the fertility factor can be transferred.
Conjugation is typically disrupted before the fertility factor can be transferred.
Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains? The transferred genes typically recombine with the recipient chromosome. The cell membranes between the two strands never fuse together. Conjugation is typically disrupted before the fertility factor can be transferred. Hfr strains lack fertility factor.
Conjugation is typically disrupted before the fertility factor can be transferred.
Which of the following is a human disease caused by prions? shingles subacute sclerosing panencephalitis (SSPE) chickenpox (varicella) Creutzfeldt-Jakob disease (CJD)
Creutzfeldt-Jakob disease (CJD)
Which of the following is NOT utilized to culture viruses? bacterial cultures culture media embryonated eggs animal cell cultures laboratory animals
Culture media
Generalized transduction occurs when a bacteriophage inadvertently packages the wrong material into one of its newly-formed protein coats. While the source of this material may vary, it is always: tRNA. miRNA. mRNA. protein. DNA.
DNA
Quinolones and fluoroquinolones act against what bacterial target? Cell walls Bacterial ribosomes Metabolic pathways unique to bacteria Cell membranes DNA gyrase
DNA gyrase
Which of the following attaches the target gene to a desired location? Plasmids Restriction enzymes DNA ligase Chromosomal DNA
DNA ligase
Which statement about DNA replication is FALSE? Because the two strands of parental DNA run in opposite directions, the new strands must be made in different ways. The two strands of parental DNA are separated during DNA replication. DNA ligase adds nucleotides to the lagging strand. DNA polymerase builds a new strand by adding DNA nucleotides one at a time. The lagging strand is made of a series of pieces that must be joined together to make a continuous strand.
DNA ligase adds nucleotides to the lagging strand.
The molecule that seals the gaps between the pieces of DNA in the lagging strand is DNA polymerase. DNA ligase. RNA. the leading strand. the replication fork.
DNA ligase.
According to Strachan's "hygiene hypothesis," certain human behaviors may lead to a decrease in exposure to microbes and, thus, an increase in childhood immune disorders. Place the items associated with decreased exposure to microbes in the bin marked "Decreased Exposure." Place all items associated with increased exposure to microbes the bin marked "Increased Exposure."
Decreased Exposure: discarding away food that falls on floor, wiping surfaces with disinfectants, remaining indoors, washing hands regularly Increase Exposure: being involved in team sports, sharing food or drink with family, having pets, gardening outside
A Gram-positive bacterial strain is simultaneously treated with two different antimicrobials: Drug A, which targets a protein involved in cell wall synthesis, and Drug B, which targets ribosomes involved in translation. The bacteria continue to grow during the course of treatment, indicating resistance to both antimicrobials. What are all the possible resistance mechanisms this bacterial strain could have? Check all that apply. Decreased permeability Drug inactivation Altered drug target Efflux pumps
Decreased permeability Drug inactivation Altered drug target Efflux pumps
Based on the data shown, what are the possible resistance mechanisms of this patient's resistant strain of K. pneumoniae? Decreased permeability Efflux pumps Drug inactivation Altered drug target
Decreased permeability Efflux pumps Drug inactivation Altered drug target
When a nurse rubs your skin with rubbing alcohol prior to administering an injection, what process(es) is he carrying out? Select all that apply. Degerming Antisepsis Sanitization Disinfection
Degerming Antisepsis
Many MRSA strains are sensitive to other antibiotics. Which of the following methods would be the best way to evaluate sensitivity to other antibiotics? Disk diffusion Growth on high salts Gram stain Assay for a PBP2a allele
Disk diffusion
Why does Dr. Bell start Caleb on HIV therapy in addition to the antibiotics used to treat the tuberculosis? Dr. Bell prescribes Caleb extra medications to ensure a high enough dose to completely eliminate both pathogens. Dr. Bell prescribes Caleb HIV therapy because he does not think that Caleb will complete his regimen of antibiotics. Dr. Bell prescribes Caleb HIV therapy because the virus is not affected by the antibiotics used to treat tuberculosis. Dr. Bell prescribes Caleb HIV therapy because in conjunction with the antibiotics, it will eliminate the tuberculosis.
Dr. Bell prescribes Caleb HIV therapy because the virus is not affected by the antibiotics used to treat tuberculosis.
Each phrase below is applicable to a particular mechanism of antimicrobial resistance. Match each phrase to its respective mechanism. Each phrase below is applicable to a particular mechanism of antimicrobial resistance. Match each phrase to its respective mechanism.
Drug activation: Bacterial β-lactamases, antimicrobial altered Efflux pumps: Antimicrobial moved from inside to outside of cell, Active transport, Turning on transport mechanisms Decreased permeability: Bacterial porins, Tuming off transport mechanisms Altered binding site: Structural changes of drug target, Mutation of drug target
Penicillin's target is transpeptidase, a protein involved in cell wall synthesis. For a Gram-positive bacterium, which of the following mechanisms would be most effective in resisting penicillin's effects? Drug inactivation via β-lactamases and altered target binding site Drug inactivation via β-lactamases and use of efflux pumps to move the drug out of the cell Drug inactivation via β-lactamases Decreased permeability via alteration of porins and use of efflux pumps to move the drug out of the cell
Drug inactivation via β-lactamases and altered target binding site
Which of the following is true concerning a lysogenic viral replication cycle? Lysogenic infections are similar to persistent infections in that virus is constantly produced. Once the lysogenic portion of the cycle has begun, virus is never produced again. During lysogeny, the viral DNA is present as a circular plasmid. During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.
During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.
During production of a drug, all work area surfaces must be disinfected using sterilized disinfectants. Which of the following statements about disinfectants are true? Select all that apply. Disinfectants destroy all microbes present on a surface. Disinfection can be used to treat work surfaces as well as workers (i.e., washing hands). Endospores and viruses can resist disinfectant treatment. Disinfection can occur by physical or chemical means. Disinfectants are used to inhibit or destroy pathogens.
Endospores and viruses can resist disinfectant treatment. Disinfection can occur by physical or chemical means. Disinfectants are used to inhibit or destroy pathogens.
10. Explain the significance of beta-lactamases.
Enzymes produced by bacteria that break the lactam ring of penicillins and cephlosporins rendering the drug inactive
1. Summarize the goals of epidemiology and the roles of the Centers for Disease Control and Prevention (CDC).
Epidemiology- effects of disease on the community. The CDC is responsible for keeping track of infectious diseases nationwide.
Which of the following statements is MOST correct regarding the development of antibiotic resistance in populations of bacteria? The bodies of people who take antibiotics become resistant to them. Bacteria exposed to antibiotics alter their DNA to become resistant. Exposure to antibiotics causes mutations which produce resistant bacteria. Exposure to antibiotics selects for the members of a bacterial population which already have a resistant phenotype.
Exposure to antibiotics selects for the members of a bacterial population which already have a resistant phenotype.
Place the steps of F plasmid transfer in the correct order. Single strand of F plasmid is transferred to the recipient cell. One strand of the F plasmid is cut at the origin of transfer. Complement transferred strand is synthesized. F pilus makes contact with the recipient cell.
F pilus makes contact with the recipient cell. One strand of the F plasmid is cut at the origin of transfer. Single strand of F plasmid is transferred to the recipient cell. Complement transferred strand is synthesized.
What is required by an F- cell to become an F+ cell? F plasmid Conjugation pilus An F- cell to be a recipient F+ chromosome
F plasmid
What is required by an F- cell to become an F+ cell? F+ chromosome Conjugation pilus F plasmid An F- cell to be a recipient
F plasmid
6. True/False: The lungs are sterile sites.
False
9. True/False: Babies born by caesarian section are colonized by the same biota as babies born vaginally.
False
T/F Cell-to-cell contact is required for transduction to occur.
False
T/F Glycoprotein spikes are found on the capsids of all viruses.
False
T/F Transposition (insertion of a transposon into a DNA sequence) results in the formation of base substitution mutations in a cell's DNA
False
With this concern in mind, you make plans to increase the stringency of the SSOPs, and develop containment plans to minimize cross-contamination of the nozzles. As long as there is no trace of both bacterial species co-occurring in the same nozzles, you are confident that horizontal gene transfer will not occur. Before you can implement these changes, however, you need to review mechanisms of genetic transfer and gene expression. Consider the following statement: Bacteria can exchange genetic material through conjugation without the need for any protein structures or control mechanisms. Is this statement True or False?
False
14. True/False: If a virus causing a respiratory disease is ingested, it will not cause disease.
False it depends on where it migrates. if the virus can survive Ph then it can survive in small intestine.
Each of the following can be used for the detection and/or identification of viruses except serologic (immunologic) tests observation of cytopathic effects polymerase chain reaction fermentation tests
Fermentation tests
Use of moist heat can control microbial growth in many circumstances, but heat-sensitive items and those susceptible to moisture cannot be sterilized in this manner. Which of the following correctly describes a method of physical control used to control microbial growth on or in such items? Select all that apply. Filtration is the passage of a liquid or a gas through a screenlike material with pores small enough to retain microorganisms. A vacuum is typically used to force the liquid through the mesh, and then the sterile liquid or gas is collected in a sterile container on the other side. Nonionizing radiation, such as UV light, has a wavelength longer than that of ionizing radiation. The wavelengths of UV light are absorbed by cellular DNA in organisms directly exposed to the light. Desiccation is a process that removes water from microorganisms, leaving them unable to grow or reproduce, but still viable. Osmotic pressure is a process that uses high concentrations of salts and sugars to preserve food.
Filtration is the passage of a liquid or a gas through a screenlike material with pores small enough to retain microorganisms. A vacuum is typically used to force the liquid through the mesh, and then the sterile liquid or gas is collected in a sterile container on the other side. Nonionizing radiation, such as UV light, has a wavelength longer than that of ionizing radiation. The wavelengths of UV light are absorbed by cellular DNA in organisms directly exposed to the light. Desiccation is a process that removes water from microorganisms, leaving them unable to grow or reproduce, but still viable. Osmotic pressure is a process that uses high concentrations of salts and sugars to preserve food.
A base insertion or deletion in the translated region of the gene may lead to Silent mutation Frameshift mutation Missense mutation Nonsense mutation
Frameshift mutation
A common mechanism for antibiotic resistance is alteration of the molecule targeted by the antibiotic. Very small changes in the structure to extensive alterations may produce a gene product on which the antibiotic has limited effect. Match the type of point mutation with the type of damage it is most likely to produce.
Frameshift: Extensive change in gene product structure and function. Nonsense: Premature termination of gene product with probable loss of function. Silent: No change in gene product. Missense: Small change in gene product which may or may not alter function.
How is generalized transduction different from specialized transduction? Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage. Only one specific host gene is transferred in both specialized transduction and generalized transduction. Specialized transduction uses animal viruses instead of bacteriophage. Generalized transduction is initiated by a lysogenic bacteriophage; specialized transduction is initiated by a lytic phage.
Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.
How is generalized transduction different from specialized transduction? Only one specific host gene is transferred in both specialized transduction and generalized transduction. Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage. Specialized transduction uses animal viruses instead of bacteriophage. Generalized transduction is initiated by a lysogenic bacteriophage; specialized transduction is initiated by a lytic phage.
Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.
__________ can be used to advise prospective parents about their risk of transmitting genetic disorders, such as Huntington's Disease, to their offspring. Gene therapy Polymerase chain reaction Vaccine production Genetic screening
Genetic screening
Bt crops, including potatoes and cotton, are genetically engineered using laboratory techniques. Which of the following utilizes recombinant DNA technology to produce advantageous traits in the crops that are produced? Genetically engineered crops have natural characteristics that give them a genetic advantage. Genetically engineered crops have a genetic advantage because the parent strains have advantageous traits. Genetically engineered crops have an advantageous gene from another organism inserted into their genome. Genetically engineered crops naturally produce larger plants and bountiful products.
Genetically engineered crops have an advantageous gene from another organism inserted into their genome.
Frederick Griffith did experiments on genetic transformation. Which of the following statements about his experiments is accurate? The combination of living non-encapsulated bacteria and heat-killed encapsulated bacteria did not cause disease. Griffith used only pathogenic bacteria in his experiments. Griffith used bacteria in which the non-pathogenic strain was encapsulated but the pathogenic strain was not. Griffith found that hereditary material released from dead (virulent) bacteria entered live (avirulent) bacteria and changed them genetically, causing them to become virulent.
Griffith found that hereditary material released from dead (virulent) bacteria entered live (avirulent) bacteria and changed them genetically, causing them to become virulent.
Clostridium difficile is a common healthcare associated infection. It is a Gram-positive spore-forming anaerobe that is associated with antibiotic therapy. It is most commonly transferred between patients on the hands of health care workers. Based on this information, rank the following prevention and control strategies from most beneficial (1) to least beneficial (4).
Hand hygiene with soap and water Use of gloves Use of approved chemical disinfectants in patient rooms Hand hygiene with alcohol gels
12. Define healthcare-associated infection, listing common types and their causative agents.
Healthcare-associated infection-Infectious diseases that are acquired or develop during a hospital stay or stay in another health care facility. UTI, Surgical site infections, Lower raspiratory tract infection, gastroenteritis.
The department's microbiology lab has performed strain characterization assays of the biofilm-grown L. monocytogenes isolated from Company Q. These results show new proteins during proteome analysis and new DNA bands from chromosomal digestion. This leads you to conclude that this new strain of L. monocytogenes has been transformed by the addition of new genes for biofilm formation and chemical resistance. Each description below illustrates one way that genetic material is shared between cells. Categorize each item as a HORIZONTAL or VERTICAL gene transfer event.
Horizontal Gene Transfer- gaining a single new gene sequence from outside the cell, infection by a prophage containing a partial bacterial operon, uptake and insertion of a transposable element carrying foreign genes Vertical Gene Transfer- mitosis to fom two daughter cells, two haploid cells fusing to form a diploid cell, binary fission of a bacterial cell
Penicillinase
Hydrolyzes penicillin, found in penicillin-resistant strains of bacteria.
How would you be able to determine if the Tn5 transposon you put into a bacterium integrated into the host genome? The cells would grow at a faster rate than without the transposon. The cells would become longer due to the extra DNA in them. If the Tn5 transposon integrated into the host genome, the cells would show resistance to the antibiotic kanamycin. If the Tn5 transposon integrated into the host genome, the cells would not be able to take in any new tranposons.
If the Tn5 transposon integrated into the host genome, the cells would show resistance to the antibiotic kanamycin.
Why do containers of liquid placed in an autoclave need to remain at least slightly open? If they remain closed, they may implode. A closed container would block any heat from entering the media. to allow oxygen to penetrate the media so that you may pour out the contents into sterile containers before the temperature drops below 100 degrees Celsius
If they remain closed, they may implode.
Where would one find an uncharged tRNA molecule in a ribosome? In the A, P, and E sites In the A site In the A and P sites In the P site In the E site In the P and E sites
In the P and E sites
What is the fate of the prophage during the lysogenic stage? It is degraded by the activity of host defense enzymes. It is copied every time the host DNA replicates. It is packaged into viral proteins and maintained until the host is exposed to an environmental stress. It is released from the cell by lysing the cell.
It is copied every time the host DNA replicates.
How would one increase the concentration of a particular polypeptide in a cell? Increase the level of transcription Increase the concentration of promoters Increase the amount of DNA
Increase the level of transcription
Which operons are never transcribed unless activated? Inducible operons Repressible operons Inducible and repressible operons
Inducible operons
Define infectious dose, and explain its role in establishing infection.
Infectious Dose: The minimum number of microbes necessary to cause and infection to proceed. - If a microorganism has a small infectious dose it has a greater degree of pathology which leads to infections.
Point-source epidimc
Infectious agent came from a single source, and all of it's "victims" were exposed from that source.
5. List examples of emerging and reemerging infectious diseases.
Influenza. Multidrug-resistant tuberculosis (MDR-TB) Nipah virus. Rabies. SARS coronavirus. Tick-borne encephalitis virus. Tick-borne hemorrhagic fever viruses. Crimean-Congo hemorrhagic fever virus.
18. List the three major targets of action of antiviral drugs.
Inhibition of virus entry, inhibition of nucleic acid synthesis, and inhibition of viral assembly/release
Why does a complex transposon often contain an extra piece of DNA between the two insertion elements? The insertion elements require a certain distance between them to function properly. It is often a gene that confers a survival advantage to the host, such as antibiotic resistance. It prevents degradation of the whole transposon.
It is often a gene that confers a survival advantage to the host, such as antibiotic resistance.
What benefit does the F- strain receive from mating with an Hfr strain? It can now produce sex pili. It acquires new, potentially beneficial genes from the Hfr strain. It becomes an F+ cell. It picks up a fertility factor.
It acquires new, potentially beneficial genes from the Hfr strain.
What benefit does the F- strain receive from mating with an Hfr strain? It picks up a fertility factor. It acquires new, potentially beneficial genes from the Hfr strain. It can now produce sex pili. It becomes an F+ cell.
It acquires new, potentially beneficial genes from the Hfr strain.
Why is polymyxin only used on the skin? It can disrupt the metabolic pathways found in humans. It is sensitive to degradation by acid, making oral delivery unsuitable. It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead. It has no effect on bacteria that live in the GI tract..
It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead.
Why would a recombinant DNA molecule be inserted into a host cell? It can protect the recombinant DNA. It can be copied, transcribed, and translated into a desired protein. Plasmids cannot be isolated outside of a host cell. Restriction enzymes can only be used inside of a cell.
It can be copied, transcribed, and translated into a desired protein.
Which of the following statements regarding a bacterium that is R+ is FALSE? It is resistant to certain drugs and heavy metals. It is F+. R+ can be transferred to a different species. R+ can be transferred to a cell of the same species. It possesses a plasmid.
It is F+
What is a nosocomial infection? It is a nutritional deficiency aggravated by hospital food that is served cold. It is a hospital-acquired infection. It is a MRSA infection. It is an infection acquired by swimming in contaminated lake water.
It is a hospital-acquired infection.
What is the function of the conjugation pilus? It converts F- cells into F+ cells. It contains an F plasmid. It pulls the F+ and F- cells together. It carries the chromosome of F- cells.
It pulls the F+ and F- cells together.
What is the function of the conjugation pilus? It pulls the F+ and F- cells together. It contains an F plasmid. It converts F- cells into F+ cells. It carries the chromosome of F- cells.
It pulls the F+ and F- cells together.
What is the function of the parental DNA in replication? It is passed into the offspring of the parent. It gives the cell two complete copies of the DNA. It allows for the DNA to be circular. It serves as the template for DNA replication.
It serves as the template for DNA replication.
3. Describe two methods for testing antimicrobial susceptibility.
Kirby Bauer Procedure and E-Test
Which of the following statements regarding latent viral infections is true? During latent infections, small amounts of virus are produced, and virus numbers build up over time. Latent viral infections are caused by the slow conversion of cellular glycoproteins from normal to infectious form. Latent viral infections are almost always fatal. Latent infections can persist for years in an individual without causing any symptoms.
Latent infections can persist for years in an individual without causing any symptoms.
Major characteristics of Endotoxins.
Lipopolysaccharide (LPS), part of the outer membrane of Gram-negative cell walls. Has a variety of systemic affects on tissue and organs. Causes fever, inflammation, hemorrhage, and diarrhea.
Which of the following contribute to drug resistance in M. tuberculosis? Select all that apply. Many individuals fail to complete their entire regimen of antibiotics. Some physicians prescribe the wrong medication, the wrong dosage, or the wrong length of time for treating tuberculosis. In many areas, tuberculosis antibiotics are unavailable or of poor quality. M. tuberculosis is an acid-fast bacterium; this characteristic allows it to become resistant to antibiotics faster than other bacteria.
Many individuals fail to complete their entire regimen of antibiotics. Some physicians prescribe the wrong medication, the wrong dosage, or the wrong length of time for treating tuberculosis. In many areas, tuberculosis antibiotics are unavailable or of poor quality.
As shown in the animation, the start codon also codes for which amino acid? Methionine Proline Glycine Alanine Serine
Methionine
5. The Human ________ Project collects genetic sequences of microbes from many body sites.
Microbiome
Enumerate the site where normal biota is found in humans.
Most areas of the body in contact with the outside environment harbor resident microorganisms. - Skin and its adjacent mucous membranes - Respritory tract - GI tract -Outer opening of the urethra -External genitalia - Vagina -External ear canal -External eye (lid, conjunctive)
Which of the following statements about antibiotics are TRUE (select all that apply). Most of our antibiotics are produced by a few species of molds and bacteria. Antibiotic resistance means a patient no longer responds to an antibiotic drug. Antibiotics are useful for treating colds and the flu. To reduce resistance it's best to stop taking antibiotics once you feel better. Human misuse of antibiotics spreads resistance because it provides selective pressure. Only people who use antibiotic drugs regularly are at risk for antibiotic resistance. Consuming meat from antibiotic-treated animals will prevent food poisoning.
Most of our antibiotics are produced by a few species of molds and bacteria. Human misuse of antibiotics spreads resistance because it provides selective pressure.
Which of the following is NOT a way in which mutagens increase a cell's mutation rate? Mutagens damage DNA bases causing subsequent errors in DNA replication. Mutagens break the DNA helix inhibiting blocking DNA replication. Mutagens resemble DNA nucleotides and may be used when synthesizing new DNA. Mutagens replicate DNA incorrectly by mismatching bases. Mutagens are inserted between DNA base pairs, distorting the helix.
Mutagens replicate DNA incorrectly by mismatching bases.
20. List 5 cellular or structural mechanisms that microbes use to resist antimicrobials.
New enzymes are synthesized, permeability, drug is immediately eliminated, binding sites for drugs decreased, an affected metabolic pathway is shut down
A base substitution that changes a codon coding for an amino acid to a stop codon is called a Frameshift mutation Missense mutation Silent mutation Nonsense mutation
Nonsense mutation
Which of the following statements concerning prion diseases is true? Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc). Prion diseases affect humans but not other animals. Prion diseases affect brain function but do not affect the morphology (overall appearance) of brain tissues. Prion diseases are always inherited.
Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc).
Which of the following is TRUE of chromosomal conjugation in E. coli? Select ALL that apply. The recipient cells will become F+. The recipient cell will become an Hfr donor. Only part of the chromosome is transferred. The transferred DNA needs to be recombined into the existing recipient chromosome for it to be replicated. The donor cell dies because it has lost its chromosome.
Only part of the chromosome is transferred. The transferred DNA needs to be recombined into the existing recipient chromosome for it to be replicated.
Define opportunism, and list examples of common opportunistic pathogens.
Opportunistic pathogens cause disease when the host's defenses are compromised. Example: Pseudomonas species and Candida albicans.
During the initiation step of translation, the fMet charged tRNA assembles in which site of the ribosome? A site P site E site
P site
The tRNA molecule holding a growing polypeptide chain is at the _____. 50S site A site P site E site
P site
In which stage is the viral DNA introduced into the cell? Assembly Release Attachment Biosynthesis Penetration
Penetration
After T4 lytic phage attaches to an E. coli cell, which of the following occurs? Endocytosis Phage tail fibers pierce the bacterial cell wall so the nucleocapsid can enter T4 phage transfers DNA through the phage's F pilus Phage encoded lysozyme degrades the bacterial cell wall
Phage encoded lysozyme degrades the bacterial cell wall
An R (resistance) plasmid can be transferred from E. coli to Salmonella in culture. Which of the following would suggest that transformation is the transfer mechanism? Plasmid is only found in recipient when there is direct between donor and recipient. Plasmid is only found in the recipient only when F (fertility) plasmid sequences are present. Plasmid is not found in the recipient when DNase is added to the culture medium. Plasmid is found in recipient cells only when phages are present.
Plasmid is not found in the recipient when DNase is added to the culture medium.
14. Name a drug that targets the cellular membrane.
Polymyxin B and E
What role does pressure play in an autoclave? Pressure forces oxygen out of the autoclave. Pressure is applied to boiling water to prevent heat from escaping as steam. The pressure crushes microorganisms. Pressure speeds up the heating process.
Pressure is applied to boiling water to prevent heat from escaping as steam.
4. Discuss the three major types of epidemic, and identify the epidemic curves associated with each.
Prevalence of disease: - Total number of existing cases with respect to the entire population • Incidence of disease - Measures the number of new cases over a certain time period - Also known as case or morbidity rate • Mortality rate: - Measures the number of deaths in a population due to a certain disease
Place the various organisms in order from most resistant to least resistant to antimicrobial agents. Drag the appropriate labels to their respective targets.
Prions Bacterial Endospores Cysts of Cryptosporidium (protozoan) Mycobacteria Cysts of other protozoa Small nonenveloped viruses Active-stage protozoa (trophozoites) Fungal spores Most Gram-negative bacteria Vegetative fungi Large noneveloped viruses Most Gram-positive bacteria Enveloped viruses
How does the number of infectious prions increase? Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion. Prions reproduce by mitosis. Prions reproduce by binary fission. Prions form multimers which can then form more single copies of the prion protein.
Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion.
At each stage of production, sterility of the preparation is a major consideration. When considering appropriate measures to implement to control microbial growth, one must think about the susceptibility of possible microbial contaminants. Apply your knowledge of the structural features of microbes and the mechanisms of action for antimicrobial agents to rank the following microbes according to their susceptibility.
Prions, endospores, Gram-negative bacteria, Gram-positive bacteria, and enevlope virus
In examining a MRSA strain, researchers find that degraded penicillin is found in the culture medium. What is the most likely mechanism of resistance? Alteration of a penicillin-binding protein (PBP) Production of a beta-lactamase Alteration of a porin Production of an efflux pump
Production of a beta-lactamase
Most RNA viruses carry which of the following enzymes? lysozyme ATP synthase reverse transcriptase DNA-dependent DNA polymerase RNA-dependent RNA polymerase
RNA-dependent RNA polymerase
An envelope is acquired during which of the following steps? biosynthesis release penetration adsorption uncoating
Release
Which operons are always transcribed unless deactivated? Inducible operons Repressible operons Inducible and repressible operons
Repressible operons
Differentiate among the various types of reservoirs, providing examples of each.
Reservoir is the primary habitat in the naturalworld from which a pathogen originates. Often a human or animal carrier. Also solid, water, and plants. - Living reservoirs: Animals, mammals, birds, humans. - Nonliving Reservoirs: Soil, water, air.
Resistance Factors
Resistance occurring through horizontal transfer from plasmids
Common-source epidimic
Result to common exposure to a single source of infection over a period of time. Ex. Cities water source.
Propogated epidimic
Results from an infectious agent that is communicable from person to person and is sustained over time in a population. Ex. Influenza
Which statement is CORRECT concerning animal viruses? Enveloped viruses are surrounded by a lipid and carbohydrate coat, which is made from the host cell's mitochondria. Capsid proteins are produced in the nucleus. Retroviruses use an enzyme called reverse transcriptase, which synthesizes DNA by copying RNA. The genome of animal viruses is always single-stranded.
Retroviruses use an enzyme called reverse transcriptase, which synthesizes DNA by copying RNA.
Which of the following are the main causative agents of the common cold? Streptococcus pneumoniae and Haemophilus influenzae Coronaviruses and Streptococcus pneumoniae Rhinoviruses and coronaviruses Rhinoviruses and Streptococcus pneumoniae
Rhinoviruses and coronaviruses
Which finding is most surprising from Griffith's experiments? S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains. R strain cells fail to produce a capsule. S strain cells kill the mice. S strains are able to escape phagocytosis.
S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains.
Which finding is most surprising from Griffith's experiments? S strains are able to escape phagocytosis. S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains. R strain cells fail to produce a capsule. S strain cells kill the mice.
S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains.
11. List six different modes of horizontal transmission, providing an infectious disease spread by each.
STI's, malaria, bubonic plague, Rickettsiae caused typhus, Chagas disease
One aspect that must be evaluated during the development phase is the interaction of your drug with the host (i.e., what effect will the drug have on human cells?). There are several important factors to consider in this interaction, including the selective toxicity of your potential drug. Which of the following statements most accurately describes the principle of selective toxicity? Selective toxicity refers to the fact that antimicrobial agents target a particular microbial structure, molecule, or pathway to exert their effect. Selective toxicity refers to the ability of an antimicrobial to kill microbes with minimal damage to the host. Selective toxicity describes the fact that antimicrobials are more effective against certain microbes compared to others. Selective toxicity refers to the fact that the toxic effect of an antimicrobial varies depending upon the environmental conditions under which it is administered.
Selective toxicity refers to the ability of an antimicrobial to kill microbes with minimal damage to the host.
Which of the following is an application that uses PCR? Sequencing a gene Sequencing a gene, diagnosing a disease, and providing enough DNA for cloning into another organism Diagnosing a disease Providing enough DNA for cloning into another organism
Sequencing a gene, diagnosing a disease, and providing enough DNA for cloning into another organism
Point mutations are those that alter a single base pair or base location, and include substitutions and frameshift mutations. They can range in severity from no phenotypic change to complete loss of function. Rank the following point mutations in order of least damaging to most damaging if they occur in the middle of the coding sequence of a polypeptide.
Silent Missense Frameshift Nonsense
A mutation that affects the genotype of the organism but not the phenotype is called a Nonsense mutation Frameshift mutation Silent mutation Missense mutation
Silent mutation
Which of the following mutations would not result in antibiotic resistance? Missense mutation Nonsense mutation Silent mutation Frameshift insertion Frameshift deletion
Silent mutation
How many codons code for the amino acid arginine? Four Six Three One
Six
What characteristic of the S strain allows it to evade the immune system of the mice? They are genetically engineered to be resistant to killing. They are naturally competent. The cells have a capsule. They are resistant to heat.
The cells have a capsule.
11. Identify two antimicrobials that act by inhibiting protein synthesis.
Streptomycin, Tigecycline
Botulism food poisoning is a preventable illness if special precautions are taken during food preparation. In this case, what could Sue have done to prevent the outbreak of botulism? Select all that apply. Sue noticed that the pressure cooker was malfunctioning during the canning process. She should have fixed the instrument, borrowed a properly working one, or purchased a new pressure cooker. Sue could have lightly heated the food before serving it to her family members. Sue could have boiled the food for at least 10 minutes before serving it to her family members. She could have discarded all of the home-canned food and started over with the same pressure cooker.
Sue noticed that the pressure cooker was malfunctioning during the canning process. She should have fixed the instrument, borrowed a properly working one, or purchased a new pressure cooker. Sue could have boiled the food for at least 10 minutes before serving it to her family members.
Which of the following is an example of microbial control? Select all that apply. Sue washes off the vegetables before serving them in a meal. Mary warms food up in a microwave before putting it on the table. Sue uses bleach to clean the kitchen counters. Mary places leftovers in the refrigerator after the meal.
Sue washes off the vegetables before serving them in a meal. Sue uses bleach to clean the kitchen counters. Mary places leftovers in the refrigerator after the meal.
What is a superinfection? A superinfection is one that is caused by a eukaryotic organism. Superinfection is a disease caused by an organism that is often an opportunist or one that was present in low numbers. Superinfection is a sequel to removal of the normal flora by antibiotic treatment. A superinfection is caused by a multidrug resistant organism. A superinfection is one that is caused by a viral organism.
Superinfection is a disease caused by an organism that is often an opportunist or one that was present in low numbers. Superinfection is a sequel to removal of the normal flora by antibiotic treatment.
Sodium nitrate and sodium nitrite are added to many meat products, such as ham, bacon, hot dogs, and sausage. These additives help to prevent the growth of Clostridium botulinum by inhibiting certain iron-containing enzymes of the organism. This is an example of chemical food preservation. Which of the following correctly describes a method of chemical control used to control microbial growth? Select all that apply. Surface-active agents, or surfactants, decrease surface tension among molecules of a liquid. Phenolics exert antimicrobial activity by injuring lipid-containing plasma membranes, which causes the cellular components to leak out of the cell. Alcohols exert their action by denaturing proteins and dissolving lipids. High pressure is used to denature proteins in vegetative cells.
Surface-active agents, or surfactants, decrease surface tension among molecules of a liquid. Phenolics exert antimicrobial activity by injuring lipid-containing plasma membranes, which causes the cellular components to leak out of the cell. Alcohols exert their action by denaturing proteins and dissolving lipids.
During DNA replication, which nucleotide will bind to an A nucleotide in the parental DNA? U T G A C
T
7. Identify which categories of drugs are most selectively toxic and why.
Tetracyclines
GM crops have raised issues among communities in which they are produced. Which of the following are concerns raised by the public about genetically engineered crops? Select all that apply. Genetically engineered crops could harm the economy. The Bt gene could ultimately make the plants pathogenic to humans. The Bt toxin could result in the death of non-pest species of insects. The Bt toxin could negatively affect the taste of the food that is produced from these crops.
The Bt gene could ultimately make the plants pathogenic to humans. The Bt toxin could result in the death of non-pest species of insects. The Bt toxin could negatively affect the taste of the food that is produced from these crops.
Which of the following best explains how scientists are able to introduce the bacterial gene for Bt toxin into the cotton plant genome? The bacterial gene for Bt toxin is isolated, and the DNA is put into tiny bullets (like BB's) that are "shot" into the cotton plant using a gene gun. The Bt toxin gene is isolated and inserted into a Ti plasmid from Agrobacterium tumefaciens. The engineered Ti plasmid is taken up by a bacterium that infects the cotton plant. A virus is engineered to contain the Bt toxin gene. This virus is then used to infect the plant and pass on the gene. The Bt toxin gene is added to water that is sprayed on the cotton plants. The gene is taken up through the roots of the plant.
The Bt toxin gene is isolated and inserted into a Ti plasmid from Agrobacterium tumefaciens. The engineered Ti plasmid is taken up by a bacterium that infects the cotton plant.
3. Discuss how the Human Microbiome Project has changed our understanding of normal biota.
The HMP will collect genetic sequences in gut, respiratory tract, skin, etc. and tell us what microbes are there. Even microbes that can't be grown in a lab. Also, to figure out the role of normal biota in health and disease
A researcher mistakenly uses a heat-sensitive version of DNA polymerase in a PCR. Which of the following will occur? The PCR will not be able to stop. The PCR will proceed normally. The PCR will proceed normally, but an extremely large number of mistakes will occur. The PCR will stop after one cycle.
The PCR will stop after one cycle.
What characteristic of the S strain allows it to evade the immune system of the mice? They are naturally competent. The cells have a capsule. They are genetically engineered to be resistant to killing. They are resistant to heat.
The cells have a capsule.
What most likely explains the recovery of live S strain cells from a mouse injected with heat-killed S strain mixed with live R strain cells? The R strain picked up the S strain DNA, enabling it to produce a capsule. The S strain was revived by the presence of the host's immune system. The R strain cells picked up the capsules from the S strain cells. The S strain fused with the R strain, making it resistant.
The R strain picked up the S strain DNA, enabling it to produce a capsule.
What most likely explains the recovery of live S strain cells from a mouse injected with heat-killed S strain mixed with live R strain cells? The S strain was revived by the presence of the host's immune system. The R strain cells picked up the capsules from the S strain cells. The R strain picked up the S strain DNA, enabling it to produce a capsule. The S strain fused with the R strain, making it resistant.
The R strain picked up the S strain DNA, enabling it to produce a capsule.
How does the ribosome know if the entering charged tRNA is correct? The incorrect tRNA does not fit into the A site. The anticodon on the tRNA base pairs to the codon on the mRNA. The preceding amino acid will not permit it to enter the A site.
The anticodon on the tRNA base pairs to the codon on the mRNA.
What is meant when a bacterium is said to become "resistant" to an antibiotic? The antibiotic kills or inhibits the bacterium. The antibiotic is metabolized by the bacterium, providing more energy for growth of the cell. The bacterium is neither killed nor inhibited by the antibiotic. The antibiotic mutates in a way that benefits the bacterium.
The bacterium is neither killed nor inhibited by the antibiotic.
If the patient were to get a subsequent urinary tract infection, what should the doctor prescribe knowing that she is susceptible to thrush? The doctor should prescribe the same antibiotic, since it worked, but should also include a medication for a yeast infection. The doctor should prescribe an antibiotic to treat yeast infections to protect against thrush. The doctor should prescribe an antibiotic specific for the bacterial species causing the urinary infection. The doctor should prescribe same antibiotic as before, since it did work, and watch for the development of thrush.
The doctor should prescribe an antibiotic specific for the bacterial species causing the urinary infection.
The preferred method of sterilization during drug production is heat. Heat sterilization can occur in two forms: moist or dry. Autoclaving is the most commonly used application of moist heat for sterilization. Which of the following statements about autoclaving is true? Choose the statement about autoclaving that is true. The effectiveness of an autoclave is dependent on an increase in pressure and corresponding increase in temperature. Autoclaving requires extensive exposure times in order to achieve sterilization. When autoclaving solid items, they should be wrapped in foil to help maintain sterility. Autoclaving is preferred over dry heat because it can effectively be used to sterilize a wide variety of items, including liquids, powders, metal instruments, and glassware.
The effectiveness of an autoclave is dependent on an increase in pressure and corresponding increase in temperature.
What would happen if the only promoter sequence of a gene was deleted? Replication of the gene by DNA polymerase would not occur. The correct reading frame for the protein may not be established. The encoded protein would not be produced. Transcription of that gene would not occur, but ribosomes would translate the gene.
The encoded protein would not be produced.
The project that you are working on was initiated in response to the growing threat of antibiotic resistance in both hospital and community settings. Even in the early discovery and development phase, it is important to think ahead to try to minimize the likelihood that bacteria will be able to evolve resistance to your new drug. Understanding how resistance emerges is an essential part of this process. Which of the following statements is NOT true regarding the evolution of antibiotic resistance in bacteria? The exposure of bacteria to an antibiotic causes the bacteria to produce resistance genes. Due to natural genetic variation within populations, resistant bacteria will be present--even in the absence of antibiotic. Bacteria can acquire plasmids conferring resistance through horizontal gene transfer. Resistance can emerge due to mutations in chromosomal genes.
The exposure of bacteria to an antibiotic causes the bacteria to produce resistance genes.
What was the MOST likely source of the family's botulism food poisoning? The family consumed botulism toxin in the chicken. The family consumed botulism toxin in the canned tomatoes. The family consumed botulism toxin in the canned green beans. The family consumed botulism toxin in the spinach salad.
The family consumed botulism toxin in the canned green beans.
How does genotype determine phenotype? Through the use of repressor genes, an individual can consciously create the physical features (phenotype) desired. The genotype includes all of the DNA of an individual and, therefore, provides information to make all phenotype structures. The genotype gives instructions for the structural, enzymatic, and regulatory proteins which result in the phenotype. The genotype directly gives instructions to make the proteins, carbohydrates, and lipids used to build the organism.
The genotype gives instructions for the structural, enzymatic, and regulatory proteins which result in the phenotype
What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell? The host DNA integrates, with the prophage, into the new recipient chromosome. The DNA begins to replicate without integrating into the host chromosome. The DNA is chewed up by enzymes found in the recipient cell.
The host DNA integrates, with the prophage, into the new recipient chromosome.
Which statement about DNA replication is CORRECT? The leading strand is built continuously, and the lagging strand is built in pieces. The lagging strand is built continuously. The lagging strand is one of the strands of parental DNA. DNA ligase helps assemble the leading strand. The leading strand is one of the strands of parental DNA.
The leading strand is built continuously, and the lagging strand is built in pieces.
Why is light required for photolysases? The light provides the energy to break the bonds between the thymine dimers. Light is used to activate the DNA polymerase to repair the gap. The light helps identify the damaged strands. Light excises the section of DNA to be repaired.
The light provides the energy to break the bonds between the thymine dimers.
Where on the DNA strand does a repressor bind? The operator The promoter The structural genes The inducer
The operator
Why are endospores sometimes used in sterility indicators? They are the hardest life form to kill. They release toxic gases that aid in the sterilization process. Endospores have the ability to kill all remaining microbes. Bacterial endospores release an indicator dye used to test for sterility.
They are the hardest life form to kill.
Competitive Inhibition
The process of a substance reducing the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics.
What is the initial target of RNA polymerase? The terminator region The template DNA The promoter
The promoter
How does specialized transduction differ from regular lysogeny? The prophage in specialized transduction carries with it pieces of the host chromosomal DNA. The resulting bacteriophage from specialized transduction cannot infect a new host cell. The prophage is not excised during specialized transduction. The resulting bacteriophage from specialized transduction does not contain any viral DNA.
The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.
How does specialized transduction differ from regular lysogeny? The prophage is not excised during specialized transduction. The resulting bacteriophage from specialized transduction does not contain any viral DNA. The resulting bacteriophage from specialized transduction cannot infect a new host cell. The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.
The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.
How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population? The phage lyses the bacterium and releases resistance genes into the local environment, which can then be taken up by recipient cells. The phage causes the destruction of any antibiotic present during the specialized transduction process. The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.
The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.
How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population? The phage lyses the bacterium and releases resistance genes into the local environment, which can then be taken up by recipient cells. The phage causes the destruction of any antibiotic present during the specialized transduction process. The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.
The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.
4. Define therapeutic index, and identify whether a high or a low index is preferable.
The ratio of the dose of the drug that is toxic to humans as compared to its minimum effective dose. The smaller the ratio the safer the drug.
A lytic virus has infected a patient. Which of the following would best describe what is happening inside the patient? The virus is infecting cells and then releasing only small amounts of virus. The virus is incorporating its nucleic acid with that of the patient's cells. The virus is causing the death of the infected cells in the patient. The virus is not killing any cells in the host. The virus is slowly killing the patient's cells.
The virus is causing the death of the infected cells in the patient.
What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage? The virus would infect new hosts. The cell could still be revived by the virus. The virus would not be able to infect new hosts.
The virus would not be able to infect new hosts.
Which of the following genetic elements is transcribed into a single mRNA? The promoter The operator The structural genes The inducer The repressor
The structural genes
Define Prevalence
The total number of existing cases with respect to the entire population. Reported as the percent of the population have a particular disease at a given time. 50 out of 200 kids at a daycare have E.coli.
Explain what is meant by a disease being "notifiable" or "reportable," and provide examples.
They are diseases that must be reported to the authorities. Example: Anthrax, plauge, smallpox, HIV, Lyme disease.
Explain the importance of viral surface proteins or spikes
They are essential for the attachment of viruses to the next host cell
What is unique about transduction compared to normal bacteriophage infection? Transduction transfers DNA from the chromosome of one cell to another. The bacteriophage does not erupt from an infected cell during transduction. The bacteriophage takes fragments of the cell with it during transduction.
Transduction transfers DNA from the chromosome of one cell to another.
Which of the following is an example of horizontal gene transfer in bacteria? Transduction Conjugation and transformation Conjugation Transformation Transduction, conjugation, and transformation
Transduction, conjugation, and transformation
What is the hallmark of all horizontal gene transfers? Transfer of DNA from parent to offspring Transfer of DNA using a virus The use of plasmids Transfer of DNA between organisms of the same generation
Transfer of DNA between organisms of the same generation
What are the products of semiconservative replication for a double-stranded DNA molecule? Two double-stranded DNA molecules, one consisting of two parental strands and the other consisting of two daughter strands. One double-stranded DNA molecule, consisting of two daughter strands. One double-stranded DNA molecule consisting of one parental strand and one daughter strand. Two double-stranded DNA molecules, each consisting of one parental strand and one daughter strand.
Two double-stranded DNA molecules, each consisting of one parental strand and one daughter strand.
Which of the following statements regarding vectors is FALSE? A useful vector contains multiple restriction sites for insertion of DNA. Cloning vectors include a "marker" to facilitate identification of cells containing them. Vectors are generally over 100,000 base pairs in size. Cloning vectors frequently contain sequences necessary for expression of inserted sequences. Vectors are usually autonomously replicating DNA molecules.
Vectors are generally over 100,000 base pairs in size.
Discuss the primary reason that antiviral drugs are more difficult to design than antibacterial
Viral infections are difficult to treat because the drugs that attack viral replication also cause side effects in the host.
Why is it difficult to find good chemotherapeutic agents against viruses? There is no effective way to deliver the drug to the virus. Viruses are not cells, and therefore not sensitive to such compounds. Viruses depend on the host cell's machinery, so it is hard to find a viral target that would leave the host cell unaffected. Viruses infect both bacteria and human cells.
Viruses depend on the host cell's machinery, so it is hard to find a viral target that would leave the host cell unaffected.
Which of the following statements best describes why antibiotics are ineffective treatments for the common cold? Viruses contain drug pumps that pump antibiotic out of the virus before the antibiotic can reach its target. Viruses contain enzymes that deactivate antibiotics before they can reach their targets. Viruses are constantly mutating and changing their antibiotic targets. Viruses do not possess targets for antibiotics.
Viruses do not possess targets for antibiotics.
23. Explain what a super infection is and how it occurs.
When therapy destroys beneficial resident species, other microbes that were once in small numbers begin to overgrow and cause disease.
Which of the following is NOT an important consideration when preparing to use a chemical to disinfect a diaper changing table in a public restroom? View Available Hint(s) Whether or not the changing table is visibly soiled The label directions for contact time Whether or not the chemical is compatible with the material that the changing table is made of Whether or not hand sanitizer is available at the changing table
Whether or not hand sanitizer is available at the changing table
Discuss how the Human Microbiome Project will change our understanding of normal biota.
Will identify genetic sequences to determine which microbs are inside and on humans, even though they can't be cultured in a laboratory. Will determine what the normal biota play in human health.
Parenteral
administering drugs via IV
Which category of drug is complementary to mRNA of the pathogen? oxazolidinones tetracyclines macrolides antisense nucleic acids
antisense nucleic acids
GAU codes for serine. proline. tryptophan. isoleucine. aspartic acid.
aspartic acid.
One alternative to autoclaving for sterilization of liquids is filtration. Imagine that you are using a filter to sterilize a drug solution. You use a filter with a 0.22 μm pore size. Which of the following microbes will effectively be removed by this filter? Select all that apply. bacteria such as E. coli yeast fungi small viruses
bacteria such as E. coli yeast fungi
The use of lysozyme during the preparation of cheeses and wines is effective in reducing the numbers of bacteria. fungi. prions. all microbes. viruses.
bacteria.
R-plasmids are most likely acquired via Check all that apply. translation. bacterial conjugation. transformation. transduction.
bacterial conjugation
Strachan suggested the "hygiene hypothesis" in 1989, although his idea is almost impossible to demonstrate experimentally. Since Strachan's hypothesis is almost impossible to demonstrate using experimentation, how did he most likely arrive at such an assertion? through the observation that older people rarely get sick by comparing vaccination records of individuals with immune disorders and those without by intentionally exposing children to various pathogens by comparing cases of allergy-associated disorders from years past to those of the present
by comparing cases of allergy-associated disorders from years past to those of the present
Put the following events in the construction of a recombinant DNA molecule in the correct order: a. ligation of desired gene to plasmid DNA b. introduction of the plasmid into bacteria c. restriction enzymes cut gene of interest and plasmid DNA d. growth of cells on an antibiotic-containing medium a, d, c, b b, c, a, d c, a, b, d d, a, b, c
c, a, b, d
Competent cells are cells that can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination. are killed by heat. are also considered "rough-strain" based on colony phenotype. have the ability to produce capsules.
can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination.
Competent cells are cells that can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination. have the ability to produce capsules. are killed by heat. are also considered "rough-strain" based on colony phenotype.
can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination.
Clavulanic acid
chemical added to some penicillin's to inhibit
Which of the following is NOT used by bacteria to acquire new genetic material? conjugation transduction transformation crossing over
crossing over
Generalized transduction involves bacteriophages that can randomly integrate into the host genome digest (or fragment) the host genome transfer F plasmids package naked DNA from the environment
digest (or fragment) the host genome
Antiviral
drug that inhibits viral infections
Selective toxicity
drugs kill or inhibit microbial cells without harming the host
11. ________ diseases are caused by newly identified microbes.
emerging
9. A(n) _______ disease is seen at a steady frequency over a long period of time in a particular location.
endemic
Beta-lactamase
enzymes produced by bacteria that break the lactam ring of penicillins and cephlosporins rendering the drug inactive
Which of the following could be used to sterilize objects such as medical devices? silver nitrate orthophenylphenol ethylene oxide 100% alcohol
ethylene oxide
4. A condition in which pathogenic microorganisms penetrate host defenses, enter the tissues, and multiply is a(n) ________.
exogenous infection
If a scientist discovers a new gene, a functional genomic study using __________ may be used to determine what the gene does. gene knockout Southern blots PCR electrophoresis
gene knockout
Rank the following events in order from GREATEST to LEAST contribution to the spread of antibiotic resistance in bacterial populations.
horizontal transfer vertical transfer new mutations
Lysogeny can result in all of the following EXCEPT phage conversion. immunity to reinfection by the same phage. immunity to reinfection by any phage. acquisition of new characteristics by the host cell. specialized transduction.
immunity to reinfection by any phage.
If you wanted to evaluate a new disinfectant for effectiveness under the conditions of its intended use, the best evaluation technique would be the __________ test. phenol coefficient use-dilution Kelsey-Sykes capacity in-use
in-use
3. Differentiate between the terms incidence and prevalence.
incidence conveys information about the risk of contracting the disease, whereas prevalence indicates how widespread the disease is.
15. The minimum number of microbes required to cause diseases is the _______ ______.
infectious dose
In order to test if a chemical is a mutagen, you need to measure changes in the rate of DNA replication levels of reactive oxygen species (ROS) and DNA breaks cancer rates within a population its effect on mutation rate
its effect on mutation rate
Drug resistance
microorganisms begin to tolerate a drug
5. Define infectious dose, and explain its role in establishing infection.
minimum number of microbes required for an infection to proceed • Microbes with a smaller infectious dose have greater virulence (severity of disease)
8. The ________ rate is the number of persons afflicted with infectious disease.
morbidity
What does MDR mean? multi-directional radioactivity multi-drug-resistant minimal drug resistance map directed route
multi-drug-resistant
Polymyxin is effective against only some Gram-negative bacteria; therefore, it is considered a __________. host-specific drug intermediate-spectrum drug narrow-spectrum drug broad-spectrum drug
narrow-spectrum drug
A simple way to determine if gene mutations have occurred (changes in the genotype) is to observe a changes in a correlated phenotype treat the cells with radiation look at the DNA under a microscope make more mutations
observe a changes in a correlated phenotype
One approach that is becoming more common in drug D&D is to search for antimicrobial-producing organisms in relatively pristine environments. A pristine environment is one that has been relatively unperturbed by humans and/or domestic animals. Your D&D team is searching for novel antimicrobials produced by bacteria in a remote area of a temperate rainforest in the Pacific Northwest. Which of the following terms would accurately describe your drug? Select all that apply. natural chemotherapeutic agent synthetic semisynthetic antibiotic
natural chemotherapeutic agent antibiotic
DNA sequencing of an E. coli colony isolated from a nozzle that had biofilm growth of both bacteria shows that conjugation has occurred. However, the transformed strain of E. coli did not express any new proteins. BLAST analysis shows that the gene for the L. monocytogenes protein is incomplete in E. coli. Sequence comparison shows that E. coli has a truncated version of the gene that begins at nucleotide number 54 and continues to nucleotide 1257, meaning that no start codon is present. Why would this interfere with transcription or translation? Select all that apply. DNA bases are species specific no start codon for translation no promoter region for the transcription to begin at E. coli DNA polymerase does not recognize an L. monocytogenes gene sequence
no start codon for translation no promoter region for the transcription to begin at E. coli DNA polymerase does not recognize an L.
10. A _______ is an epidemic occurring over multiple continents.
pandemic
The first true antibiotic was __________, which was discovered by __________. penicillin; Alexander Fleming sulfanilamide; Gerhart Domagk streptomyces; Selman Waksman arsenic compounds; Paul Enrich
penicillin; Alexander Fleming
The ____________ is a defining characteristic of bacteria which is not found in eukaryotes and is therefore a good choice for chemotherapeutic agents. phospholipid cytoplasmic membrane steroid lipid cytoplasmic membrane peptidoglycan cell wall carbohydrate glycocalyx protein cell wall carbohydrate cell wall
peptidoglycan cell wall
Strachan's hypothesis not only includes fewer exposures to pathogens but also fewer exposures to everyday microbes that do not normally cause people to become ill. Exposure to which of the following microscopic substances will most likely lead to an allergy in an individual with an over reactive immune system? disinfectants viruses bacteria pollen
pollen
PCR stands for polymerase copy reaction. polymerase chain reaction. polymerization copying rapidly.
polymerase chain reaction.
A virus's ability to infect an animal cell depends primarily upon the enzymatic activity of a host cell. type of viral nucleic acid. host cell's ability to phagocytize viral particles. presence of receptor sites on the cell membrane. presence of pili on the host cell wall.
presence of receptor sites on the cell membrane.
7. The number of new cases of disease over a certain time period is the ________.
prevalence
Chloramphenicol blocks the action of the large (50S) subunit. This essentially _____. prevents the formation of peptide bonds changes the shape of the large subunit prevents a large subunit from attaching to a small subunit prevents the attachment of tRNA to a ribosome
prevents the formation of peptide bonds
Mutagens are useful in biotechnology research for producing DNA fragments for cloning. selecting genetic mutants resistant to radioactivity. removing undesirable traits from microbes. producing organisms with altered phenotypes. producing new organisms which have beneficial traits from two or more organisms.
producing organisms with altered phenotypes.
Which of the following enzymes can make specific cuts in DNA molecules? restriction enzymes DNA ligase DNA polymerase reverse transcriptase
restriction enzymes
Which drug for the treatment of tuberculosis inhibits RNA production and colors body secretions red-orange? polymyxin penicillin rifampin erythromycin
rifampin
Which type of HGT must involve a temperate phage? conjugation (chromosomal transfer) tranformation generalized transduction specialized transduction
specialized transduction
Mice that are injected with only the R strain of Streptococcus pneumoniae become sick for prolonged periods of time. are killed, because R strain cells are deadly. stay healthy, because their immune systems can kill this strain easily.
stay healthy, because their immune systems can kill this strain easily.
Strachan suggests that fewer exposures to childhood illnesses may lead to unintended consequences, including an increase in overreactions of the immune system (allergies). According to the readings in Chapter 9, which of the following is a chemical method to control the growth of microbes? radiation desiccation moist heat surfactants
surfactants
Which of the following activities can be shown to increase resistance among microbial populations? taking antibacterial drugs for viral infections taking a combination of antimicrobial drugs taking an antimicrobial drug for the entire prescribed time developing second- and third-generation versions of antimicrobial drugs
taking antibacterial drugs for viral infections
RNA polymerase is guided by the coding strand of DNA. template strand of DNA. RNA strand.
template strand of DNA.
When a transducing phage interacts with a new host cell, it will cause the new cell to produce more transducing phage. the new host cell will be lysed. the DNA from the previous host can recombine with the new host chromosome.
the DNA from the previous host can recombine with the new host chromosome.
When a transducing phage interacts with a new host cell, the new host cell will be lysed. it will cause the new cell to produce more transducing phage. the DNA from the previous host can recombine with the new host chromosome.
the DNA from the previous host can recombine with the new host chromosome.
Who was the most likely source of infection for this child? uncle grandmother sister mother
uncle
Retroviridae ("Retroviruses") are reverse transcribing viruses, therefore ___. infect the human nervous system use RNA as a template for DNA synthesis cause latent infections use a host polymerase for genome replication evolved in the 1960s
use RNA as a template for DNA synthesis
Which of the following procedures is currently the standard test used in the United States for evaluating the efficiency of antiseptics and disinfectants? phenol coefficient use-dilution test Kelsey-Sykes capacity test in-use test microbial death rate
use-dilution test
Which of the following classifications would best describe Candida albicans? protozoan yeast RNA virus bacteria
yeast
Some believe that if you drop a piece of food on the ground, you have approximately five seconds to pick it up and eat it. If you leave it longer than five seconds and eat it, you will likely become sick. In light of the "hygiene hypothesis," there may be some truth to the "Five-Second Rule." If one were to ascribe to the Five-Second Rule, which of the following places would be the most appropriate place to apply it? a library a school your home a hospital
your home
7. Compare and contrast major characteristics of exotoxins and endotoxin.
• Exotoxin: Secreted by a living bacterial cell to the infected tissues • Endotoxin: Not actively secreted, Cause fever and shock, Found shed from the outer membrane of gram-negative bacteria
1. Differentiate between a microbe's pathogenicity and its virulence.
• Pathogenicity: Describes an organism's potential to cause infection or disease • Virulence: The relative severity of the disease caused by a particular microorganism (determined by ability to establish/cause damage)
10. Differentiate among the various types of reservoirs, providing examples of each.
• Reservoir: a permanent place for an infectious agent to reside Animals- zoonotic infections Humans Non-living; soil, air, fomites
4. List several portals of entry and exit.
• Respiratory tract • Salivary glands • Urogenital tract • Skin cells • Fecal matter • Blood
