Exam 1 Test Files Flashcards by sophie rosen

What unique mechanism for transferring antibiotic resistance genes could occur at relatively high frequency for a
gene on a bacterial chromosome adjacent to a phage genome insertion site?
□ A: conjugation
□ B: transduction
□ C: transposition
□ D: integrin transfer □ E: transformation

□ B: transduction

How well did you know this?

Not at all

Perfectly

n testing antibiotic A by the disk diffusion assay, bacterium X has an inhibition zone of 10 mm. See the chart relating inhibition zone and antibiotic concentration. The drug safely achieves a concentration of 64-128 micrograms per milliliter in the human body. Which of the following is true?
□ A: The antibiotic will be effective against bacterium X in a patient
□ B: The antibiotic will be ineffective against bacterium X in a patient
□ C: It is not possible to tell from the above information if the antibiotic will be effective or not in a patient
□ D: The antibiotic will be effective at all concentrations >16 micrograms per milliliter in a patient
□ E: The antibiotic will be effective at all concentrations below 128 micrograms per milliliter in a patient

□ B: The antibiotic will be ineffective against bacterium X in a patient

How well did you know this?

Not at all

Perfectly

Which anti-mycobacterial antibiotic acts by inhibiting the attachment of mycolic acid to the cell wall?
□ A: Metranidazole 
□ B: Isoniazid
□ C: Ethambutol 
□ D: Cycloserine
□ E: Trimethoprim

□ C: Ethambutol

How well did you know this?

Not at all

Perfectly

4 What is a common mechanism of bacterial resistance to tetracyclines?
□ A: hydrolysis of -lactam ring by -lactamase
□ B: drug-resistant dihydrofolate reductase
□ C: drug-resistant dihydropteroate synthase
□ D: methylation of 23S rRNA
□ E: activation/acquisition of a drug efflux pump

□ E: activation/acquisition of a drug efflux pump

How well did you know this?

Not at all

Perfectly

Import of glucose into bacterial cells
□ A: uses a permease to facilitate movement of glucose across the plasma membrane
□ B: involves chemical alteration of glucose as part of the transport process
□ C: only occurs if the glucose can move passively down a concentration gradient
□ D: uses a proton gradient in the import process
□ E: requires a siderophore

□ B: involves chemical alteration of glucose as part of the transport process

How well did you know this?

Not at all

Perfectly

Which oral bacteria are facultative anaerobes?
□ A: Aggregatibacter spp. 
□ B: Neisseria spp.
□ C: Eubacterium spp.
□ D: Streptococcus spp.
□ E: Propionibacterium spp.

□ D: Streptococcus spp.

How well did you know this?

Not at all

Perfectly

Which of the following elements is often required as a cofactor for specific enzymes?
□ A: carbon
□ B: phosphorus 
□ C: sulfur
□ D: nitrogen
□ E: zinc

□ E: zinc

How well did you know this?

Not at all

Perfectly

Which is an example of a bacterial genus whose members require a complex nutrient source such as blood agar
for growth in the laboratory? 
□ A: Chlamydia
□ B: Pseudomonas
□ C: Streptococcus
□ D: Lactobacillus □ E: Escherichia

□ C: Streptococcus

How well did you know this?

Not at all

Perfectly

A cell has abundant levels of tryptophan and, as a consequence, stops transcription of genes for tryptophan
biosynthesis through the binding of a protein to the operator site adjacent to these genes. This is an example of
□ A: attenuation
□ B: allosteric regulation
□ C: gene repression by a corepressor
□ D: gene induction by an inducer □ E: group translocation

□ C: gene repression by a corepressor

How well did you know this?

Not at all

Perfectly

Fimbriae
□ A: are numerous (up to 1000/cell) short, thin, hairlike, proteinaceous appendages on a bacterial cell s surface
□ B: are long, thick, proteinaceous appendages on a bacterial cellʝs surface numbering only 1-10/cell
□ C: are networks of polysaccharides that coat bacterial cells
□ D: provide bacteria protection from osmotic stress
□ E: are composed of substructures called a filament, a basal body, and a hook

□ A: are numerous (up to 1000/cell) short, thin, hairlike, proteinaceous appendages on a bacterial cell s surface

How well did you know this?

Not at all

Perfectly

Which is a property of saliva?
□ A: salivary components are similar to serum within the blood stream
□ B: salivary components compete with bacteria for binding tooth surfaces
□ C: salivary components promote aggregation of bacteria
□ D: saliva causes large pH changes in oral cavity
□ E: saliva is the main source of neutrophils in oral cavity

□ C: salivary components promote aggregation of bacteria

How well did you know this?

Not at all

Perfectly

What component is only found in gram-positive bacteria?
□ A: Braun s lipoprotein 
□ B: lipopolysaccharide
□ C: flagella
□ D: peptidoglycan
□ E: capsule

□ A: Braun s lipoprotein

How well did you know this?

Not at all

Perfectly

What is false about the cells growing on the petri dish in step 7 of the scheme depicted in figure 4-3?
□ A: they contain one or more Yersinia pseudotuberculosis genes
□ B: they contain a complete E. coli genome
□ C: they are bacteria that had invaded the mammalian cells
□ D: they are bacteria that contain an insertion mutation
□ E: they are bacteria that can be killed if exposed to gentamycin

□ D: they are bacteria that contain an insertion mutation

How well did you know this?

Not at all

Perfectly

What is a property of a bacterial slime layer? protects a bacterium from viral infection or predation by other
bacteria and is typically composed exclusively of polysaccharides?
□ A: typically composed of lipids
□ B: typically composed of proteins
□ C: typically composed of chains of N-acetylglucosamine plus N-acetylmuramic acid
□ D: typically composed of polysaccharides
□ E: typically composed of nucleic acids

□ D: typically composed of polysaccharides

How well did you know this?

Not at all

Perfectly

What is a false statement about the bacterial component of a typical human microbiome?
□ A: there are 10 times more bacterial cells than human cells
□ B: bacteria comprise up to ~3% of a person’s body weight
□ C: these bacteria interfere with our immune system’s ability to recognize pathogenic bacteria
□ D: we begin acquire these bacteria after birth
□ E: these bacteria are not typically present in cerebrospinal fluid

□ C: these bacteria interfere with our immune system’s ability to recognize pathogenic bacteria

How well did you know this?

Not at all

Perfectly

What is the most likely example of an exogenously acquired disease?
□ A: HIV/AIDS acquired in utero
□ B: common cold from a rhinovirus infection
□ C: staphylococcal infection from a cut in the skin
□ D: pneumonia from microaspirations of Pneumococcus bacteria
□ E: uninary tract infection by E. coli

□ B: common cold from a rhinovirus infection

How well did you know this?

Not at all

Perfectly

Why is “gentle lysis” used for in step 6 of the scheme depicted in figure 4-3?
□ A: to kill E. coli cells that are present outside of mammalian cells
□ B: to select for E. coli cells that contain a suicide plasmid
□ C: to liberate E. coli cells that are present inside of mammalian cells
□ D: to select for E. coli cells that contain a transposon insertion □ E: to promote the invasion of mammalian cells by E. coli

□ C: to liberate E. coli cells that are present inside of mammalian cells

How well did you know this?

Not at all

Perfectly

1/1
18 Where in the oral cavity would you expect to find the largest numbers of
neutrophils? 
□ A: saliva
□ B: dorsum of tongue
□ C: buccal mucosa
□ D: gingival crevicular fluid
□ E: where dental appliances contact
teeth

□ D: gingival crevicular fluid

How well did you know this?

Not at all

Perfectly

What component of bacterial cells is most significant in conferring cell shap etc.)?
□ A: plasma membrane
□ B: lipopolysaccharrides
□ C: peptidoglycan layer
□ D: capsule
□ E: inclusion bodies

□ C: peptidoglycan layer

How well did you know this?

Not at all

Perfectly

What is the main phosphorus source for bacteria?
□ A: amino acids
□ B: ammonia
□ C: glucose-6- phosphate
□ D: phosphoenolpyruvate (PEP)
□ E: inorganic phosphate

□ E: inorganic phosphate

How well did you know this?

Not at all

Perfectly

20 Which molecules anchor the peptidoglycan layer to the plasma membrane of gram positive bacteria?
□ A: lipoteichoic acids
□ B: siderophores
□ C: lipopolysaccharides
□ D: hopanoids
□ E: Braun's lipoproteins

□ A: lipoteichoic acids

How well did you know this?

Not at all

Perfectly

Which oral bacteria require significant amounts of carbon dioxide for opti growth?
□ A: Capnocytophaga spp. 
□ B: Neisseria spp.
□ C: Eubacterium spp.
□ D: Veillonella spp.
□ E: Actinomyces spp.

□ A: Capnocytophaga spp.

How well did you know this?

Not at all

Perfectly

Which of the following are cholesterol-like molecules present in bacterial membranes?
□ A: teichoic
acids
□ B: siderophores
□ C: lipopolysaccharides
□ D: hopanoids 
□ E: Braun's
lipoproteins

□ D: hopanoids

How well did you know this?

Not at all

Perfectly

What life style do all microbial pathogens engage in?
□ A: Photoorganotrophic heterotrophy
□ B: Photolithotrophic autotrophy
□ C: Chemoorganotrophic heterotrophy
□ D: Chemolithotrophic
autotrophy
□ E: Chemophototrophic heteroorganotrophy

□ C: Chemoorganotrophic heterotrophy

How well did you know this?

Not at all

Perfectly

What life style uses a chemical energy source, an inorganic electron donor, and carbon dioxide as a carbon source? □ A: Photoorganotrophic heterotrophy □ B: Photolithotrophic autotrophy □ C: Chemoorganotrophic heterotrophy □ D: Chemolithotrophic autotrophy □ E: Chemophototrophic heteroorganotrophy

□ D: Chemolithotrophic autotrophy

In the in vivo induced antigen technology scheme (IVIAT, figure 4-11), what would ideally occur in step 4 when using serum from a tuberculosi processed as outline in the figure? □ A: Antibodies would not bind and no signal would be generated from any of the phage plaque replicates □ B: Antibodies would bind to the entire replica filter, generating signal from the entire filter surface, making individual phage plaques indistinguishable □ C: Antibodies would bind to each phage plaque replicate, generating signal from all of plaques, which would appear as black spots at the positions of th plaques □ D: Antibodies would only bind to phage plaque replicates that express mycobacterial proteins expressed on the bacterial cell surface within generating signal from just a few spots □ E: No antibodies of any type would be present for use in step 4

□ D: Antibodies would only bind to phage plaque replicates that express mycobacterial proteins expressed on the bacterial cell surface within generating signal from just a few spots

In the microarray scheme (figure 4-12), what would be the signal for a gene that is expressed at a higher level in V. cholerae during growth in th compared to growth during an infection? □ A: no fluorescent signal since the signals from each labeled DNA sample will cancel each other out □ B: no fluorescent signal since the procedure only detects fluorescence if genes are expressed at higher levels during infection □ C: a yellow fluorescent signal (equal levels of Cy3 and Cy5 fluorescence) □ D: a red fluorescent signal (Cy5 fluorescence greater than Cy3 fluorescence) □ E: a green fluorescent signal (Cy3 fluorescence greater than Cy5 fluorescence)

□ D: a red fluorescent signal (Cy5 fluorescence greater than Cy3 fluorescence)

In signature-tagged mutagenesis (figure 4-8),which of the following is a correct statement about the blank spots in the recovered pool blot? □ A: the blank spots represent Salmonella mutants that lost the kanamycin resistance gene during growth in the mouse □ B: the blank spots represent Salmonella mutants that survived in mice □ C: the blank spots represent Salmonella mutants that lost their DNA sequence tags (variable region) during growth in the mouse □ D: the blank spots represent Salmonella mutants that did not grow in mice and, therefore, these mutants represent specific genes necessa virulence □ E: the blank spots represent Salmonella mutants that were not present in the input pool of bacteria

□ D: the blank spots represent Salmonella mutants that did not grow in mice and, therefore, these mutants represent specific genes necessa virulence

n the microarray scheme (figure 4-12), what would be the signal for "housekeeping” gene that is expressed at the same level in V. cholerae during an infection and during growth in the laboratory? □ A: no fluorescent signal since the signals from each labeled DNA sample will cancel each other out □ E: a green fluorescent signal (Cy3 fluorescence greater than Cy5 fluorescence) □ B: no fluorescent signal since the microarray does not contain housekeeping gene □ D: a red fluorescent signal (Cy5 fluorescence greater than Cy3 fluorescence) sequences 1/1 □ C: a yellow fluorescent signal (equal levels of Cy3 and Cy5

□ C: a yellow fluorescent signal (equal levels of Cy3 and Cy5 ????

In the in vivo induced antigen technology scheme (IVIAT, figure 4-11), what would occur if step 3 were not performed and the original, unmodified patient serum sample was used for step 4. □ A: Antibodies would not bind and no signal would be generated from any of the phage plaque replicates □ B: Antibodies would bind to the entire replica filter, generating signal from the entire filter surface, making individual phage plaques indistinguishable □ C: Antibodies would bind to each phage plaque replicate, generating signal from all of plaques, which would appear as black spots at the positions of all the phage plaques □ D: Antibodies would only bind to phage plaque replicates that express mycobacterial proteins expressed on the bacterial cell surface within the patien generating signal from just a few spots, just as shown in figure 4-11 □ E: No antibodies would be present for use in step 4

□ B: Antibodies would bind to the entire replica filter, generating signal from the entire filter surface, making individual phage plaques indistinguishable

In the in vivo expression technology method to identify virulence genes (IVET, figure 4-9), what is a function of the ampicillin resistance gene on the plasmid? □ A: to select for Salmonella bacteria that contain the plasmid inserted within their genome □ B: to identify candidate virulence genes that are not expressed during laboratory growth □ C: to identify candidate virulence genes that are transcriptionally active in the mouse □ D: to prevent growth of E. coli cells containing the pIVET1 plasmid □ E: to allow growth of Salmonella bacteria within the mouse

□ A: to select for Salmonella bacteria that contain the plasmid inserted within their genome

Which of the following is a correct statement about signature-tagged mutagenesis (figure 4-8)? □ A: the kanamycin resistance gene is the tag used to compare the input and recovered pools of bacteria □ B: the kanamycin resistance gene helps the bacteria to survive in mice □ C: the DNA sequence tags (variable region) are used to compare the input and recovered pools of bacteria □ D: the dark spots in the recovered pool blot represent bacterial mutants that grew in mice and, therefore, these mutants represent specific genes nece for virulence □ E: the input pool of bacteria is a mixture of bacterial cells, some of which are kanamycin-resistant and some of which are kanamycin-sensitive

□ C: the DNA sequence tags (variable region) are used to compare the input and recovered pools of bacteria

What is the basis of the antibiotic activity of rifampin? □ A: the drug binds to the 50S subunit and inhibits peptidyltransferase activity □ B: the drug binds to the 23S rRNA in the 50S subunit, preventing formation of the 70S ini complex □ C: the drug binds to the 30S subunit and distorts the A site, causing translation misreading □ D: the drug binds to the 16S rRNA of the 30S subunit, preventing binding of aa-tRNA to A site □ E: the drug binds to bacterial RNA polymerase, preventing initiation of transcription

□ E: the drug binds to bacterial RNA polymerase, preventing initiation of transcription

Which of the following is an correct statement related to the white colonies at step 2 in the Tn-phoA mutagenesis scheme depicted in figure 4-7? □ A: the PhoA enzyme is expressed outside of the bacterial cells □ B: the ᵻpho gene is fused to a Vibrio cholera gene that encodes a secreted protein □ C: the engineered transposon is not present within cells in the white colonies □ D: the PhoA enzyme is synthesizing a colored molecule inside bacterial cells □ E: the pho gene is not fused to a Vibrio cholera gene that encodes a secreted protein

□ E: the pho gene is not fused to a Vibrio cholera gene that encodes a secreted protein

What is the basis of the antibiotic activity of oxazolidinones? □ A: the drug binds to the 50S subunit and inhibits peptidyltransferase activity □ B: the drug binds to the 23S rRNA in the 50S subunit, preventing formation of the 70S ini □ C: the drug binds to the 30S subunit and distorts the A site, causing translation misreading □ D: the drug binds to the 16S rRNA of the 30S subunit, preventing binding of aa-tRNA to A site □ E: the drug binds to bacterial RNA polymerase, preventing initiation of transcription

□ B: the drug binds to the 23S rRNA in the 50S subunit, preventing formation of the 70S ini

Which antibiotic binds the terminal D-Ala-D-Ala of peptide side chains of peptidoglycan subunits, sterically inhibiting addition of new subunits to the cell wall? □ A: chloramphenicol □ B: cycloserine □ C: vancomycin □ D: tetracycline □ E: bacitracin

□ C: vancomycin

How does ciprofloxacin act as an antibiotic? □ A: binds a human topoisomerase and prevents it from being used by bacteria □ B: binds some types of double strand breaks in bacterial DNA and prevents their repair □ C: binds some types of double strand breaks in human DNA and prevents their repair □ D: binds bacterial RNA and prevents translation □ E: binds the bacterial 50S ribosomal subunit and prevents the peptidyltransferase reaction

□ B: binds some types of double strand breaks in bacterial DNA and prevents their repair

``` Which of the following antibiotic inhibits folic acid synthesis? □ A: Dapsone □ B: Isoniazid □ C: Ethambutol □ D: Cycloserine □ E: Trimethoprim ```

□ A: Dapsone

Which is true about the antibacterial compound tazobactam? □ A: it is a beta-lactam compound □ B: it blocks the joining of peptidoglycan subunits to the peptidoglycan network □ C: it is a beta lactamase □ D: it is cephalosporin □ E: it is a beta-lactamase inhibitor

□ E: it is a beta-lactamase inhibitor

A potential antibiotic is found to have a ratio of 0.01 for the toxic dose relative to the therapeutic dose. Which of the following is true? □ A: the therapeutic index is 1000 □ B: the therapeutic index is 0.01 □ C: the drug is definitely not safe for use in patients □ D: the therapeutic index suggests the drug is safe and effective □ E: the drug has a zone of inhibition of 100mm

□ B: the therapeutic index is 0.01

What is an example of an endgenously acquired disease?

A: pneumonia

What class of nutrient uptake system in bacteria uses permeases to move substances from higher to lower concentration, without energy input?

A: facilitated diffusion

What is the role of MHC molecules in the recognition of infected cells by NK cells, and what is the physiological recognition?

A: MHC molecules are expressed by "self cells", bind to the inhibitor recpeotr on NK and tell the NK to not kill these cells. If this molecule is missing then the inhibitor receptor is not activated and NK know that it is a foreign cell and lysis is induced.

``` What are 3 classes of innate immunity receptors and give an example of a microbial substance recognized by each class of receptor. ```

? A: Toll-like receptors - extracellular PAMPs (ex: bacterial flagella) Nod-like receptors - intracellular DAMPs or PAMPS (parts of ingested microbes) rig-like receptors - intracellular viruses (pieces of ingested viruses) TOLL: PAMPs RIG: viral RNA NOD: PAMPs and DAMPs

How does the specificity of innate immunity differ from that of adaptive immunity?

A: adaptive is highly specific, | whereas innate is not

What are the 2 types of adaptive immunity and what types of microbes do these adaptive immune responses combat?

A: humoral and cell-mediated immunity. humoral combats extracellular microbes and cell-mediated combats phagocytosed microbes and virus-infected cells.

Where are T and B lymphocytes located in lymph nodes and how is anatomical separation accomplished? (2 points)

A: T lymphocytes are located in the parafollicular cortex of the lymph node and b cells are located in the follicle. The anatomical separation is maintained through expression of cytokines specific to b and t cells in the areas that they are restricted to.

What are the 4 principal classes of lymphocytes and list an effector function for each class.

A: B lymphocytes - humoral immunity through antibody production Helper T lymphocytes - recognize dendritic APC's and release cytokines to induce immune response Cytotoxic T lymphocytes - release enzymes within an infected cell to induce lysis Regulatory T lymphocytes - protect our self cells by suppressing our own immune response to them

What is a common mechanism of bacterial resistance to quinolones? (1 point) Name another specific mechanism of bacterial antibiotic resistance of your choice. (1 point)

A: bacteria will mutate their DNA gyrase or their topoisomerases to resist quinolones. bacteria will use an efflux pump to resist tetracyclines.

What is the mechanism of action of the antibiotic chloramphenicol?

A: binds the 50S subunit of the ribosome and prevents the | peptidyltransferase reaction from occurring

What is the mechanism of action of the antibiotic penicillin? (1 point)

A: mimics the d-ala d-ala linkage and inhibits transpeptidation of the Peptidoglycan structure

Name the 3 ways that antibiotic resistance genes can be transferred at high frequency from one bacterium to another? (3 points)

A: conjugation, transduction, and transposition

Describe the key components of Augmentin in treating a bacterial infection. (2 points)

A: Augmentin is a mixture of amoxicillin and clavulanic acid. This is a mixture of a B-lactam penicillin that will mimic the d-ala d-ala bond and inhibit transpeptidation, with a b-lactamase inhibitor that overcomes the bacterial resistance mechanism of b-lactamase.

A: This drug is right on the border of being resistant, to being ineffective. So overall this drug will not be effective in treating bacterium X.

What are 3 factors that influence the ability of an antibiotic to reach its minimal inhibitory concentration in a patient? (3 points)

A: The amount of the drug that is given, its rate of clearance from the body, and its rate of uptake into the bacteria or cell

Define the therapeutic index for an antibiotic? (1 point)

A: the ratio of the toxic dose to the therapeutic dose of an antibiotic

In the in vivo expression technology method to identify virulence genes (IVET, figure 4-9), what is a function of the purA gene on the plasmid? (1 point)

To look for genes of S. typhimurium that are expressed during infection ? NOT A: Having the PurA gene on the plasmid will allow the bacteria to to be virulent in vivo and show you whether or not salmonella growth was able to occur in the spleen of the mouse.

In the microarray scheme (figure 4-12), what would be the fluorescence characteristic of the signal for a gene that is expressed at a higher level in V. cholerae during growth in the laboratory compared to growth during an infection? (1 point)

A: Cy5-labeled and red fluorescence

With respect to the goals of the experimental plan, what are the most important properties of a transposon insertion in bacteria in a dark colony at step 2 in the Tn-phoA mutagenesis scheme depicted in figure 4-7? (2 points)

ORF promoter upstream of 'phoA ? NOT A: The dark colonies are PhoA+, are producing alkaline phosphatase, and therefore we know that they possess our transposon 20

With respect to the goals of the experimental plan, what is the important property of the cells growing on the petri dish in step 7 of the scheme depicted in figure 4-3? (1 point)

A: These cells are E. coli that were able to invade mammalian cells and therefore have acquired the invasin gene

What is gentamicin used for in step 5 of the scheme depicted in figure 4-3? (1 point)

A: washes away any E. Coli that did not invade the mammalian cells, therefore washes away the E. coli that did not receive the invasin gene

In the in vivo induced antigen technology scheme (IVIAT, figure 4-11), what happens in step 4 when using serum from a tuberculosis patient that has been processed as outline in the figure? (1 point)

? NOT A: in step 4, we see dark spots in those spots where the Tb antibody was present

In signature-tagged mutagenesis (figure 4-8) (1) what do the blank areas in the recovered pool blot represent and (2) are they of interest or not of interest for further study to the researchers and (3) why? (3 points)

A: Blank spots show spots in the genome where virulence was knocked out and we see anti-virulence. They are of interest because it can tell you that that transposon "hopped" into the spot of a virulence factor and possibly where in the genome virulence factors are located.

In step 4 of figure 4-10, why are bacterial cells run through the fluorescence activated cell sorter? (1 point)

A: this shows whether or not they fluoresce in vitro (which we only are looking for fluorescence in vivo)

A cell has abundant levels of tryptophan and, as a consequence, decreases the production of an enzyme for tryptophan biosynthesis by preventing initiation of transcription of the mRNA for the enzyme. What is the role of tryptophan in this type of regulation, as discussed in class? (1 point)

A: Tryptophan acts as a corepressor to activate the repressor in this situation

What is the main phosphorus source for bacteria? (1 point)

A: inorganic phosphate

Name a nutrient brought into a bacterial cell by group translocation and describe a key feature of this mode of import. (2 points)

A: Glucose is brought into the cell by group translocation, in which it is modified to be glucose-6-phosphate.

28 Name an oral bacterial genus whose members are strict anaerobes? (1 point)

A: Prevotella

Regarding organism lifestyles, as discussed in class, what 3 lifestyle features are described by the term chemoorganotrophic heterotrophy? (3 points)

A: organic or inorganic energy source organic electron donor organic carbon source

``` A cell has abundant levels of tryptophan and, as a consequence, decreases the activity of an enzyme for tryptophan biosynthesis through the binding of tryptophan itself to a site on the enzyme that is not the active site. (1) What class of enzyme is subject to such feedback regulation and (2) what is one possible way the binding of tryptophan to the enzyme can result in a change in enzymatic activity? (2 points) ```

A: This is an example of allosteric regulation. One way that tryptophan binding to the enzyme can change enzymatic activity by changing the vmax of the reaction to slow the production of enzymes for tryptophan biosynthesis.

31 Name the 3 structural components of a peptidoglycan subunit. (3 points)

NAG, NAM, crosslinked peptide chains ? 2/3 A: NAG, NAM, phosphate bond

What component of bacterial cells is the most significant in conferring cell shape (rod, spiral, etc.)? (1 point)

A: Cell wall

Name 3 properties of saliva, as discussed in class. (3 points)

A: promotes bacterial aggregation, maintains pH, promotes pellicle formation on tooth surfaces

Name 3 properties of bacterial LPS, as presented in class. (no credit for stating something to the effect that it is bacterial – I need more detail) (3 points)

A: bacterial LPS have an o antigen, a core polysaccharide, and a lipid A portion.

What are 3 nutritional macroelements required for building cell components? (3 points)

A: Carbon, oxygen, nitrogen

36 Which fluid of the oral cavity has a composition similar to serum within the blood stream? (1 point)

A: Gingival crevicular fluid

What is the approximate quantity of bacteria of a typical human microbiome (percentage of a person’s weight composed of bacteria OR the number of bacterial cells relative to the number of the person’s cells)?

A: there are 10X more bacteria than human cells

What are the long, thick, proteinaceous appendages produced on a bacterial cell’s surface numbering only 1- 10/cell, through which DNA can be transferred to another bacterium? (1 point)

A: sex pili

39 What specific type of cells have teichoic acid as a cell wall component? (1 point)

A: gram + bacteria

What cells have teichoic acid as a cell wall component? X A: gram-negative bacteria X B: gram-positive bacteria X C: human cells X D: some eukaryotic microbes X E: all spore-forming bacteria

> B: gram-positive bacteria

Which of the following molecules densely project from the surfaces of most gram negative bacteria? ``` X A: teichoic acids X B: siderophores X C: lipopolysaccharides X D: hopanoids X E: Braun's lipoproteins ```

> C: lipopolysaccharides

What is a not property associated with the normal bacterial flora of a human body? X A: detoxification of carcinogens X B: occupies space to crowd out disease-causing microbes X C: produces some vitamins that we do not have the genes to make X D: begins to accumulate in utero X E: teaches our immune systems how to recognize dangerous invaders

X D: begins to accumulate in utero

Which is true of peptidoglycan? X A: the peptide component is translated by the ribosome X B: the peptide component of peptidoglycan is linked to N-acetylglucosamine X C: it is polysaccharide layer that promotes movement of gliding bacteria X D: it forms a thin layer in gram negative bacteria compared to gram positive bacteria X E: it is a precursor to teichoic acid

X D: it forms a thin layer in gram negative bacteria compared to gram positive bacteria

Which is a property of saliva? X A: composition is similar to serum within the blood stream X B: flushes bacteria out of gingival crevice X C: promotes aggregation of bacteria X D: responsible for pH changes in oral cavity X E: contains high numbers of neutrophils

X C: promotes aggregation of bacteria

Where in the oral cavity would you expect to find the largest numbers of neutrophils? ``` X A: saliva X B: dorsum of tongue X C: buccal mucosa X D: gingival crevicular fluid X E: where dental appliances contact teeth ```

X D: gingival crevicular fluid

Fimbriae X A: are numerous (up to 1000/cell) short, thin, hairlike, proteinaceous appendages on a bacterial cells surface X B: are long, thick, proteinaceous appendages on a bacterial cells surface numbering only 1-10/cell X C: are networks of polysaccharides that coat bacterial cells X D: provide bacteria protection from osmotic stress X E: are composed of substructures called a filament, a basal body, and a hook

X A: are numerous (up to 1000/cell) short, thin, hairlike, proteinaceous appendages on a bacterial cells surface

What is the most likely example of an exogenously acquired disease? X A: HIV/AIDS acquired in utero X B: common cold from a rhinovirus infection X C: staphylococcal infection from a cut in the skin X D: pneumonia from microaspirations of Pneumococcus bacteria X E: uninary tract infection by E. coli

> B: common cold from a rhinovirus infection

Allosteric regulation can directly result in X A: termination of transcription X B: binding of a repressor protein to an operator site X C: an increase in transcription X D: change in the Vmax of an enzyme X E: removal of a repressor protein to an operator site

X D: change in the Vmax of an enzyme

Which of the following is not an example of a nutritional macroelement required for building cell components? ``` X A: oxygen X B: hydrogen X C: phophorus X D: sulphur X E: zinc ```

X E: zinc

Which is a typical sulfur source for bacterial cells? ``` X A: sulfate X B: sulfur dioxide X C: hydrogen sulfide X D: sulfanilamide X E: methionine ```

X A: sulfate

Which is an example of a bacterial genus whose members are so limited in their ability to exploit environmentally available compounds as carbon and energy sources that they have adopted an obligate intracellular lifestyle? ``` X A: Chlamydia X B: Pseudomonas X C: Staphylococcus X D: Streptococcus X E: Escherichia ```

X A: Chlamydia

What life style do all microbial pathogens engage in? ``` X A: Photoorganotrophic heterotrophy X B: Photolithotrophic autotrophy X C: Chemoorganotrophic heterotrophy X D: Chemolithotrophic autotrophy X E: Chemophototrophic heteroorganotrophy ```

> C: Chemoorganotrophic heterotrophy

A cell has abundant levels of tryptophan and, as a consequence, stops transcription of genes for tryptophan biosynthesis through the binding of a protein to the operator site adjacent to these genes. This is an example of ``` X A: attenuation X B: allosteric regulation X C: gene repression by a corepressor X D: gene induction by an inducer X E: group translocation ```

X C: gene repression by a corepressor

Import of glucose into bacterial cells X A: uses a permease to facilitate movement of glucose across the plasma membrane X B: involves chemical alteration of glucose as part of the transport process X C: only occurs if the glucose can move passively down a concentration gradient X D: uses a proton gradient in the import process X E: requires a siderophore

X B: involves chemical alteration of glucose as part of the transport process

A cell is exposed to lactose and, as a consequence, increases the production of enzymes for lactose utilization by increasing initiation of transcription of the mRNA for the enzymes. This is an example of ``` X A: attenuation X B: allosteric regulation X C: gene repression by a corepressor X D: gene induction by an inducer X E: group translocation ```

X D: gene induction by an inducer

What is gentamicin used for in step 5 of the scheme depicted in figure 4-3? X A: to kill E. coli cells that are present outside of mammalian cells X B: to select for E. coli cells that contain a suicide plasmid X C: to liberate E. coli cells that are present inside of mammalian cells X D: to select for E. coli cells that contain a transposon insertion X E: to promote the invasion of mammalian cells by E. coli

X A: to kill E. coli cells that are present outside of mammalian cells

In signature-tagged mutagenesis (figure 4-8),which of the following is a correct statement about the blank spots in the recovered pool blot? X A: the blank spots represent Salmonella mutants that lost the kanamycin resistance gene during growth in the mouse X B: the blank spots represent Salmonella mutants that survived in mice X C: the blank spots represent Salmonella mutants that lost their DNA sequence tags (variable region) during growth in the mouse X D: the blank spots represent Salmonella mutants that did not grow in mice and, therefore, these mutants represent specific genes necessary for virulence X E: the blank spots represent Salmonella mutants that were not present in the input pool of bacteria

X D: the blank spots represent Salmonella mutants that did not grow in mice and, therefore, these mutants represent specific genes necessary for virulence

In step 5 of figure 4-10, why are bacterial cells reintroduced into macrophages and run through the fluorescence activated cell sorter? X A: to retest bacterial cells that fluoresced on their own because these are the bacteria of interest X B: to identify bacterial cells that fluoresce within macrophages from the bacterial cell population that also fluoresced when growing on their own in a lab environment, since these are the bacteria of interest X C: to create a pure population of bacteria that do not fluoresce when within macrophages, since these are the bacteria of interest X D: to identify bacterial cells that fluoresce within macrophages from the bacterial cell population that did not fluoresce when growing on their own in a lab environment, since these are the bacteria of interest X E: the researchers are seeking any bacterial gene fusion that expresses green fluorescent protein (gfp), whether in the lab environment or within macrophages

X D: to identify bacterial cells that fluoresce within macrophages from the bacterial cell population that did not fluoresce when growing on their own in a lab environment, since these are the bacteria of interest

In the in vivo expression technology method to identify virulence genes (IVET, figure 4-9), what is a function of the ampicillin resistance gene on the plasmid? X A: to select for Salmonella bacteria that contain the plasmid inserted within their genome X B: to identify candidate virulence genes that are not expressed during laboratory growth X C: to identify candidate virulence genes that are transcriptionally active in the mouse X D: to prevent growth of E. coli cells containing the pIVET1 plasmid X E: to allow growth of Salmonella bacteria within the mouse

X A: to select for Salmonella bacteria that contain the plasmid inserted within their genome

In the microarray scheme (figure 4-12), what would be the signal for a housekeeping gene that is expressed at the same level in V. cholerae during an infection and during growth in the laboratory? X A: no fluorescent signal since the signals from each labeled DNA sample will cancel each other out X B: no fluorescent signal since the microarray does not contain housekeeping gene sequences X C: a yellow fluorescent signal (equal levels of Cy3 and Cy5 fluorescence) X D: a red fluorescent signal (Cy5 fluorescence greater than Cy3 fluorescence) X E: a green fluorescent signal (Cy3 fluorescence greater than Cy5 fluorescence)

X C: a yellow fluorescent signal (equal levels of Cy3 and Cy5 fluorescence)

Which of the following is an correct statement related to the white colonies at step 2 in the Tn-phoA mutagenesis scheme depicted in figure 4-7? X A: the PhoA enzyme is expressed outside of the bacterial cells X B: the pho gene is fused to a Vibrio cholera gene that encodes a secreted protein X C: the engineered transposon is not present within cells in the white colonies X D: the PhoA enzyme is synthesizing a colored molecule inside bacterial cells X E: the pho gene is not fused to a Vibrio cholera gene that encodes a secreted protein

X E: the pho gene is not fused to a Vibrio cholera gene that encodes a secreted protein

Which of the following is true about the RNA sequencing (RNA-seq) method for identifying bacterial virulence factors? X A: RNA-seq is less sensitive than microarray analysis X B: RNA-seq can be performed on impure samples that contain multiple bacterial species as well as host cells X C: RNA-seq was used to identify genomic regions that are unique to pathogenic E. coli O157:H7 and not present in non- pathogenic strains X D: RNA-seq does not depend on knowing the genome sequence of the pathogen of interest

X B: RNA-seq can be performed on impure samples that contain multiple bacterial species as well as host cells

In the in vivo induced antigen technology scheme (IVIAT, figure 4-11), what would occur if step 3 were not performed and the original, unmodified patient serum sample was used for step 4. X A: Antibodies would not bind and no signal would be generated from any of the phage plaque replicates X B: Antibodies would bind to the entire replica filter, generating signal from the entire filter surface, making individual phage plaques indistinguishable X C: Antibodies would bind to each phage plaque replicate, generating signal from all of plaques, which would appear as black spots at the positions of the all the phage plaques X D: Antibodies would only bind to phage plaque replicates that express mycobacterial proteins expressed on the bacterial cell surface within the patient, generating signal from just a few spots, just as shown in figure 4-11 X E: No antibodies would be present for use in step 4

X B: Antibodies would bind to the entire replica filter, generating signal from the entire filter surface, making individual phage plaques indistinguishable

For a useful antibiotic, the therapeutic index X A: must be greater than 1000 X B: is equal to 1 X C: must be less than 1 X D: can be greater than 1, equal to 1, or less than 1 depending on the antibiotic X E: must be significantly greater than 1 but can be as low as 2 for some drugs

X E: must be significantly greater than 1 but can be as low as 2 for some drugs

What is meant by the therapeutic index for an antibiotic? X A: minimal inhibitory concentration (MIC) X B: minimal bacteriocidal concentration (MBC) X C: the ratio of the toxic dose to the therapeutic dose X D: the ratio of the therapeutic dose to the toxic dose X E: the ratio of the zone of inhibition to the drug concentration in the body

X C: the ratio of the toxic dose to the therapeutic dose

In testing antibiotic A by the disk diffusion assay, bacterium X has an inhibition zone of 14 mm. See the chart relating inhibition zone and antibiotic concentration. The drug safely achieves a concentration of 8-16 micrograms per milliliter in the human body. Which of the following is true? X A: The antibiotic will be effective against bacterium X in a patient X B: The antibiotic will be ineffective against bacterium X in a patient X C: It is not possible to tell from the above information if the antibiotic will be effective or not in a patient X D: The antibiotic will be effective at all concentrations <16 micrograms per milliliter in a patient X E: The antibiotic will be effective at all concentrations >8 micrograms per milliliter in a patient

X B: The antibiotic will be ineffective against bacterium X in a patient

What unique mechanism for transferring antibiotic resistance genes could occur at relatively high frequency for a gene on a bacterial chromosome adjacent to a phage genome insertion site? X A: conjugation X B: transduction X C: transposition X D: integrin transfer X E: transformation

X B: transduction

What is a common mechanism of bacterial resistance to tetracyclines? 29 X A: hydrolysis of -lactam ring by -lactamase X B: drug-resistant dihydrofolate reductase X C: drug-resistant dihydropteroate synthase X D: methylation of 23S rRNA X E: activation/acquisition of a drug efflux pump

X E: activation/acquisition of a drug efflux pump

Which of the following compounds are not beta-lactam antibiotics? ``` X A: carbapenems X B: penicillins X C: tetracyclines X D: cephalosporins X E: monobactams ```

X C: tetracyclines

How does ciprofloxacin act as an antibiotic? X A: binds a human topoisomerase and prevents it from being used by bacteria X B: binds some types of double strand breaks in bacterial DNA and prevents their repair X C: binds some types of double strand breaks in human DNA and prevents their repair X D: binds bacterial RNA and prevents translation X E: binds the bacterial 50S ribosomal subunit and prevents the peptidyltransferase reaction

X B: binds some types of double strand breaks in bacterial DNA and prevents their repair

What is one key strategy for preventing the emergence of antibiotic resistance in pathogenic bacteria? X A: administering antibiotics in minimal amounts (use low concentrations) X B: using antibiotics freely, even when uncertain that an illness is caused by bacteria X C: annual vaccination programs for seasonal illnesses X D: limiting contact with animal sources of infectious diseases X E: giving 2 or more antibiotics at the same time

X E: giving 2 or more antibiotics at the same time

In addition to T cells, which cell type is required for initiation of all T cellmediated immune responses? ``` X A: Effector cells X B: Memory cells X C: Natural killer cells X D: Antigen-presenting cells X E: B lymphocytes ```

X D: Antigen-presenting cells

The principal function of the immune system is: X A: Defense against cancer X B: Repair of injured tissues X C: Defense against microbial infections X D: Prevention of inflammatory diseases X E: Protection against environmental toxins

X C: Defense against microbial infections

The two major functional classes of effector T lymphocytes are: X A: Helper T lymphocytes and cytotoxic T lymphocytes X B: Natural killer cells and cytotoxic T lymphocytes X C: Memory T cells and effector T cells X D: Helper cells and antigen-presenting cells X E: Cytotoxic T lymphocytes and target cells

X A: Helper T lymphocytes and cytotoxic T lymphocytes

A previously healthy 8-year-old boy is infected with an upper respiratory tract virus for the first time. During the first few hours of infection, which one of the following events occurs? X A: The adaptive immune system responds rapidly to the virus and keeps the viral infection under control. X B: The innate immune system responds rapidly to the viral infection and keeps the viral infection under control. X C: Passive immunity mediated by maternal antibodies limits the spread of infection. X D: B and T lymphocytes recognize the virus and stimulate the innate immune response. X E: The virus causes malignant transformation of respiratory mucosal epithelial cells, and the malignant cells are recognized by the adaptive immune system.

X B: The innate immune system responds rapidly to the viral infection and keeps the viral infection under control.

A standard treatment of animal bite victims, when there is a possibility that the animal was infected with the 37 rabies virus, is administration of human immunoglobulin preparations containing antirabies virus antibodies. Which type of immunity would be established by this treatment? ``` X A: Active humoral immunity X B: Passive humoral immunity X C: Active cell-mediated immunity X D: Passive cell-mediated immunity X E: Innate immunity ```

X B: Passive humoral immunity

Antibodies and T lymphocytes are the respective mediators of which two types of immunity? ``` X A: Innate and adaptive X B: Passive and active X C: Specific and nonspecific X D: Humoral and cell-mediated X E: Adult and neonatal ```

X D: Humoral and cell-mediated

At 15 months of age, a child received a measles-mumps-rubella vaccine (MMR). At age 22, she is living with a 39 family that has not been vaccinated and she is exposed to measles. Despite the exposure, she does not become infected. Which of the following properties of the adaptive immune system is best illustrated by this scenario? ``` X A: Specificity X B: Diversity X C: Specialization X D: Memory X E: Nonreactivity to self ```

X D: Memory

Which of the following cell types is required for all humoral immune responses? ``` X A: Natural killer cells X B: Dendritic cells X C: Cytolytic T lymphocytes X D: B lymphocytes X E: Helper T lymphocytes ```

X D: B lymphocytes

Which of the following is a unique property of the adaptive immune system? X A: Highly diverse repertoire of specificities for antigens X B: Self-nonself discrimination X C: Recognition of common microbial structures X D: Protection against viral infections X E: Responses that have the same kinetics and magnitude on repeated exposure to the same microbe

X A: Highly diverse repertoire of specificities for antigens

A 4-year-old girl stepped on a rusty nail in her backyard. Two days later, she is taken to the pediatrician because her heel is painful, red, and swollen and is warm to the touch. All of the following are mechanisms of innate immunity that may be protecting the patient against pathogenic microbes in the heel wound EXCEPT: X A: Intraepithelial lymphocytes present in the skin X B: Circulating neutrophils migrating to the site of the wound X C: Soluble cytokines that induce a local inflammatory response X D: Circulating anti-tetanus toxin antibodies

X D: Circulating anti-tetanus toxin antibodies

Which of the following comparisons of the innate and adaptive immune systems is FALSE? X A: The innate immune system is more likely to recognize normal self, and therefore cause autoimmunity, than is the adaptive immune system. X B: Receptors used for recognition in innate immunity are encoded in the germline, whereas those of the adaptive immune system are encoded by genes generated via somatic recombination of germline receptor gene loci. X C: The innate and adaptive immune systems share some of the same effector mechanisms. X D: Both the innate and adaptive immune systems can recognize nonmicrobial substances. X E: The innate immune system does not have memory but the adaptive immune system does

X A: The innate immune system is more likely to recognize normal self, and therefore cause autoimmunity, than is the adaptive immune system.

Which of the following is a Toll-like receptor ligand? ``` X A: peptidoglycan X B: transfer RNA (tRNA) X C: IL-2 X D: cytosolic DNA X E: cytosolic RNA ```

X A: peptidoglycan

What is NOT a possible eventual response to activation of signaling through Toll-like receptors (TLRs)? ``` X A: inflammation X B: stimulation of adaptive immunity X C: antiviral state X D: tolerance to TLR ligand X E: macrophage activation ```

X D: tolerance to TLR ligand