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MICROBIO #3

Pataasin ang iyong marka sa homework at exams ngayon gamit ang Quizwiz!

When mitochondria pass electrons donated by NADH through the electron transport chain to molecular oxygen, a theoretical maximum of _________molecules of ATP can be made per oxygen molecule reduced.

In attenuation regulation of the trp operon, which stem loop forms when tryptophan is readily available to the cell? 3:4 1:3 2:3 2:4

3:4

T/F Ampicillin, like penicillin, must be administered by injection because it is rapidly degraded in the stomach and cannot, therefore, be given orally.

T/F Enzymes decrease the overall free energy change in a chemical reaction.

T/F Enzymes increase the rate of a reaction by increasing molecular motion, thereby providing kinetic energy to drive the reaction.

T/F In the process of fermentation an organic substrate, such as glucose, is reduced and an intermediate of the pathway, such as pyruvate, is oxidized.

T/F Metabolic pathways can be either catabolic or anabolic but not both.

T/F Most antiviral agents target extracellular viruses.

T/F Nitrification of ammonia occurs when ammonia is first converted to nitrite and then is converted to nitrate by the nitrogen-fixing bacteria.

T/F Ribozymes are responsible for catalyzing peptide bond formation during protein synthesis and are located in the mitochondria.

T/F Some aerobic bacteria lack the Entner-Doudoroff and Embden-Meyerhoff pathways and instead use the pentose phosphate pathway for glycolysis.

T/F The Michaelis constant (Km) of an enzyme is the substrate concentration that produces maximum velocity.

T/F The catabolism of glucose through a glycolytic pathway, followed by the TCA cycle and culminating in ATP production via the formation of a proton motive force in the electron transport chain, represents the overall reduction of glucose.

T/F The formation of ATP as a result of the activity of the electron transport system is termed substrate-level phosphorylation.

T/F The most commonly used practical form of energy used in cells is adenosine diphosphate.

T/F When comparing two drugs in a disk diffusion assay for drug susceptibility, the drug that produces the larger zone of inhibition is always more effective than the one that produces the smaller zone.

T/F When the amount of enzyme present is held constant, the rate of a reaction will continue to increase as long as the substrate concentration increases.

A neuraminidase inhibitor called _________blank is sometimes used in the treatment of people infected with influenza viruses.

Tamiflu

The electrons that are transferred through the electron transport system were initially transferred from _________. NADH FADH2 ATP NADH and FADH2 oxygen

NADH and FADH2

When does a cell regulate gene expression? a) Pretranscription through posttranslation b) Posttranscription through posttranslation c) Pretranscription through pretranslation d) Posttranscription through pretranslation

Pretranscription through posttranslation

What term describes a set of genes that is controlled by a common regulatory protein? Codon Regulon Transcription Kinase

Regulon

T/F Isoenzymes are different enzymes that catalyze the same reaction but can be regulated independently of one another.

T/F One way in which organisms may exhibit resistance to a drug is the ability to pump the drug out of the cell immediately after it has entered.

T/F Oxidative decarboxylation takes place when pyruvate from the glycolytic pathway is oxidized, producing acetyl-CoA along with one CO2 and one NADH.

T/F Reduction of nitrate to nitrite by Paracoccus denitrificans is an example of anaerobic respiration.

T/F The effects of most antimicrobial drugs are greater if the microorganisms are actively growing.

T/F The electron transport systems in eukaryotes and prokaryotes use different electron carriers.

T/F The equilibrium constant for a redox reaction is called the standard reduction potential.

T/F Treatment of fungal infections is more difficult than treatment of bacterial infections because the greater metabolic similarity between the fungi and their hosts limits the ability of a drug to have a selective toxicity.

T/F Very few Gram-positive bacteria utilize the Entner-Doudoroff glycolytic pathway.

T/F When oxygen accepts electrons, water is produced as a byproduct.

Which of the following is not present in DNA? a) Alpha carbon b) 5'-carbon c) Minor groove d) 3'-hydroxyl e) Double helix

a) Alpha carbon

Which of the following is an example of gene regulation at the posttranslational level? a) Alteration of protein structure b) Early termination of an mRNA transcript c) Initiation of protein synthesis d) Prevention of RNA synthesis

a) Alteration of protein structure

_________ is used to control transcription of some anabolic pathways involved in amino acid biosynthesis. a) Attenuation b) Catabolite repression c) Induction d) All of the choices are correct.

a) Attenuation

Which of the following is NOT true about Kirby-Bauer disk diffusion method? a) Bacteria used to swab a test plate should be at least a week old. b) The diameters of the zones of inhibition are measured to the nearest millimeter. c) The designation of resistance or sensitivity to a drug is determined by comparing the size of the zone of inhibition to a standard table. d) As the minimum inhibitory concentration value increases, the sensitivity of the organism to the drug decreases.

a) Bacteria used to swab a test plate should be at least a week old.

Which of the following is a correct comparison between RNA polymerase holoenzyme that functions in transcription and the primase enzyme that functions in DNA replication? a) Both enzymes synthesize RNA. b) Both enzymes are bound by sigma factor. c) Both enzymes synthesize DNA. d) Both enzymes are composed of RNA.

a) Both enzymes synthesize RNA.

Why are there far fewer antiprotozoal agents than there are antibacterial agents? a) Both protozoa and humans are eukaryotes. b) Protozoa become drug resistant much faster than bacteria. c) Protozoal infections are exceedingly rare worldwide. d) Protozoa are multicellular, while bacteria are unicellular.

a) Both protozoa and humans are eukaryotes.

Which of the following is common to both factor-dependent and factor-independent transcription termination? a) Both types of termination occur following a pause by the polymerase. b) Both types of termination are associated with rho termination factor. c) Both types of termination involve NusA protein. d) None of the choices are correct.

a) Both types of termination occur following a pause by the polymerase.

How were experiments done by Griffith similar to those done by Avery, MacLeod, and McCarty? a) Both used pneumococcal bacteria b) Both used purified DNA c) Both used a mouse host d) Both were done in the 1940s e) Both used enzymes that destroyed DNA

a) Both used pneumococcal bacteria

Which of the following statements best explains why microbial geneticists initially focused on regulation of gene expression at the transcriptional, rather than the translational, level? a) By regulating the first step of protein synthesis, cells conserve the greatest amount of energy. b) The process of transcription was best understood by researchers at the time. c) Cellular regulation of transcription is common to all prokaryotic cells. d) The process of synthesizing an mRNA transcript is much less complex than translation of mRNA into protein.

a) By regulating the first step of protein synthesis, cells conserve the greatest amount of energy.

Cells carry out three major types of work; which of the following involves the synthesis of macromolecules as well as the breakdown of substances for their energy? a) Chemical work b) Transport work c) Mechanical work d) None of the choices are correct.

a) Chemical work

Which enzyme is a topoisomerase? a) DNA gyrase b) DNA ligase c) DNA polymerase I d) DNA polymerase III

a) DNA gyrase

A scientist wishes to develop an antimicrobial agent that specifically targets replication elongation in Escherichia coli without interfering with proteins that catalyze other replication processes. Which of the following experimental designs is most appropriate for the scientist to explore? a) Develop a molecule that interferes with the DNA-binding ability of DNA polymerase III core enzyme b) Modify an existing antibiotic to act as a competitive inhibitor of DNA polymerase I c) Design a drug that modifies the structural configuration of DNA at the oriC locus d) Create a novel protein that acts as a competitive inhibitor of the DNA ligase binding site

a) Develop a molecule that interferes with the DNA-binding ability of DNA polymerase III core enzyme

Who is generally credited with the discovery of sulfanilamide as a chemotherapeutic agent? a) Gerhard Domagk b) Ernest Duchesne c) Ernst Chain d) Robert Koch

a) Gerhard Domagk

Who first demonstrated transformation using mice and two strains of Streptococcus pneumoniae? a) Griffith b) Hershey and Chase c) Avery, McCarty, and MacLeod d) Watson and Crick e) Jacob and Monod

a) Griffith

Griffith's experiment demonstrated transformation because a mouse injected with live R and heat-killed S strains of Streptococcus pneumoniae resulted in death of the mouse and the isolation of live R as well as live S cells. Hypothesize as to the type of cells that Griffith would have observed if transformation had NOT occurred. a) Griffith would have isolated only live R cells from the mouse host. b) Griffith would have isolated both live R and heat-killed S cells from the mouse host. c) Griffith would have isolated only live S cells from the mouse host. d) Griffith would have isolated no cells from the mouse host.

a) Griffith would have isolated only live R cells from the mouse host.

Why does treatment to combat HIV/AIDS typically involve drug combinations? a) HIV frequently develops drug resistance. b) Multiple drugs are needed to eliminate the proviral HIV DNA in the host cells. c) It lowers the overall cost of treatment. d) Different drugs are needed by men and women.

a) HIV frequently develops drug resistance.

If you wished to design an antimicrobial agent that prevented the formation of the 70S initiation complex in bacterial translation, which molecule should specifically be targeted? a) IF-3 b) mRNA c) Peptidyl transferase d) EF-1

a) IF-3

Following the formation of acetyl-CoA, the initial reaction of the Krebs cycle involves the addition of a __________. a) 3-carbon molecule to a 4-carbon molecule b) 2-carbon molecule to a 4-carbon molecule c) 2-carbon molecule to a 6-carbon molecule

b) 2-carbon molecule to a 4-carbon molecule

The activity of an allosteric enzyme is altered by a small molecule known as an _________ _________.

allosteric effector

For one turn of the Krebs cycle, how many NADH are produced? a) Six b) Three c) Depends if the process is aerobic or anaerobic d) Two

b) Three

What enzyme or protein prevents supercoiling of the DNA strands ahead of the replication bubble? a) DnaA b) Topoisomerase c) DNA binding proteins d) Helicase

b) Topoisomerase

When a chemotherapeutic agent is effective against many different pathogens including both Gram-positive and Gram-negative bacteria, it is said to be a _________ antibiotic.

broad-spectrum

The net gain of ATP per molecule of glucose metabolized to pyruvate using Entner-Doudoroff pathway is _________. a) 4 b) 2 c) 1 d) 0

c) 1

Levofloxacin is a bactericidal broad-spectrum drug that is effective against Pseudomonas aeruginosa. The MIC for this organism/drug combination is 1 μg/ml. To kill this pathogen, which level of drug should be administered? a) A concentration well below the MIC b) A concentration 20-25 times the MIC c) A concentration 2-4 times the MIC d) A concentration equal to the MIC

c) A concentration 2-4 times the MIC

DNA polymerases require which of the following elements to replicate DNA? a) A source of energy, a template, an RNA polymerase b) A ribosome, a template, an RNA polymerase c) A template, a primer, a source of energy d) A source of energy, an RNA strand, a ribosome

c) A template, a primer, a source of energy

Penicillin remains one of the most effective drugs against bacteria. This is due to ________. a) the fact that it targets peptidoglycan, a structure not present in host cells b) the secondary destruction mechanism in that it stimulates production of bacterial autolysins c) All of the choices are correct. d) the fact that transpeptidase enzymes bind preferentially to penicillin rather than their substrate e) the ease in which it can be chemically modified to avoid bacterial resistance

c) All of the choices are correct.

Choose the statement that correctly explains how an antibiotic that inhibits protein synthesis can be selective. a) Eukaryotic cells are impermeable to these antibiotics so the antibiotics can't enter them. b) Eukaryotic cells inactivate these antibiotics. c) Antibiotics bind to the 70S bacterial ribosomes but not to the 80S eukaryotic ribosomes.

c) Antibiotics bind to the 70S bacterial ribosomes but not to the 80S eukaryotic ribosomes.

Which of the following is not a regulatory mechanism used to control the lac operon in Escherichia coli? a) Induction b) Catabolite repression c) Attenuation d) All of the choices are correct.

c) Attenuation

Which was common to experiments done by Avery and colleagues as well as Hershey and Chase? a) Radioactive DNA b) Virulent bacteriophage c) Bacterial cells d) Radioactive protein e) Escherichia coli

c) Bacterial cells

From the following statements about biochemical pathways, pick the most descriptive true statement. a) Biochemical pathways can only function for a few runs. b) Biochemical pathways are very well organized and structured and they convert an initial substrate, via a series of steps, into an end product but they can only function for a few runs. c) Biochemical pathways are very well organized and structured and they convert an initial substrate, via a series of steps, into an end product. d) Biochemical pathways are very well organized and structured.

c) Biochemical pathways are very well organized and structured and they convert an initial substrate, via a series of steps, into an end product.

During cellular respiration, cells obtain energy from food molecules such as glucose by using which of the following reactions? a) Cells obtain energy from glucose by using anabolic reactions. b) Cells obtain energy from glucose by using photosynthetic reactions. c) Cells obtain energy from glucose by using oxidation-reduction reactions. d) Cells obtain energy from glucose by using phosphorylating reactions.

c) Cells obtain energy from glucose by using oxidation-reduction reactions.

What enzyme synthesizes the daughter strands during DNA replication? a) Helicase b) RNA polymerase c) DNA polymerase d) DNA primase

c) DNA polymerase

Which of the following is likely to have the most toxic side effects to humans? a) Inhibitors of cell wall synthesis b) Inhibitors of protein synthesis c) Disrupters of cell membrane structure d) Inhibitors of DNA synthesis

c) Disrupters of cell membrane structure

Aminoglycoside antibiotics _________ a) inhibit cell wall synthesis b) inhibit folic acid biosynthesis c) bind to the 30S ribosomal subunit d) bind to bacterial DNA polymerase

c) bind to the 30S ribosomal subunit

An active repressor protein _________. a) binds to an inducer to activate it b) binds to the DNA molecule and promotes transcription initiation c) binds to the DNA molecule and prevents transcription d) is a structural protein e) binds to the RNA polymerase, preventing messenger RNA synthesis

c) binds to the DNA molecule and prevents transcription

The electrons that are transferred through the electron transport system initially belonged to _________. a) NADH b) FADH2 c) both NADH and FADH2 d) oxygen

c) both NADH and FADH2

Cells carry out three major types of work; which of the following involves nutrient uptake and waste elimination? a) Chemical work b) Transport work c) Mechanical work d) None of the choices are correct.

b) Transport work

In the TCA cycle, two carbons are removed from citric acid in the form of __________, thereby regenerating oxaloacetate to complete the cycle. a) acetyl-CoA b) ethanol c) carbon dioxide d) methanol

c) carbon dioxide

The transcribed and translated region of a gene is the __________ region. a) leader b) promoter c) coding d) trailer

c) coding

During breakdown of fatty acids, carbons are removed __________ at a time with each turn of the cycle, and two carbon units are released as __________. a) one; carbon dioxide b) one; methane c) two; acetyl-CoA d) two; ethanol

c) two; acetyl-CoA

Disruption of an enzyme's structure with loss of activity caused by extremes of pH, temperature, or other factors is called _________

denaturation

In some circumstances, when two different carbon sources are available, growth will occur first using one carbon source, then after a short lag period, growth will resume using the second carbon source. This process is called __________ growth. alternating bimorphic diauxic dimorphic

diauxic

A/an _________blank is a drug that blocks the function of a metabolic pathway.

antimetabolitee

Disaccharides and polysaccharides can be processed as nutrients after first being cleaved to monosaccharides by either _________or _________.

hydrolysis, phosphorolysis

Large external polysaccharides are degraded by bacteria and archaea using _________ _________, which they secrete outside the cell.

hydrolytic enzymes

Allosteric enzymes have two separate binding sites: the catalytic site, which binds substrate, and the _________ site, which binds the allosteric effector.

regulatory

Peptide bond formation during protein synthesis is catalyzed by RNA molecules called _________.

ribozymes

RNA molecules that have catalytic activity are known as _________

ribozymes

Until the discovery of _________, enzymes were the only recognized biological molecules that were catalytic.

ribozymes

Exposure to specific antibiotics is a ________ force that helps maintain the resistance gene in a population of bacteria.

selective

An antimicrobial drug that inhibits the growth of bacteria without affecting the growth or function of cells in the human host is described as having _________

selective toxicity

Mycoplasmas do not have a cell wall containing peptidoglycan, thus they are resistant to penicillin since the drug interferes with peptidoglycan synthesis. This is an example of _________ resistance.

inherent

The electron transport chain in bacterial and archaeal cells is located in the plasma membrane, whereas eukaryotic electron transport chains take place in the _________ _________ membrane.

inner mitochondrial

Enzyme activity is changed not only by substrate concentration but also by alterations in pH and _________.

temperature

When cells of a facultative anaerobe such as Paracoccus denitrificans are growing under anaerobic conditions and using nitrate as the terminal electron acceptor, _________blank nitrate reduction is occurring.

dissimilatory

Regulatory enzymes can be switched on and off by reversible covalent modification, usually through the addition and removal of a particular chemical group such as a(n) _________ group.

phosphoryl

When bound to the DNA, the repressor protein usually prevents attachment of the RNA polymerase to the __________. operon operator promoter regulator

promoter

A _________hydrolyzes a protein into its constituent amino acid monomers and a _________enzyme removes amino groups from the amino acids.

protease, deaminase

In a branching metabolic pathway, when an end product is in excess, the end product inhibits the _________ enzyme on the branch leading to its formation.

first

The amount of energy in a system (or cell) available to do useful work at constant temperature and pressure is ΔG or the change in _________ _________.

free energy

A complete enzyme, which consists of protein called the apoenzyme and a nonprotein part called a cofactor, is called a _________.

holoenzyme

Organisms that directly reduce almost all of their pyruvate to lactate are called _________ fermenters.

homolactic

__________ reactions build new organic molecules from smaller inorganic and organic compounds.

Anabolic

T/F Agents that are static and, therefore, do not kill infecting microorganisms are not useful as chemotherapeutic agents.

Arrange the following electron acceptors in the proper order in which they participate in the electron transport chain. 1 = Cytochrome c 2 = Oxygen 3 = Cytochrome c oxidase

1, 3, 2

For each glucose molecule that enters glycolysis, how many times does the Krebs cycle turn? Two One Six Three

How many net ATP molecules are produced for each glucose molecule that enters glycolysis? Three One Two Six

During transcription elongation, how many pyrophosphate molecules are produced from the incorporation of 20 ribonucleoside monophosphates? a) 20 b) 40 c) 60 d) 5

Translation is terminated when a stop codon is presented at the ________ site.

Select the response that describes a broad-spectrum drug.

A drug that is effective against E. coli (Gram-negative) and Staphylococcus aureus (Gram-positive)

In order for the cell to be able to input energy into necessary endergonic reactions, energy-generating processes such as photosynthesis, fermentation, and respiration are used to produce _________

ATP

The energy made available during cell respiration and fermentation is used to make _________, which is then available to provide energy for cellular work.

ATP

The most commonly used form of cellular energy is the nucleoside triphosphate _________.

ATP

_______ is a process that can completely catabolize an organic energy source to CO2 using the glycolytic pathways and TCA cycle with O2 as the terminal electron acceptor for an electron transport chain.

Aerobic respiration

__________ pathways are those that function both catabolically and anabolically.

Amphibolic

T/F Allosteric regulation involves the action of an effector molecule that binds to the active site of an enzyme. By contrast, covalent modification involves the binding of a chemical group to the regulatory site of an enzyme, which changes the conformation of the active site.

T/F An organism can fit into only one nutritional pattern, such as photoheterotrophy, and cannot change if the environmental conditions change.

T/F Many chemolithotrophs are able to produce more ATP from oxidation of their inorganic energy source than chemoheterotrophs produce from the aerobic oxidation of glucose.

T/F Most antiprotozoal drugs have few side effects since there are numerous cellular targets found in protozoa but not found in host cells that can be targeted with antiprotozoal drugs.

T/F One strategy to overcome antibiotic resistance is to use the same antibiotics in animal husbandry as those that are prescribed for humans, since the potential for resistant bacteria to evolve would be limited to only a small number of drug classes.

T/F Since exposure to antibiotics is a selective force for maintaining resistance genes in a population, increasing antibiotic use will reduce overall resistance.

T/F The energy released from catabolic reactions is used to hydrolyze ATP into ADP and orthophosphate within the cell.

T/F The pentose phosphate pathway is the major glycolytic pathway used by archaea.

T/F The regulatory site in an allosteric enzyme is found within the catalytic site.

T/F A stop codon codes for an amino acid as well as the signal to stop.

The _________ _________ is the substrate concentration needed for an enzyme to achieve half maximal velocity.

Michaelis constant

__________ is a two-step process that depends on the activity of at least two genera to carry out the oxidation of ammonia to nitrate.

Nitrification

After the ribosome moves to the next codon on the mRNA, the growing peptide chain is found in which position(s)?

T/ F Many antiprotozoal drugs have toxic side effects since it is challenging to find cellular targets found in protozoa but not found in host cells.

T/F Covalent modification of enzymes most commonly uses phosphoryl, methyl, and adenyl groups.

T/F Glycolysis and the TCA cycle are two of the most important catabolic pathways in chemoorganotrophs.

T/F In order for successful antibiotic therapy, the in vivo level of the antibiotic must be greater than or equal to the MIC.

T/F It is feasible that a regulatory enzyme can be both allosteric and covalently modified. Having both levels of regulation allows for the allosteric effectors to exert varying effects depending on the nature and number of the covalently bound chemical groups.

T/F Most chemolithotrophs have electron transport chains that terminate with O2 as the final electron acceptor.

T/F Penicillin G is frequently injected but not normally given orally because it is rapidly degraded in the stomach.

T/F Pyruvate is converted to carbon dioxide via three separate decarboxylation reactions during the TCA cycle.

T/F The Krebs cycle occurs in the mitochondrion of eukaryotes and the cytoplasm of bacteria and archaea.

T/F The discovery of ribozymes was vital to our understanding of the origins of life since it provided an explanation for the evolution of coding and catalytic molecules.

T/F The energy captured in the phosphorylation of ADP to ATP comes from the proton motive force created when energy is released following the oxidation of electron carriers.

T/F Until the discovery of small molecules that disrupt the viral life cycle, antiviral molecules targeted at a pathogenic virus were thought to kill the host cell in the process, limiting the development of antiviral agents.

T/F A drug that disrupts a microbial function not found in animal cells usually has a higher therapeutic index.

T/F An organism can take advantage of energy available from both light and from organic molecules and exhibit both phototrophy and chemoorganotrophy.

T/F An organism may use glycolysis and the pentose phosphate pathway simultaneously.

T/F Bacteria in biofilms or abscesses may be replicating very slowly and are therefore resistant to chemotherapy because many agents affect pathogens only if they are actively growing and dividing.

T/F Bacterial electron transport chains may be comprised of fewer components and have lower phosphate to oxygen (P/O) ratios than mitochondrial transport chains.

T/F Developing antiprotozoal drugs is a challenge for medicinal chemists due to the fact that novel protozoan targets are limited since both pathogen and host are eukaryotes.

T/F Each enzyme normally has specific pH and temperature optima at which they function best.

T/F Enzyme activity can be greatly affected by the pH and the temperature of the environment in which the enzyme must function.

T/F Enzymes increase the rate of a reaction but do not alter equilibrium constants.

T/F Genes for antibiotic resistance can be found in antibiotic-producing bacteria as well as in non-antibiotic-producing bacteria.

How many different termination codons are used in translation? One Two Three Four

Three

________ molecules deliver amino acids to ribosomes during translation. Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA) Heterogeneous nuclear RNA (hnRNA)

Transfer RNA (tRNA)

DNA replication in bacteria begins at _________.

a single origin and proceeds in both directions

A single "turn" of the Krebs cycle (not including the prior formation of acetyl-CoA from pyruvate) will yield _________. a) 1 ATP, 3 NADH, and 1 FADH2 b) 2 ATP, 3 NADH, and 2 FADH2 c) 1 ATP, 2 NADH, and 2 FADH2 d) 2 ATP, 2 NADH, and 2 FADH2

a) 1 ATP, 3 NADH, and 1 FADH2

Bacterial DNA replication occurs at a rate of _________. a) 1,000 base pairs per second b) 1,000 base pairs per minute c) 100 base pairs per second d) 100 base pairs per minute

a) 1,000 base pairs per second

The net gain of ATP per molecule of glucose metabolized anaerobically via the Embden-Meyerhof pathway in prokaryotes is _________. a) 2 b) 36 c) 38 d) 85

a) 2

If 20% of nucleotides in the DNA of a particular organism contain thymine, estimate the percentage of cytosine that is present in the DNA. a) 30% b) 20% c) 15% d) 80% e) 40%

a) 30%

The aminoglycosides and tetracyclines specifically target the _________blank interfering with _________blank. a) 30S ribosomal subunit; protein synthesis b) cell membrane enzymes; transpeptidation step of peptidoglycan synthesis c) topoisomerases; DNA replication d) tRNAs; protein synthesis

a) 30S ribosomal subunit; protein synthesis

The standard or housekeeping sigma factor used most often by E. coli RNA polymerase under normal growth conditions is called sigma _________. a) 70 b) 32 c) S d) E

a) 70

A certain polypeptide is 100 amino acids in length. During translation of this polypeptide, how many amino acids entered through the A site of the ribosome? a) 99 b) 100 c) 9 d) 1 e) 50

a) 99

What might be a reason for the accumulation of improperly folded protein complexes in the bacterial cell cytoplasm following translation? a) A problem exists with the functioning of molecular chaperones b) The cell is synthesizing proteins too rapidly c) Polysomes are forming on the mRNA d) The proteins are being transcribed but not translated

a) A problem exists with the functioning of molecular chaperones

Which statement best describes the mechanism(s) of posttranslational regulation of gene expression? a) Allosteric regulation following transcription of mRNA occurs in many biosynthetic pathways. b) Protein synthesis is often repressed by feedback or noncompetitive inhibition. c) Covalent modification of newly synthesized proteins generally has no marked effect on protein function. d) Once a protein is synthesized, there is little to no postranslational modification.

a) Allosteric regulation following transcription of mRNA occurs in many biosynthetic pathways.

An sRNA is isolated from a bacterial cell. What would you do to determine whether it is a cis-encoded or a trans-encoded sequence? a) Identify whether or not the sRNA sequence is complementary to the coding strand of mRNA gene target. b) Analyze the molecular position of hydrogen atoms in the sRNA nucleotides. c) Determine whether the sRNA binds to mRNA or to tRNA. d) Find out if the sRNA acts as a transcriptional or as a translational inhibitor.

a) Identify whether or not the sRNA sequence is complementary to the coding strand of mRNA gene target.

__________ alter repressor proteins thereby increasing the rate of transcription initiation. a) Inducers b) Corepressors c) Effectors d) Modulators

a) Inducers

What is the function of cyclic dimeric GMP in bacterial global regulation systems? a) It acts as a secondary nucleotide messenger b)It is a sensor kinase c) It converts GTP to cGTP d) It is an autoinducer

a) It acts as a secondary nucleotide messenger

Choose the method of antimicrobial susceptibility testing that involves measuring and evaluating diameters of zones of inhibition around antibiotic disks placed on a culture of bacteria prior to incubation. a) Kirby-Bauer test b) Dilution susceptibility test c) Gram stain test d) Etest®

a) Kirby-Bauer test

In which situation might methylation of membrane proteins in Escherichia coli initiate a phosphorelay system that evokes clockwise rotation of flagella? a) Presence of a chemorepellent in the extracellular environment b) Change in environmental osmotic pressure c) Utilization of lactose due during diauxic growth d) Cellular population reaches a quorum

a) Presence of a chemorepellent in the extracellular environment

Which statement defends the concept that the term "gene" is better defined as a nucleotide sequence that encodes for one or more functional products rather than encoding for one or more functional proteins? a) Products of genes include ribonucleotides as well as proteins. b) Intron sequences in DNA do not encode proteins. c) The genetic code is redundant, therefore the same codon may be encoded by different DNA triplets. d) Genes in bacteria are organized as operons that can lead to several protein products

a) Products of genes include ribonucleotides as well as proteins.

In terms of relatedness to a specific cellular process, which protein does not belong with the others? a) RNA polymerase holoenzyme b) DNA polymerase holoenzyme c) Ribonuclease d) DNA ligase

a) RNA polymerase holoenzyme

How could the Hershey and Chase experimental procedure be redesigned to support a hypothesis that RNA carries genetic information? a) Replace T2 bacteriophage with an RNA virus b) Replace Escherichia with an RNA virus c) Use 35S and 32P to label the same components of an RNA virus and T2 bacteriophage, then add both viruses to Escherichia cells d) Use 35S to label an RNA virus and 32P to label a DNA virus

a) Replace T2 bacteriophage with an RNA virus

In the Hershey and Chase experiment, how did labeling DNA and protein with different radioactive isotopes demonstrate that DNA, rather than protein, carried the genetic information in the T2 virus? a) Researchers could track which part of the virus entered a bacterial cell. b) Researchers could use radio labeling to inactivate DNA and protein in the bacteria. c) Researchers could distinguish bacterial DNA from viral protein. d) Researchers could better elucidate DNA or protein structure. e) Researchers could monitor how DNA interacted with protein in the virus.

a) Researchers could track which part of the virus entered a bacterial cell.

Rationalize why HIV-positive patients are given a "cocktail" of drugs rather than a single antiviral agent to target the virus? a) Reverse transcriptase, used by HIV for nucleic acid synthesis, cannot proofread for errors so mutations leading to multiple drug resistance are common. b) Using several drugs together enhances the efficacy of each one. c) It is more cost-effective to give a combination of drugs simultaneously, rather than a single drug consecutively. d) Each drug targets a different mechanism in the virus, collectively ridding the virus from the host.

a) Reverse transcriptase, used by HIV for nucleic acid synthesis, cannot proofread for errors so mutations leading to multiple drug resistance are common.

Ribozymes are important molecules that were discovered in the 1980s. Select the most complete true statement below concerning ribozymes. a) Ribozymes are RNA molecules that catalyze reactions and have Michaelis-Menten Kinetics. b) Ribozymes have Michaelis-Menten Kinetics. c) Ribozymes are proteins that catalyze reactions. d) Ribozymes are RNA molecules that catalyze reactions.

a) Ribozymes are RNA molecules that catalyze reactions and have Michaelis-Menten Kinetics.

Serratia marcescens bacteria has a gene that regulates red pigment production by cells. A student inoculates two nutrient agar plates of Serratia and incubates one at 25C and the other at 37C. Following incubation, the student observes that colonies on the 25oC plate are red while those on the 37oC plate are nonpigmented. Which of the following statements is a logical conclusion based on these results? a) Serratia genes for pigment production are induced at certain temperatures. b) Serratia cells undergo a genotypic change that is proportional to changes in temperature. c) Low temperatures cause repression of certain housekeeping genes. d) This is an example of constitutive gene expression.

a) Serratia genes for pigment production are induced at certain temperatures.

What would be the most likely outcome if the genetic code was not degenerate? a) The effect of some mutations would increase. b) The effect of some mutations would decrease. c) The mutation rate would remain the same. d) The number of stop codons would increase.

a) The effect of some mutations would increase.

What event occurs as the ribosome shifts down the mRNA by a distance of three nucleotides? a) The tRNA that was in the P site moves into the E site. b) The tRNA that was in the E site moves into the A site. c) The tRNA that was in the A site moves into the E site. d) The tRNA that was in the P site moves into the A site.

a) The tRNA that was in the P site moves into the E site.

While examining the sequence of nucleotides in the replicon region of bacterial DNA, you note an abundance of adenine and thymine base pairs. This leads you to conclude that this particular section of the DNA must be the _________. a) oriC site b) Pribnow box c) Shine-Dalgarno sequence d) ter site

a) oriC site

In terms of global gene regulation, which of the following molecules is most similar to c-di-GMP and cAMP? a) ppGpp b) rRNA c) ATP d) EnvZ

a) ppGpp

Which of the following was the major contribution made by Avery, MacLeod, and McCarty that strengthened the argument that the transforming agent in Griffith's experiment was DNA? a) Transformation of nonvirulent cells with a DNA extract was blocked only if DNase was added. b) Transformation of nonvirulent cells with a DNA extract was successful when DNase was added. c) Transformation of nonvirulent cells with a DNA extract was blocked only if RNase was added. d) Transformation of nonvirulent cells with a DNA extract was blocked only if protease was added.

a) Transformation of nonvirulent cells with a DNA extract was blocked only if DNase was added.

Which is true regarding translation in bacteria? a) Translation begins with formation of the 30S initiation complex. b) Translation ends when the Shine-Dalgarno sequence is reached. c) The 70S ribosome is composed of a 20S and 50S subunit. d) All of the choices are correct.

a) Translation begins with formation of the 30S initiation complex.

How do translational riboswitches and transcriptional riboswitches differ? a) Translational riboswitches are mainly observed in Gram-negative bacteria while transcriptional riboswitches are associated with Gram-positive bacteria. b) Translational riboswitches are located in the mRNA trailer while transcriptional riboswitches are in mRNA leader sequence. c) Translational riboswitch effectors bind to ribosomes while transcriptional riboswitch effectors bind to mRNA. d) All of these are differences between translational and transcriptional riboswitches.

a) Translational riboswitches are mainly in Gram-negative bacteria while transcriptional riboswitches are associated with Gram-positive bacteria.

Which nucleotide triphosphate supplies the energy required for the synthesis of the complex bacterial cell wall polymer, peptidoglycan? a) Uridine 5'- triphosphate b) Adenosine triphosphate c)Guanosine 5'- triphosphate

a) Uridine 5'- triphosphate

In bacteria, when protons are pumped across the cell membrane, _________. a) a proton motive force is created b) water is made c) electrons are lost d) NADH gets reduced

a) a proton motive force is created

During feedback inhibition, the inhibitor binds to the __________. a) allosteric site of the enzyme being inhibited b) neither the active site nor the allosteric site of the enzyme being inhibited c) both the active site and the allosteric site of the enzyme being inhibited

a) allosteric site of the enzyme being inhibited

If an enzyme consists of a protein component and a nonprotein component, the protein component is referred as the _________. a) apoenzyme b) coenzyme c) holoenzyme d) prosthetic group

a) apoenzyme

In __________, ribosomes can attach to the mRNA and begin translation even though transcription has not been completed. a) bacteria b) eukaryotes c) fungi d) protozoa and some plants

a) bacteria

Most antiprotozoal drugs target _________. a) biosynthetic pathways b) genome integration c) capsid production and maturation d) ribosomes

a) biosynthetic pathways

In most cases, fueling reactions are __________ reactions. a) catabolic b) anabolic c) reducing

a) catabolic

The treatment for pneumonia caused by Pneumocystis jiroveci in AIDS patients is _________ a) combination of trimethoprim and sulfamethoxasole b) amantadine c) streptomycin d) miconazole

a) combination of trimethoprim and sulfamethoxasole

If flagellar rotation of Escherichia coli cells is , then CheA is . a) counterclockwise; unphosphorylated b) counterclockwise; autophosphorylated c) clockwise; autophosphorylated d) clockwise; unphosphorylated

a) counterclockwise; unphosphorylated

Foscarnet, a pyrophosphate analog, is used to treat _________ infections. a) cytomegalovirus b) HIV c) human papillomavirus d) influenza A

a) cytomegalovirus

The terms phototroph and chemotroph refer to an organism's source of _________. a) energy b) electrons c) carbon d) nitrogen

a) energy

A bacterial biosynthetic pathway synthesizes an amino acid in a series of steps, each catalyzed by a different enzyme. The bacteria is transferred to fresh media where the amino acid is present in abundance. The amino acid binds to a regulatory site on the first enzyme in the pathway, effectively shutting down the entire process. This is an example of __________. a) feedback inhibition b) metabolic channeling c) covalent modification d) gene regulation

a) feedback inhibition

The chemotherapeutic agent must reach levels in the body that are _________ a) greater than b) equal to c) less than

a) greater than

In an electron transport chain, the first electron carrier __________. a) has the most negative E'o and each successive carrier is slightly less negative b) has an E'o of zero c) has a similar E'o as each successive carrier

a) has the most negative E'o and each successive carrier is slightly less negative

Consider the metabolism of a chlorophyll-based phototroph. In oxidative phosphorylation during cell respiration, the source of energy is _________ whereas in photophosphorylation the source of energy is __________. a) highly reduced organic compounds; light b) NADH; NADPH c) electron transport chain; chlorophyll d) ATP; light

a) highly reduced organic compounds; light

If autophosphorylation of CheA protein does not occur, then Escherichia coli cells must be _________. a) in a gradient of a chemoattractant b) in a gradient of a chemorepellant c) tumbling d) rotating flagella clockwise

a) in a gradient of a chemoattractant

When a repressor binds to the operator site on the DNA it normally _________. a) inhibits the initiation of transcription b) reduces the rate of transcription c) terminates transcription that has already been initiated d) has no effect on transcription

a) inhibits the initiation of transcription

The transcribed, but not translated, sequence that is immediately upstream of the region that encodes the functional product is called the __________ region. a) leader b) promoter c) coding

a) leader

The lowest concentration of an antibiotic that prevents growth is the _________ a) minimal inhibitory concentration (MIC) b) minimal lethal concentration (MLC) c) 50% inhibitory dose d) All of the choices are correct.

a) minimal inhibitory concentration (MIC)

The Embden-Meyerhof, Entner-Doudoroff and pentose phosphate pathways all bring about the reduction of coenzymes (either NAD+ or NADP+). The reduced coenzymes __________. a) provide reducing power to fuel subsequent reactions b) are converted into ATP for energy c) can no longer be oxidized d) serve as precursor molecules for anabolic reactions

a) provide reducing power to fuel subsequent reactions

The TCA cycle __________. a) provides reducing power in the form of NADH and FADH2, and precursor molecules for anabolic reactions b) produces pyruvate as a source of electrons to drive the electron transport chain c) is a divergent pathway that produces ATP and CO2 d) yields 34 molecules of ATP

a) provides reducing power in the form of NADH and FADH2, and precursor molecules for anabolic reactions

Sulfonamides inhibit the production of folic acid and, therefore, inhibit the synthesis of _________ a) purines and pyrimidines b) ribose c) aromatic amino acids d) peptidoglycan

a) purines and pyrimidines

Two amino acids that are found in some proteins due to exceptions in the universal genetic code are _________. a) pyrrolysine and selenocysteine b) lysine and selenocysteine c) pyrrolysine and cysteine d) lysine and cysteine

a) pyrrolysine and selenocysteine

The __________ is the electron donor in a redox reaction. a) reductant b) oxidant c) enzyme d) product

a) reductant

The process of decarboxylation involves ________. a) removing carbon b) removing water c) removing hydrogen d) adding water

a) removing carbon

If the product of a functional gene is not a protein, what other product(s) might be encoded by the gene? a) tRNA and rRNA b) tRNA and mRNA c) mRNA and rRNA d) mRNA, tRNA, and RNA

a) tRNA and rRNA

The terminator versus anti-terminator function of a specific riboswitch used by bacteria to regulate amino acid-related genes is determined by _________. a) the binding of the appropriate uncharged tRNA b) the rate of leader peptide synthesis c) the binding of the T box binding protein d) the utilization of the appropriate sigma factor by RNA polymerase

a) the binding of the appropriate uncharged tRNA

Consider a biochemical pathway with five steps that lead to the production of product Q. If there is an abundance of product Q, the most efficient way to slow down the entire pathway would be to regulate __________. a) the first enzyme in the pathway b) the last enzyme in the pathway c) every enzyme in the pathway

a) the first enzyme in the pathway

The activity of adenyl cyclase is influenced by _________. a) the phosphotransferase system b) the presence of lactose in the environment c) homoserine lactones d) None of the choices are correct.

a) the phosphotransferase system

The drug level required for the clinical treatment of a particular infection is called the _________ a) therapeutic dose b) toxic dose c) therapeutic index d) minimal inhibitory concentration

a) therapeutic dose

Protein translocation differs from protein secretion in that __________. a) translocation refers to movement from the cytoplasm to or across the plasma membrane, whereas secretion refers to movement of the protein to the exterior of the cell b) translocation refers to movement from one side of the cell to the other, whereas secretion refers to movement across the LPS layer c) translocation refers to movement of proteins in Gram-positive bacteria, whereas secretion refers to movement of proteins in Gram-negative bacteria d) translocation refers to movement of the protein to the exterior of the cell, whereas secretion refers to movement from the cytoplasm to or across the plasma membrane

a) translocation refers to movement from the cytoplasm to or across the plasma membrane, whereas secretion refers to movement of the protein to the exterior of the cell

If Escherichia coli is cultured in broth containing both glucose and lactose, it _________. a) uses glucose preferentially until the supply is exhausted, then uses lactose b) uses lactose preferentially until the supply is exhausted, then uses glucose

a) uses glucose preferentially until the supply is exhausted, then uses lactose

Based on phosphate transfer potential, which is more likely to happen? a) Phosphoenolpyruvate will transfer phosphate to ADP b) ATP will transfer phosphate to phosphoenolpyruvate c) There will be no phosphate transfer between these molecules

a)Phosphoenolpyruvate will transfer phosphate to ADP

ATP has a high phosphate transfer potential because it readily donates a phosphoryl group to other molecules. From your understanding of substrate-level phosphorylation, compare ATP's phosphate transfer potential to other molecules by choosing the correct statement below. a) ATP has the same phosphate transfer potential as glucose 6-phosphate and phosphoenolpyruvate (PEP). b) ATP has a higher phosphate transfer potential than glucose 6-phosphate and lower than phosphoenolpyruvate (PEP).

b) ATP has a higher phosphate transfer potential than glucose 6-phosphate and lower than phosphoenolpyruvate (PEP).

What obstacles must be overcome by the cell when transcribing genes that code for tRNA and rRNA? a) The molecules are required in large amounts. b) All of the choices are correct. c) Multiple versions of tRNA must be synthesized. d) Adequate ratios of each molecule must be produced.

b) All of the choices are correct.

Some drug-resistant organisms produce β-lactamases; enzymes that hydrolyze the β-lactam ring. Clavulanate is a chemical compound that works to inactivate β-lactamase enzymes. Which antibiotic would you find co-prescribed with clavulanate as a means of combating drug resistant infections? a) Tetracycline b) Amoxicillin c) Ciprofloxacin d) Erythromycin

b) Amoxicillin

Which of the following is sometimes useful against viral infections? a) Trimethoprim b) Azidothymidine c) Rifampin d) Streptomycin

b) Azidothymidine

Which of the following is not a regulatory mechanism used to control the trp operon in Escherichia coli? a) Repression b) Catabolite repression c) Attenuation d) All of the choices are correct.

b) Catabolite repression

Antifungals have a selective toxicity that targets which aspect of fungal cell biology? a) Intron removal and exon splicing b) Cell membrane synthesis c) Cell wall synthesis d) Protein secretion

b) Cell membrane synthesis

__________ activate repressor proteins, thereby decreasing the synthesis of certain enzymes. a) Inducers b) Corepressors c) Effectors d) Modulators

b) Corepressors

___________ refers to the removal of an amino group from an amino acid. One mechanism for this removal is __________, in which the amino group is transferred to an acceptor molecule. a) Deamination; hydrolysis b) Deamination; transamination c) Transamination; deamination d) Hydrolysis; transamination

b) Deamination; transamination

The use of the arsenic compound Salvarsan as a treatment for syphilis is credited to _________ a) Fleming b) Ehrlich c) Waksman d) Chain

b) Ehrlich

Which of the following inhibits protein synthesis? a) Dapsone b) Erythromycin c) Penicillin d) Isoniazid

b) Erythromycin

Why are there far fewer antifungal agents than there are antibacterial agents? a) There are far fewer fungi than bacteria. b) Fungal cells are much more similar to human cells than are bacterial cells. c) Fungi become drug resistant much faster than bacteria. d) Fungal infections are always superficial.

b) Fungal cells are much more similar to human cells than are bacterial cells.

Which of the following is not true of an effective antibacterial drug? a) It should not be a target of attack by the microbe. b) It should target the plasma membrane since this is the one structure that bacteria and host cells have in common. c) It should specifically target a unique pathogen process or molecule. d) It should have a low minimum inhibitory concentration against a wide range of organisms.

b) It should target the plasma membrane since this is the one structure that bacteria and host cells have in common.

Which of the following is produced in largest numbers by the TCA cycle? a) ATP (GTP) b) NADH c) FADH d) CO2

b) NADH

What statement is TRUE about tRNA? a) Only one tRNA can recognize a stop codon. b) No tRNA can recognize a stop codon. c) Some but not all tRNAs can recognize a stop codon. d) All tRNAs can recognize a stop codon, but they do so rarely. e) All tRNAs can recognize a stop codon, and they do so all the time.

b) No tRNA can recognize a stop codon.

What enzymes hydrolyze proteins, releasing amino acids? a) Tranaminases b) Proteases c) Decarboxylases d) Deaminases

b) Proteases

Which of the following is normally treated by antifungal creams and solutions? a) Systemic mycoses b) Superficial mycoses c) Subcutaneous mycoses d) Intramuscular mycoses

b) Superficial mycoses

A patient arrives at the hospital with a Staphylococcus infection. A microbiologist at the hospital runs a disk diffusion test and obtains a zone diameter of 17 mm for clindamycin. The zone diameter interpretive standards for this drug-microbe combination are listed as: Resistant = <15, Intermediate = 15-20, Susceptible = >20. How should the results of this disk diffusion test be interpreted? a) The Staphylococcus shows some susceptibility to the antibiotic clindamycin. It would be recommended to use this antibiotic for this infection. b) The Staphylococcus shows some susceptibility to the antibiotic clindamycin. It would not be recommended to use this antibiotic for this infection. c) The Staphylococcus can be killed by the use of the antibiotic clindamycin. It would be recommended to use this antibiotic for this infection. d) The Staphylococcus can not be killed by the use of the antibiotic clindamycin. It would not be recommended to use this antibiotic for this infection.

b) The Staphylococcus shows some susceptibility to the antibiotic clindamycin. It would not be recommended to use this antibiotic for this infection.

Which is a false statement regarding riboswitches? a) Riboswitches are regions in the 5' untranslated leader of an mRNA. b) The effector molecules that bind to riboswitches are proteins. c) When the effector binds the riboswitch, it may serve to terminate transcription of its target mRNA. d) When the effector binds the riboswitch, it may serve to continue transcription of its target mRNA.

b) The effector molecules that bind to riboswitches are proteins.

Which is false regarding the two-component regulatory system in bacteria? a) The system involves a sensor kinase and a response regulator. b) The sensor kinase is phosphorylated by the response regulator when the extracellular environment changes. c) Regulation of OmpF and OmpC porin proteins in E. coli is modulated by this type of system. d) One part of the system is exposed to the external cellular environment while another part is exposed to the cytoplasm.

b) The sensor kinase is phosphorylated by the response regulator when the extracellular environment changes.

Which of the following is the major reason why it has been difficult to treat viral infections with chemotherapeutic agents? a) Viral metabolism resembles that of their hosts so there is no selective point of attack. b) Viruses use the metabolic machinery of their hosts, which limits many of the potential points of attack. c) Viruses have no metabolism and therefore offer no selective point of attack. d) Actually, viruses are not difficult to treat with chemotherapeutic agents.

b) Viruses use the metabolic machinery of their hosts, which limits many of the potential points of attack.

The difference between a prosthetic group and a coenzyme is that _________. a) a prosthetic group is loosely attached to the aopenzyme, whereas a coenzyme is tightly bound b) a prosthetic group is firmly attached to the aopenzyme, whereas a coenzyme is loosely bound c) a prosthetic group dissociates from the apoenzyme after the products are made, whereas a coenzyme remains firmly attached d) a prosthetic group is made of protein, whereas a coenzyme is vitamin-derived

b) a prosthetic group is firmly attached to the aopenzyme, whereas a coenzyme is loosely bound

The substrate of an enzyme binds at the _________. a) affinity site b) active site c) determinative site d) reaction site

b) active site

The portion of the tRNA molecule that binds to the codon on the mRNA is called the _________. a) c-codon b) anticodon c) complementary codon d) paracodon

b) anticodon

The class of antimicrobials that would have the most selective toxicity is _________. a) antimicrobials that interfere with cell membrane structure and function b) antimicrobials that inhibit cell wall synthesis c) antimicrobials that inhibit protein synthesis d) antimicrobials that interfere with nucleic acid structure and function

b) antimicrobials that inhibit cell wall synthesis

In an electron tower, the electron donors with the most negative reduction potentials _________. a) are at the bottom b) are at the top and include glucose and NADH c) are at the top and include carbon dioxide

b) are at the top and include glucose and NADH

When the catabolite activator protein binds to its binding site in DNA, it _________. a) displaces repressors b) bends the DNA c) promotes the assembly of other transcription factors at the promoter d) eliminates the need for a sigma factor on the part of RNA polymerase

b) bends the DNA

Fatty acids are metabolized by the __________ pathway. a) alpha-oxidation b) beta-oxidation c) gamma-oxidation

b) beta-oxidation

A nonprotein component of an enzyme that is loosely attached to the protein component is referred to as a(n) _________. a) apoenzyme b) coenzyme c) holoenzyme d) prosthetic group

b) coenzyme

The genetic code is said to be __________ because more than one codon will specify a particular amino acid. a) ambiguous b) degenerate c) multiplicative d) repetitious

b) degenerate

The genetic information in DNA is divided into units called _________. a) proteins b) genes c) genotype d) phenotype

b) genes

Sulfonamides and other drugs that inhibit folic acid synthesis have a high therapeutic index because _________ a) humans do not use folic acid b) humans do not synthesize folic acid but obtain it in their diets c) humans synthesize folic acid by a process that is not sensitive to sulfonamides d) None of the choices are correct.

b) humans do not synthesize folic acid but obtain it in their diets

The binding of a positive allosteric regulator molecule will _________. a) decrease the ability of the substrate to bind to the allosteric site b) increase the ability of the substrate to bind to the catalytic site c) decrease the ability of the substrate to bind to the catalytic site

b) increase the ability of the substrate to bind to the catalytic site

Bacitracin _________ a) inhibits DNA replication b) inhibits peptidoglycan synthesis c) interferes with protein synthesis d) interferes with plasma membrane function

b) inhibits peptidoglycan synthesis

The substances that donate electrons to the electron transport chains of chemolithotrophs are ___________. a) carbohydrates b) inorganic compounds c) lipids d) methane gas and alcohols

b) inorganic compounds

The site on the DNA to which a repressor protein binds is the __________. a) operon b) operator c) promoter d) regulator

b) operator

The __________ is the electron acceptor in a redox reaction. a) reductant b) oxidant c) enzyme d) product

b) oxidant

In two component regulatory systems, the response regulator typically receives a/an __________ from the sensor kinase when it has been activated. a) pyruvate group b) phosphoryl group c) acetyl group d) methyl group

b) phosphoryl group

The region at which the RNA polymerase binds is the __________ region. a) leader b) promoter c) coding d) trailer

b) promoter

While standard two-component regulatory systems typically act to control gene transcription, phosphorelay systems can act either to control gene transcription or to control. a) translation b) protein activity c) DNA replication d) All of the choices are correct.

b) protein activity

When RNA polymerase catalyzes the addition of a nucleotide to a growing mRNA chain, a byproduct of this reaction is _________. a) phosphate b) pyrophosphate c) orthophosphate d) water

b) pyrophosphate

The standard reduction potential of a redox reaction is a measure of the tendency of the __________ to __________ electrons. a) reductant; gain b) reductant; lose c) oxidant; gain d) oxidant; lose

b) reductant; lose

Production of ATP using the energy liberated when electrons from reduced chemical bonds are passed through the electron transport system is generally referred to as _________. a) chemiosmotic b) respiration c) substrate-level d) conformational change

b) respiration

Exceptions to the genetic code exist in cases where __________. a) instead of coding for serine, the UCA codon codes for phenylalanine b) stop codons are used to code for additional amino acids such as selenocysteine and pyrrolysine c) arginine and serine use the same four codons d) the start codon, AUG, codes for selenocysteine

b) stop codons are used to code for additional amino acids such as selenocysteine and pyrrolysine

The sensor kinase for the OmpF: OmpC two-component regulatory system is _________. a) the OmpK protein b) the EnvZ protein c) the MicF RNA d) None of the choices are correct.

b) the EnvZ protein

In a branched pathway with many end products, an abundance of one of the end products will usually inhibit _________. a) the first step in the set of pathways b) the first committed step in the branch of the pathway leading to the production of that particular product c) the last step before the branch leading to the production of that particular end product d) the last step in the production of that particular product

b) the first committed step in the branch of the pathway leading to the production of that particular product

For many years microbial geneticists focused almost exclusively on the regulation of transcription initiation. A likely reason for this is _________. a) it is easier to study proteins than RNA b) the process of transcription in microbes was better understood than that of translation c) it was thought that gene expression in microbes was regulated solely by proteins d) examples of translational control had not been discovered in microbes

b) the process of transcription in microbes was better understood than that of translation

Fluoroquinolones are known to damage tendons and nerves in patients taking the drug. Side effects from quinolones are unavoidable because _________ a) they inhibit protein synthesis in bacterial cells, which simultaneously disrupts protein synthesis in the host, preventing the production of cartilage b) they inhibit DNA synthesis, and bacteria and eukaryotes carry out very similar mechanisms for DNA replication c) they disrupt folic acid synthesis, and both bacteria and humans require folic acid for growth d) their mechanism of action is to disrupt cytoskeletal fibers in bacteria, which correlates to connective tissue in humans

b) they inhibit DNA synthesis, and bacteria and eukaryotes carry out very similar mechanisms for DNA replication

The genetic code is translated in groups of __________ bases. a) two b) three c) four d) five

b) three

The process by which the base sequence of all or a portion of a DNA molecule is used to direct the synthesis of an RNA molecule is called _________. a) replication b) transcription c) reverse transcription d) translation

b) transcription

The __________ reaction sequentially links adjacent amino acids into the growing polypeptide chain. a) dipeptidation b) transpeptidation c) peptidation d) propeptidation

b) transpeptidation

How does E. coli assess whether the level of attractant in the media is increasing or decreasing in order to modulate runs vs. tumbles? a) When CheY is phosphorylated, the cell runs, indicating high levels of attractant in the media. b) When attractant is high, CheA autophosphorylates and the cell runs. c) Every few seconds the attractant level is measured by comparing the level of methylation on the cytoplasmic side of the MCPs against the level of bound attractant on the periplasmic side of the MCPs. d) Every few seconds it measures the level of methylated sites on the periplasmic side of the MCPs against the level of attractant bound to MCPs in the cytoplasm.

c) Every few seconds the attractant level is measured by comparing the level of methylation on the cytoplasmic side of the MCPs against the level of bound attractant on the periplasmic side of the MCPs.

In the conjugate redox pair Fe3+ + e− → Fe2+ _________. a) Fe2+ readily accepts electrons from Fe3+ b) Fe3+ is the reducing agent while Fe2+ is the oxidizing agent c) Fe2+ is the reducing agent while Fe3+ is the oxidizing agent d) Fe3+readily donates electron to Fe2+

c) Fe2+ is the reducing agent while Fe3+ is the oxidizing agent

Most E. coli antisense RNAs work with a protein called __________ to regulate their target mRNAs. a) CAP b) MicF c) Hfq d) None of the choices are correct.

c) Hfq

What statement is correct regarding sigma factor? a) It is involved in the termination of replication b) None of the choices are correct. c) It recognizes the promoter region d) It forms mRNA e) It forms an open complex

c) It recognizes the promoter region

Cells carry out three major types of work. Which of the following involves energy for cell motility and the movement of structures within cells? a) Chemical work b) Transport work c) Mechanical work d) None of the choices are correct.

c) Mechanical work

Which of the following chemical equations best describes the reduction of the coenzyme NAD+? a) NAD+ + H++2e- → NADH2 b) NAD + H → NADH c) NAD+ +2H+ +2e- → NADH + H+ d) NADH → NAD+ + H+

c) NAD+ +2H+ +2e- → NADH + H+

The number of ATP molecules generated per atom of oxygen that is reduced when electrons are passed from NADH or reduced FAD (FADH) to O2 is called the _________. a) utilization ratio b) energy yield c) P/O ratio

c) P/O ratio

Which of the following antibiotics specifically inhibits DNA synthesis? a) Gentamycin b) Polymyxin B c) Quinolones d) Tetracycline

c) Quinolones

Bacterial responses to phage infection can be compared to the human immune system. Which of the phrases is true? a) Restriction-modification can be compared to B cell responses and CRISPR/Cas to T cell responses. b) Restriction-modification can be compared to the complement system and CRISPR/Cas to inflammation. c) Restriction-modification can be compared to innate immunity and CRISPR/Cas to adaptive immunity.

c) Restriction-modification can be compared to innate immunity and CRISPR/Cas to adaptive immunity.

Which of the following is not true regarding the development of antimicrobial drugs? a) In addition to searching for molecules that are naturally-produced, the development of synthetic drugs and use of bacteriophages to kill bacteria is being explored. b) Microbial samples taken from all over the world are being analyzed for potential antimicrobial activity. c) Since the source of naturally-occuring molecules has been exhausted, only synthetic molecules are currently being designed and developed against pathogenic microbes. d) Antimicrobial drugs are being designed using knowledge of the three-dimensional structure of the potential target.

c) Since the source of naturally-occuring molecules has been exhausted, only synthetic molecules are currently being designed and developed against pathogenic microbes.

Guanine tetraphosphate (ppGpp) is associated with which process? a) Spore formation in Bacillus b) Chemiosmosis in Paracoccus c) Stringent response in Escherichia d) Quorum sensing in Vibrio

c) Stringent response in Escherichia

Which of the following is NOT true regarding ATP synthases? a) They require proton motive force to make ATP. b) They span the inner membrane of mitochondria. c) The proton flow is outward during ATP synthesis. d) The subunits of ATP synthase undergo conformational changes during ATP production.

c) The proton flow is outward during ATP synthesis.

The antibacterial drug mechanism of action that would have the highest therapeutic index is _________. a) a drug that inhibits RNA polymerase b) a drug that targets the ribosome to prevent protein synthesis c) a drug that targets peptidoglycan cross-linking d) a drug that inhibits DNA polymerase

c) a drug that targets peptidoglycan cross-linking

In higher eukaryotes, most aerobically generated ATP is produced by _________. a) glycolysis b) the TCA cycle c) a membrane-bound proton translocating ATP synthase during oxidative phosphorylation d) All of the choices are correct.

c) a membrane-bound proton translocating ATP synthase during oxidative phosphorylation

The pyruvate dehydrogenase complex oxidizes and cleaves pyruvate to form one CO2 and _________. a) lactate b) isocitric acid c) acetyl-CoA d) succinyl-CoA

c) acetyl-CoA

Glutamine synthetase is an enzyme involved in nitrogen assimilation in E. coli. Regulation is mediated by the addition of a(n) _________ group to each of the 12 enzyme subunits. a) phosphoryl b) hydroxyl c) adenylyl d) methyl

c) adenylyl

Chemotherapeutic agents that are natural products of microorganisms are most specifically referred to as _________ a) antimicrobial agents b) synthetic drugs c) antibiotics d) semisynthetic drugs

c) antibiotics

The __________ is a factor-independent termination site found in the leader region of certain operons, which, under the influence of ribosome behavior, controls the continued transcription of that operon. a) modulator b) operator c) attenuator d) terminator

c) attenuator

Bioluminescence in Vibrio fischeri is dependent on __________. a) phosphorylation of CheY protein b) posttranslational regulation of Spo0A protein c) autoregulation of the luxI gene d) destabilization of luxM mRNA

c) autoregulation of the luxI gene

The coding sequence in the DNA of __________ is normally continuous; that is, it is not interrupted by noncoding sequences. a) most insects b) mammals c) bacteria d) plants

c) bacteria

Key sequences exist within promoters, which vary somewhat among various promoters but are sufficiently constant that they can be represented by a sequence of bases most often found at each position. These representations are called __________ sequences. a) convergence b) idealized c) consensus d) common

c) consensus

Enzymes that are expressed at a constant level all the time are said to be . a) inducible b) repressible c) constitutive d) attenuated

c) constitutive

The most effective strategy to decrease antibiotic resistance in bacteria is _________. a) increasing vaccination practices b) developing new antibiotics c) decreasing antibiotic use

c) decreasing antibiotic use

Enzymes catalyze a reaction by _________. a) decreasing the amount of energy released by the reaction b) increasing the amount of energy released by the reaction c) decreasing the activation energy of the reaction d) increasing the activation energy of the reaction

c) decreasing the activation energy of the reaction

The most specific term usually used to describe a substance in a biological system that increases the rate of a reaction without being permanently changed by the reaction is a(n) _________. a) catalyzer b) reductant c) enzyme d) rate increaser

c) enzyme

With the E. coli trp operon where both repression and attenuation occur, the extent of regulation achieved by repression is _________ the extent of regulation achieved by attenuation. a) the same as b) less than c) greater than d) Repression is not used in the regulation of the E. coli trp operon.

c) greater than

A complete enzyme that consists of a protein component and a nonprotein component is called a(n) _________. a) apoenzyme b) heteroenzyme c) holoenzyme d0 multienzyme

c) holoenzyme

Vancomycin _________ a) inhibits the transglycosylase reaction in peptidoglycan biosynthesis b) interferes with the action of the lipid carrier that transports peptidoglycan precursors across the plasma membrane c) inhibits the transpeptidation reaction in peptidoglycan biosynthesis d) blocks the addition of the pentapeptide chain during peptidoglycan biosynthesis

c) inhibits the transpeptidation reaction in peptidoglycan biosynthesis

The lac operon is expressed when glucose is _________. a) high and lactose is present b) high and lactose is absent c) low and lactose is present d) glucose is low, regardless of the presence or absence of lactose e) low and lactose is absent

c) low and lactose is present

The minimal lethal concentration (MLC) is the _________ a) lowest concentration of a drug that prevents growth of a particular pathogen b) highest concentration of a drug that prevents growth of a particular pathogen c) lowest concentration of a drug that kills a particular pathogen d) highest concentration of a drug that kills a particular pathogen

c) lowest concentration of a drug that kills a particular pathogen

The Shine-Dalgarno sequence is found on the __________. a) large ribosomal subunit b) small ribosomal subunit c) mRNA d) initiator tRNA e) IF-3

c) mRNA

During the stringent response, ppGpp-regulated genes for amino acid biosynthesis form a/an open initiation complex. a) unstable b) less stable c) more stable d) completely stable

c) more stable

Pick the most complete answer below for regulation of a multibranched pathway. Regulation of a multibranched pathway can be due to feedback inhibition ___________. a) of the initial pacemaker enzyme b) of the branchpoint enzymes c) of the initial enzyme, the branchpoint enzyme, and by the presence of isoenzymes d) of the initial enzyme and the branchpoint enzyme e) by the presence of isoenzymes

c) of the initial enzyme, the branchpoint enzyme, and by the presence of isoenzymes

Enzymes lower the energy of activation required for a biochemical reaction to take place. They achieve this by __________. a) reducing the number of substrates at the active site to limit competition b) increasing the frequency of collisions between substrates c) orienting the substrates such that they require less energy to reach the transition state d) maintaining a rigid shape when the substrate binds to conserve the active site

c) orienting the substrates such that they require less energy to reach the transition state

In allosteric regulation, effector molecules usually bind _________. a) reversibly and covalently b) irreversibly and covalently c) reversibly and noncovalently d) irreversibly and noncovalently

c) reversibly and noncovalently

Some RNA molecules are able to catalyze a reaction that cuts out a fragment of their own nucleic acid molecule then joins the loose ends back together again. This describes the action of __________. a) denaturation b) RNA polymerase c) ribozymes d) enzymes

c) ribozymes

Metabolic channeling involves the localization of __________ in different parts of a cell in order to influence the activity of metabolic pathways. a) activators b) repressors c) substrates and enzymes d) inhibitors

c) substrates and enzymes

The E. coli lac operon has ________ operator sequences. a) one b) two c) three d) four

c) three

At the E site _________. a) transcription occurs b) anticodons match with codons c) transfer RNA is released d) peptide bonds are formed

c) transfer RNA is released

Comparing two-component signal transduction systems and phosphorelay systems, _________. a) the two processes differ only in that phosphorelay systems are more widespread than two-component signal transduction systems b) two-component signal transduction systems mediate the transfer of multiple phosphoryl groups between a variety of sensor kinases, whereas phosphorelay systems transfer a single phosphoryl group to a response regulator c) two-component signal transduction systems mediate the transfer of a single phosphoryl group from a sensor kinase to a response regulator, whereas phosphorelay systems transfer multiple phosphoryl groups between a series of proteins d) phosphorelay systems mediate the transfer of a single phosphoryl group from a sensor kinase to a response regulator, whereas two-component signal transduction systems transfer multiple phosphoryl groups between a series of proteins

c) two-component signal transduction systems mediate the transfer of a single phosphoryl group from a sensor kinase to a response regulator, whereas phosphorelay systems transfer multiple phosphoryl groups between a series of proteins

The hypothesis that the proton motive force drives ATP synthesis is called the _________hypothesis.

chemiosmotic

In metabolic channeling, enzymes and metabolites are differentially distributed among separate cell structures or organelles and this different distribution is called _________.

compartmentation

An inhibitor that directly competes with the substrate at an enzyme's catalytic site and prevents the enzyme from forming product is called a _________ inhibitor.

competitive

ATP is formed by exergonic reactions and then used to drive endergonic reactions so ATP is considered a link or _________ _________ between these reactions.

coupling agent

How many RNA codons encode 60 amino acids? a) 180 b) 30 c) 20 d) 60

d) 60

Cell-to-cell communication by quorum sensing has been shown to be important in the regulation of genes needed for _________. a) virulence b) biofilm production c) plasmid transfer d) All of the choices are correct.