MICRO EXAM 3

the presence of the F plasmid in a cell alters which of the following properties of a cell? .the ability to mobilize DNA for transfer the ability to create Hfr strains the ability to generate a pilus the ability to replicate DNA alteration of cell surface receptors so the cell cannot act as a recipient in conjugation.

.the ability to mobilize DNA for transfer the ability to create Hfr strains the ability to generate a pilus alteration of cell surface receptors so the cell cannot act as a recipient in conjugation.

Which of the following features are common to transformation, transduction, and conjugation?(1) unidirectional transfer of genes(2) incomplete gene transfer(3) homologous recombination(4) meiosis occurring in the recipient 1, 2, 4 1, 2, 3 1, 2 3, 4

1, 2, 3

Using quorum sensing, how do bacteria know when there are sufficient numbers present to express a specific gene? A high concentration of autoinducer inside the cell triggers the two-component system to turn on transcription of the specific gene. A low concentration of an autoinducer in the cell triggers the two-component system to turn on transcription of the specific gene. A high concentration of autoinducer outside the cell triggers the two-component system to turn on transcription of the specific gene. A low concentration of an autoinducer outside the cell triggers the two-component system to turn on transcription of the specific gene.

A high concentration of autoinducer inside the cell triggers the two-component system to turn on transcription of the specific gene.

Which of the following conditions favors a lysogenic life cycle in bacteriophages? Having ssDNA. Having ssRNA. The presence of abundant hosts. A lack of host bacteria.

A lack of host bacteria.

All of the following are characteristic of suppressor mutations EXCEPT Mutation in another gene restores the function of the original mutated gene. Mutation in another gene produces an enzyme that replaces the mutated one. A mutation elsewhere in same gene restores function. A mutation at same site as the original mutation restores function. All of the items are characteristic of suppressor mutations.

A mutation at same site as the original mutation restores function.

Bacteria can regulate gene expression due to changes in the environment. How are these changes communicated to the cell? A response regulator on the cell membrane recognizes the change and transfers the information to a sensor kinase in the cytoplasm. A sensor kinase in the cytoplasm recognizes a change and transfers the information to a response regulator on the cell membrane. A sensor kinase on the cell membrane recognizes the change and transfers the information to a response regulator in the cytoplasm. A sensor kinase on the cell membrane recognizes the change and transfers the information to the repressor or inducer molecule, which then binds to DNA.

A sensor kinase on the cell membrane recognizes the change and transfers the information to a response regulator in the cytoplasm.

What is the benefit, for a virus, to be a temperate or lysogenic virus? A single infection event can produce millions of new viral particles instead of hundreds of viral particles. A single infection event can allow the virus to live in the host cell indefinitely. A single infection even can allow other host cells to be infected by the same virus. A single infection event can produce hundreds of new viral particles.

A single infection event can produce millions of new viral particles instead of hundreds of viral particles.

which of the following statements regarding archaeal viruses are true? A. The majority of archaeal viruses do not lyse the host cell. B. Archaeal viruses are morphologically more diverse than Bacterial ones. C. Many archaeal viruses are enveloped.

A. The majority of archaeal viruses do not lyse the host cell. B. Archaeal viruses are morphologically more diverse than Bacterial ones. C. Many archaeal viruses are enveloped.

which of the following regarding the arbitrium system are true? High concentrations of arbitrium promote the lytic pathway. AimX silences expression of the phage cI repressor. Arbitrium is a quorum-sensing signal. Arbitrium inhibits expression of aimX. Different phages encode homologues of this system with different signal peptides.

AimX silences expression of the phage cI repressor. Arbitrium is a quorum-sensing signal. Arbitrium inhibits expression of aimX. Different phages encode homologues of this system with different signal peptides.

genetic regulation

All genes are not expressed or transcribed at the same rate. Some genes are only expressed under specific environmental conditions. There are methods to turn this expression off and on, when the environmental conditions change.

Explain how small RNA (sRNA) molecules can regulate translation of a piece of mRNA. sRNAs can base pair to mRNA and block translation. sRNAs can change the secondary structure of mRNA. sRNAs can increase degradation rate of mRNA. All of the listed responses are correct. sRNAs can decrease degradation rate of mRNA.

All of the listed responses are correct.

Bidirectional transfer of DNA during conjugation is seen in __________. gram-negative bacteria Archaea gram-positive bacteria proteobacteria

Archaea

All of the following are required for homologous recombination EXCEPT RecA All of these are required for homologous recombination. Endonuclease Long regions of sequence homology Att site

Att site

Which of the following events happens in specialized transduction? Bacterial genes adjacent to the site where the phage DNA integrates are transduced. Phage genes adjacent to the site of integration on the bacterial chromosome are transduced. Random bacterial genes found on chromosomes and plasmids are transduced. Genes found on plasmids, which can result in the formation of more transducible cells, are transduced.

Bacterial genes adjacent to the site where the phage DNA integrates are transduced.

initiation of translation

Before translation begins, the ribosomal subunits, proteins, and mRNA must assemble to form the 70S ribosomal complex.

Phosphorylation of ________ regulates which direction a flagellum rotates, thus controlling whether an organism runs or tumbles. CheAW CheB CheZ CheY

CheY

Tumbling during chemotaxis in E. coli is regulated by __________. CheY CheB CheY-P CheZ

CheY-P

All of the following are true of natural competence EXCEPT Competence occurs with high efficiency in E coli. Competence is induced during certain growth phases. Competence requires special DNA uptake, DNA binding, and integration proteins. Competence is required for transformation. Competence rarely occurs with high efficiency in nature.

Competence occurs with high efficiency in E coli.

Drugs targeting which of the following would have the least selective toxicity? 70S ribosome RNA polymerase peptidoglycan DNA major groove LPS

DNA major groove

Spontaneous mutations commonly arise during which process? transformation transcription DNA replication translation

DNA replication

What cellular component is NOT a molecular chaperone? GroEL DnaK DnaJ DnaA GroES

DnaA

T4 genes are transcribed by host RNA polymerase, yet the transcription of T4 genes is carefully controlled so that groups of T4 genes are transcribed at specific times after infection. How is this accomplished? Rolling circle replication of the viral genome ensures that the genes are available for transcription in the correct order. Early and middle T4 genes encode proteins that modify the activity of sigma factors and host RNA polymerase to regulate the expression of T4 genes. Early T4 genes encode proteolytic enzymes that destroy the host RNA polymerase. Subsequently a viral polymerase is created that transcribes the middle and late genes in the correct order. Each group of T4 genes has a different promoter that indicates that order in which they should be transcribed in based on the affinity of the promoter for the host RNA polymerase.

Early and middle T4 genes encode proteins that modify the activity of sigma factors and host RNA polymerase to regulate the expression of T4 genes.

Define what an effector is in genetic regulation. Effectors are small molecules that only repress transcription of a specific gene. Effectors are another name for the repressor protein that binds to DNA in negative control. Effectors are small molecules that induce or repress transcription of a specific gene. Effectors are small molecules that only induce transcription of a specific gene.

Effectors are small molecules that induce or repress transcription of a specific gene.

Membrane transport proteins are required for which mode(s) of antibiotic resistance? Modification of a porins Efflux pumps, beta-lactamases, and modification of porins Efflux pumps and modification of porins Efflux pumpsBeta-lactamases

Efflux pumps, beta-lactamases, and modification of porins

Consider the following experiment. First, large populations of two mutant strains of Escherichia coli are mixed, each requiring a different, single amino acid. After plating them onto a minimal medium, 45 colonies grew. Which of the following may explain this result? The colonies may be due to recombination. The colonies may be due to back mutation (reversion). Either A or B is possible. Neither A nor B is possible.

Either A or B is possible.

which of the following are required for homologous recombination? RecA Endonuclease Long regions of sequence homology Att site

Endonuclease Long regions of sequence homology RecA

Which of the following is (are) used by microorganisms to become resistant to a particular drug? Select all that apply. Enzymatic inactivation of the drug Exclusion of the drug from the cell Modification of the drug target An alternate metabolic pathway that bypasses the drug-sensitive step

Enzymatic inactivation of the drug Exclusion of the drug from the cell Modification of the drug target An alternate metabolic pathway that bypasses the drug-sensitive step

Which of the following elements is NOT required for the formation of Hfr cells? pilin protein F plasmid F factor origin of transfer

F plasmid

What is the difference between an F+ and an Hfr bacterium? F+ bacteria have a nonintegrated F plasmid, while Hfr bacteria have an F plasmid that is integrated into their main chromosome. F+ bacteria have an F plasmid that includes some nuclear genes, while Hfr (high frequency recombinant) bacteria have an F plasmid with only the essential genes for conjugation. F+ bacteria have a plasmid with only the essential genes for conjugation, while Hfr (high frequency recombinant) bacteria have an F plasmid that includes some nuclear genes. F+ bacteria have an integrated F plasmid, while Hfr bacteria have a nonintegrated F plasmid.

F+ bacteria have a nonintegrated F plasmid, while Hfr bacteria have an F plasmid that is integrated into their main chromosome.

A mutation occurs so that that DnaK binds more tightly to RpoH. Which of the following would be an outcome of this mutation? The heat shock response would maintain unchanged. The cell would grow faster More heat shock genes would be transcribed. Fewer misfolded proteins would be refolded. More misfolded proteins would be refolded.

Fewer misfolded proteins would be refolded.

How can flagellar motion be regulated?

Flagella can be regulated by systems such as catabolite repression. For example, the presence of glucose inhibits the synthesis of flagella. However, flagella begin to move because of a proton motive force powering the protein flagellar motor. Synthesis of new flagella components is not required for motion to occur.

How is generalized transduction different from specialized transduction? Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage. Specialized transduction uses animal viruses instead of bacteriophage. Generalized transduction is initiated by a lysogenic bacteriophage; specialized transduction is initiated by a lytic phage. Only one specific host gene is transferred in both specialized transduction and generalized transduction.

Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.

Which of the following describes the essential parts of all viruses? Genetic material (RNA or DNA), a protein capsid, and an envelope Genetic material (RNA and DNA) and a protein capsid Genetic material (RNA or DNA), a protein capsid, an envelope, and enzymes Genetic material (RNA or DNA) and a protein capsid

Genetic material (RNA or DNA) and a protein capsid

Which cellular components are molecular chaperones? GroEL DnaK DnaJ DnaA GroES

GroEL DnaK DnaJ GroES

Which of the following is most similar to lysogeny? F' state F- state Hfr state F+ state

Hfr state

Which of the following regarding the arbitrium system is FALSE? High concentrations of arbitrium promote the lytic pathway. AimX silences expression of the phage cI repressor. Arbitrium is a quorum-sensing signal. Arbitrium inhibits expression of aimX. Different phages encode homologues of this system with different signal peptides.

High concentrations of arbitrium promote the lytic pathway.

viral infection

In order to infect cells, viruses have to attach to the cell. They do this by finding appropriate receptors. Receptors differ in different species and even in different cells within a single organism. That is why some viruses can cause infection only with particular types of exposure (e.g., HIV cannot cause infection through a handshake) and may infect only particular tissues (e.g., viral upper respiratory infections are located in the tissues of the upper respiratory tract).

Which of the following statements is FALSE? If an Hfr cell is mated with an F- cell, the F- cell will remain F-. In specialized transduction, virtually any genetic marker can be transferred from donor to recipient. Lysogeny confers resistance to infection by viruses of the same type. Pathogenesis in Corynebacterium diphtheriae is due to phage conversion.

In specialized transduction, virtually any genetic marker can be transferred from donor to recipient.

Mutation rates are similar in Bacteria and Archaea, yet certain stressful conditions cause mutation rates to increase. Why is the mutation rate not constant and close to zero all of the time? Increased mutation rates can be advantageous in rapidly changing environments because some random mutations may be useful for survival. The increased mutation rate under stressful conditions is an indication that the microorganisms can no longer replicate their DNA properly and are about to die. Microorganisms carefully control the mutation rate of their DNA to match the environmental conditions and maximize evolution. Constant mutation rates would halt evolution completely.

Increased mutation rates can be advantageous in rapidly changing environments because some random mutations may be useful for survival.

which of the following are characteristic of suppressor mutations? Mutation in another gene restores the function of the original mutated gene. Mutation in another gene produces an enzyme that replaces the mutated one. A mutation elsewhere in same gene restores function. A mutation at same site as the original mutation restores function.

Mutation in another gene restores the function of the original mutated gene. Mutation in another gene produces an enzyme that replaces the mutated one. A mutation elsewhere in same gene restores function.

Are viruses that infect Archaea different from bacterial viruses? Yes; they have only DNA genomes. Yes; they do not have protein coats because of the extreme conditions where they live. No; they consist of nucleic acid and protein like other bacterial viruses. Yes; the structure of archaeal viruses is always completely different from other bacterial viruses.

No; they consist of nucleic acid and protein like other bacterial viruses.

sRNAs

Noncoding RNA molecules are never translated to protein. can regulate the rate of translation of a piece of mRNA.

All of the following are functions of Cas proteins EXCEPT Process pre-CRISPR RNAIntegrate new spacers into the CRISPR gene Use RNA transcribed from segments of foreign DNA to recognize and destroy foreign DNA Stop viral attacks before they can take over the cell None of the functions are incorrect

None of the functions are incorrect

Which of the following statements regarding archaeal viruses is false? A. The majority of archaeal viruses do not lyse the host cell. B. Archaeal viruses are morphologically more diverse than Bacterial ones. C. Many archaeal viruses are enveloped. None of the statements are false. A and C are false.

None of the statements are false.

Consider the following statements: I. Quorum sensing is only seen in gram-positive organisms. II. Molecules called autoinducers spread freely across the microbial membrane. Only statement I is true. Only statement II is true. Both statements are true. Neither statement is true.

Only statement II is true.

Consider the Pseudomonas aeruginosa cells discussed in the introductory passage. How might chemotaxis and adaptation be interacting in this system? Select the best answer. Over time, the bacteria show increasing attraction to the damaged and dying epithelial cells. Adaptation to new chemicals allows them to begin to respond to signals from other locations Over time, the bacteria show adaptation and epithelial cells begin to die. Newly damaged cells emit signals and the bacteria exhibit chemotaxis towards them. Over time, the dying epithelial cells produce repellants that cause chemotaxis away from the area. This allows the bacteria to reach new areas where they can find fresh nutrients. Over time, the bacteria exhibit negative chemotaxis away from toxic chemicals produced by the damaged cells. They later show adaptation to these chemicals and are able to return.

Over time, the bacteria show adaptation and epithelial cells begin to die. Newly damaged cells emit signals and the bacteria exhibit chemotaxis towards them.

which of the following are true regarding prokaryotic protein secretion? Proteins are inserted into the cell membrane by co-translational Sec secretion. Sec and Tat pathways both are fueled by ATP hydrolysis. The basic information for locating a protein in the right place is contained within its sequence. Proteins with complex cofactors, such as iron-sulfur proteins, are Tat secreted. Some gram-negative secretion systems do not require Sec or Tat.

Proteins are inserted into the cell membrane by co-translational Sec secretion. The basic information for locating a protein in the right place is contained within its sequence. Proteins with complex cofactors, such as iron-sulfur proteins, are Tat secreted. Some gram-negative secretion systems do not require Sec or Tat.

RNA genomes have a higher mutation rate than DNA genomes. This is because __________. RNA repair mechanisms do not exist RNA is easily inactivated RNA repair mechanisms are better than DNA repair mechanisms RNA repair mechanisms are inefficient

RNA repair mechanisms do not exist

RNA viruses require which of the following enzymes to replicate their genome? RNA replicase reverse transcriptase DNA polymerase Cas proteins RNA polymerase

RNA replicase

RNA viruses require which of the following enzymes to replicate their genome? RNA replicase Cas proteins DNA polymerase RNA polymerase reverse transcriptase

RNA replicase

DNA damage activates RecA. How, then, is the SOS repair system initiated? RecA associates with UvrA protein, assisting in the removal of LexA from the operator. RecA causes self-cleavage of LexA, thus inactivating it and preventing its binding to the operator. RecA competes for binding with LexA, forcing the dissociation of this repressor from the operator. RecA associates with LexA, creating secondary structures that force its dissociation from the operator.

RecA causes self-cleavage of LexA, thus inactivating it and preventing its binding to the operator.

All of the following are true regarding prokaryotic protein secretion EXCEPT Proteins are inserted into the cell membrane by co-translational Sec secretion. Sec and Tat pathways both are fueled by ATP hydrolysis. The basic information for locating a protein in the right place is contained within its sequence. Proteins with complex cofactors, such as iron-sulfur proteins, are Tat secreted. Some gram-negative secretion systems do not require Sec or Tat.

Sec and Tat pathways both are fueled by ATP hydrolysis.

You expose a bacterial strain to DNA containing bacitracin resistance. Then you plate the resulting culture onto a rich medium containing bacitracin. This is an example of Neither selection nor screening Both selection and screening Selection Screening

Selection

Which of the following are true regarding DNA-binding proteins? Select all that apply. Small molecules influence binding of regulatory proteins to DNA. Most DNA-binding proteins interact with DNA in a sequence-specific manner. The lac repressor contains the helix-turn-helix structure. The minor groove of DNA is the main site of protein binding. Homodimeric regulatory proteins interact with inverted repeats on DNA.

Small molecules influence binding of regulatory proteins to DNA. Most DNA-binding proteins interact with DNA in a sequence-specific manner. The lac repressor contains the helix-turn-helix structure. Homodimeric regulatory proteins interact with inverted repeats on DNA.

Which statement best explains why positively controlled genes have weak promoters and need an activator protein to help the RNA polymerase bind? So transcription stops when the substrate for the gene product is present. So transcription occurs only when the substrate for the gene product is present. So translation only occurs when the substrate for the gene product is present. So translation only stops when the substrate for the gene product is present.

So transcription occurs only when the substrate for the gene product is present.

constitutuve genes

Some genes are expressed no matter what the cellular conditions

negative control

Some genes are only expressed when needed, while others can be turned off to conserve energy

One hypothesis that has been proposed to explain the development of viruses suggests that viruses were beneficial because they allowed for rapid gene transfer, especially in prokaryotic cells, and therefore increased genetic diversity. Temperate viruses could have increased horizontal gene transfer between prokaryotic cells and potentially increased their fitness. With respect to this hypothesis, why would it matter whether the bacteriophages were temperate or virulent? Temperate phages don't immediately kill their hosts. Virulent phages are capable of lysogeny, and their genetic material can be integrated into the host genome, causing damage rather than increasing fitness. Temperate bacteriophages are capable of both horizontal and vertical gene transfer, allowing a wide range of ways to increase genetic diversity. Virulent bacteriophages are not capable of either. Temperate phages are capable of lysogeny, and their genetic material can be integrated into the host genome, causing damage rather than increasing fitness.

Temperate phages don't immediately kill their hosts.

What is the difference between a temporal and a spatial gradient?

Temporal gradients vary over time while spatial gradients vary between one location and another.

Which statement describes the difference between the normal neuron protein PrPC and the pathogenic version PrPSc? PrPC is just a protein and the PrPSc is a protein with nucleic acid inside. The PrPC protein contains more beta sheets while the PrPSc protein contains more alpha helices. The three-dimensional conformation is identical, but the amino acid sequence is different. The amino acid sequence is identical, but the three-dimensional conformation is different.

The amino acid sequence is identical, but the three-dimensional conformation is different.

Two-component regulatory systems rely on a balance of phosphorylation and dephosphorylation of sensor kinases and response regulators. If the response regulator became permanently phosphorylated due to lack of phosphatase activity, which of the following would occur? The cell would become insensitive to the environmental stimulus. The cell would not be able to "reset" its response cycle. The operon controlled by the response regulator would be always transcribed or never transcribed, depending upon the regulatory role of the response regulator. The cell would become more sensitive to the environmental stimulus.

The cell would become insensitive to the environmental stimulus. The cell would not be able to "reset" its response cycle. The operon controlled by the response regulator would be always transcribed or never transcribed, depending upon the regulatory role of the response regulator.

Two-component regulatory systems rely on a balance of phosphorylation and dephosphorylation of sensor kinases and response regulators. If the response regulator became permanently phosphorylated due to lack of phosphatase activity, all of the following would occur EXCEPT The cell would become insensitive to the environmental stimulus. The cell would not be able to "reset" its response cycle. The operon controlled by the response regulator would be always transcribed or never transcribed, depending upon the regulatory role of the response regulator. The cell would become more sensitive to the environmental stimulus.

The cell would become more sensitive to the environmental stimulus.

The general steps of the viral lifecycle are similar in most viruses. One major exception, however, is entry into the host cell. How does this step differ between an animal cell and E coli? The entire virion is taken into an animal cell, but only the viral genome enters E coli. The virion randomly attaches to E coli, but viral binding to a specific receptor is required for entry into animal cells. The virion fuses to the bacterial cell membrane of E coli, while the genome is injected into an animal cell. The entire virion enters E coli, but only the nucleic acid is taken up by animal cells.

The entire virion is taken into an animal cell, but only the viral genome enters E coli.

What would be the most likely effect of a mutation in the operator of a lac operon? The genes would be constitutively expressed. The repressor would not be produced. Beta-galactosidase would not be produced. Regulation would occur normally.

The genes would be constitutively expressed

In negative control of transcription by the lac operon, how does the presence of an inducer affect transcription? The inducer prevents the repressor from binding to the operator. The inducer causes the repressor to bind to the operator. The inducer does not bind to the operator. The inducer binds to the operator.

The inducer prevents the repressor from binding to the operator.

Which of the following conclusions can be made if two identical insertion sequences are identified in separate locations on a chromosome? The insertion sequence was transferred via conservative transposition. The insertion sequence was transferred via simple transposition. The insertion sequence was a "cut-and-paste" transposon. A mutation occurred during transposition of the insertion sequence. The insertion sequence was transferred via replicative transposition.

The insertion sequence was transferred via replicative transposition.

A single base substitution happens to cause a nonsense mutation early in the gene for a protein. What will be the result? The protein will be truncated a small amount, but is unlikely to function normally. The protein will be truncated a small amount, but is likely to function normally. The protein will be truncated so much that it is unlikely to function normally. The protein will be truncated a great deal, but is likely to function normally.

The protein will be truncated so much that it is unlikely to function normally.

signal transduction

There are methods for a cell to receive messages from the surrounding environment and transmit those messages to the appropriate site in the cell

All of the following are characteristic of Sec secretion systems except Translocation requires energy. They translocate folded proteins across the cell membrane. Translocation requires a signal sequence on the polypeptide. They are highly conserved and are universal in prokaryotes. Translocation can occur during or after translation.

They translocate folded proteins across the cell membrane.

Regulation by induction and repression are called negative control because __________. Translation proceeds in the presence of the repressor protein. Translation proceeds in the absence of the repressor protein. Transcription proceeds in the presence of the repressor protein. Transcription proceeds in the absence of the repressor protein.

Transcription proceeds in the absence of the repressor protein.

If chromosomal DNA from a host is the only type of DNA carried by a transducing particle, what can be concluded regarding transduction in this case? Transduction is specialized. Transduction is generalized. Transduction could be generalized or specialized depending on the phage involved. Transduction is neither generalized nor specialized.

Transduction is generalized.

which of the following are characteristic of Sec secretion systems? Translocation requires energy. They translocate folded proteins across the cell membrane. Translocation requires a signal sequence on the polypeptide. They are highly conserved and are universal in prokaryotes. Translocation can occur during or after translation.

Translocation requires energy. Translocation requires a signal sequence on the polypeptide. They are highly conserved and are universal in prokaryotes. Translocation can occur during or after translation.

All of the following statements regarding protein secretion are true EXCEPT Type III, IV and VI secretion systems require ATP. Type I, II and V secretion systems are Sec- or Tat-dependent. Types I through VI secretion systems specifically recognize substrates based on amino acid sequence. Type IV secretion systems can transport DNA in addition to proteins. Type III, IV and VI secretion systems secrete molecules into another cell.

Type I, II and V secretion systems are Sec- or Tat-dependent.

Which of the following statements regarding protein secretion are true? Type III, IV and VI secretion systems require ATP. Type I, II and V secretion systems are Sec- or Tat-dependent. Types I through VI secretion systems specifically recognize substrates based on amino acid sequence. Type IV secretion systems can transport DNA in addition to proteins. Type III, IV and VI secretion systems secrete molecules into another cell.

Type III, IV and VI secretion systems require ATP. Types I through VI secretion systems specifically recognize substrates based on amino acid sequence. Type IV secretion systems can transport DNA in addition to proteins. Type III, IV and VI secretion systems secrete molecules into another cell.

The codon for phenylalanine is UUU. Which of the following codons also most likely encodes for phenylalanine? CUU AAA AUG UUC AUU

UUC

Which of the following examples is an example of lysogenic conversion? T4 phages infect E. coli bacteria and are resistant to destruction by restriction enzymes. An RNA virus infects a cell and causes the production of new viruses. Vibrio cholerae bacteria produce cholera toxin when infected with a phage. A lambda phage infects E. coli and enters the lytic cycle.

Vibrio cholerae bacteria produce cholera toxin when infected with a phage.

Viruses differ from living organisms in that Viruses are acellular and all living things are made up of cells Viruses have DNA or RNA, not both Viruses depend on their host to synthesize the essential components of new viruses (e.g., genetic material and proteins), while living organisms are capable of synthesizing these components even if they require a host for food, shelter, or other necessities. Viruses are obligate parasites and no living organisms are obligate parasites.

Viruses are acellular and all living things are made up of cells Viruses have DNA or RNA, not both Viruses depend on their host to synthesize the essential components of new viruses (e.g., genetic material and proteins), while living organisms are capable of synthesizing these components even if they require a host for food, shelter, or other necessities. .

All of the following indicate a way in which viruses differ from living organisms except Viruses are acellular and all living things are made up of cells Viruses have DNA or RNA, not both Viruses depend on their host to synthesize the essential components of new viruses (e.g., genetic material and proteins), while living organisms are capable of synthesizing these components even if they require a host for food, shelter, or other necessities. Viruses are obligate parasites and no living organisms are obligate parasites.

Viruses are obligate parasites and no living organisms are obligate parasites.

Which of the following is true about viral infection? Viruses have what is needed to infect a host cell; they do not need anything specific from the host cell in order to cause infection and therefore can infect a wide range of cells. Viruses are very specific in which cells they infect. For a virus to be taken up by a cell, it must find a cell with appropriate receptors on the surface. It cannot be taken up by cells without the appropriate receptors. Viruses can infect any cells within a large group, but they are not more specific than that. For example, there are plant viruses that can affect many types of plants, bacteriophages that affect many types of bacteria, and animal viruses that affect a range of viruses. Viruses can infect any cell in a particular species; it does not matter which tissue they infect as long as the species (or group of similar species) is correct.

Viruses are very specific in which cells they infect. For a virus to be taken up by a cell, it must find a cell with appropriate receptors on the surface. It cannot be taken up by cells without the appropriate receptors.

lysogenic conversion

When a bacteriophage integrates its genetic material into a bacterial chromosome (a prophage) during the lysogenic life cycle

In Archaea, some regulatory proteins that control transcription can act as repressors, activators, or both. How is this possible? When acting as an activator, the regulatory protein always has an inducer bound to its allosteric site; as a repressor it does not. The regulatory protein is only synthesized when it is needed to be an activator, not when repression is required. When acting as an activator, the regulatory protein has an inducer bound to its allosteric site; when acting as a repressor it has a corepressor bound to it. When acting as a repressor, the regulatory protein binds to a different DNA sequence than when it is acting as an activator.

When acting as a repressor, the regulatory protein binds to a different DNA sequence than when it is acting as an activator.

Which of the following examples describes a type of catabolite repression? The presence of abundant tryptophan inhibits the trp operon. A mutation in the promoter of the lac operon prevents the expression of the genes needed for the bacterium to utilize lactose. Allolactose binds to a repressor, preventing it from binding to the operator of the lac operon. When glucose is present, the lac operon is inhibited.

When glucose is present, the lac operon is inhibited.

One group of chemical mutagens includes the base analogs. How do these lead to mutations? Base analogs push apart and distort the double helix. This distortion can lead to insertions and deletions (including frameshift mutations). They lead to the formation of pyrimidine dimers. When replication occurs, complementary base pairing may fail because the base analog may not be treated in the same way as the base that it replaced. They lead to alkylation, which can lead to substitutions.

When replication occurs, complementary base pairing may fail because the base analog may not be treated in the same way as the base that it replaced.

Which organism would likely harbor the MOST two-component regulatory systems? a parasitic bacterium living inside another organism an organism capable of quorum sensing an archaeon living in an extreme environment a bacterium occupying a heterogeneous niche with high nutrient mixing

a bacterium occupying a heterogeneous niche with high nutrient mixing

Bacteriophages T2 and T4 have a complex structure consisting of __________. a cylindrical capsid RNA, DNA, and protein an icosahedral capsid a capsid with head, tail, and tail fibers

a capsid with head, tail, and tail fibers

signs of chemotaxis

a cell is exhibiting mostly runs CheY is unable to bind to the flagellar motor CheB-P is present in high concentrations

Restriction is the viral process whereby the virus prevents other viruses from entering the cell. the viral process whereby a host's DNA ceases normal functioning. a general host mechanism to prevent virus particles from further infective action. a general host mechanism to prevent the invasion of foreign nucleic acid.

a general host mechanism to prevent the invasion of foreign nucleic acid.

catabolite repression

a global control process (i.e., it affects many operons) in which the presence of a specific carbon source (often glucose) inhibits operons for other catabolic processes. Sometimes organisms have several sugars available to them at once. When this occurs, the sugar that is easiest to degrade is used first, normally glucose. Glucose is easiest to degrade because the genes to break it down are constitutively expressed. After the first sugar is used up, other genes are turned on to break down the next sugar.

One way that regulation is often studied is by examining the effects of mutations. For example, mutations within the parts of the lac operon have been well studied. Which of these mutants would be considered a constitutive mutant? a mutation that disables the promoter for the operon a mutation that disables the repressor a mutation in the gene for beta-galactosidase a mutation in the gene for beta-galactosidase permease

a mutation that disables the repressor

A virus particle is made up of __________. DNA only protein only RNA only a nucleic acid and protein

a nucleic acid and protein

F plasmid

a plasmid with genes for conjugation. It allows the cell to produce a pilus and to transfer a plasmid while inhibiting another cell from connecting with a pilus. When a plasmid is transferred from one cell to another through a pilus, conjugation occurs.

What do virus particles attach to? the cytoplasmic membrane the nucleus the bacterial cell wall a receptor on the cell surface

a receptor on the cell surface

A point mutation refers to mutations involving the deletion of a base pair (microdeletion). a substitution, deletion, or addition of one base-pair. the gain of a base pair (microinsertion). a base-pair substitution.

a substitution, deletion, or addition of one base-pair.

The three stages of translation, initiation, elongation, and termination, __________. all require at least one protein cofactor and all require GTP all require base pairing between two RNAs all require ATPall require at least one protein cofactor and base pairing between two RNAs all require at least one protein cofactor and all require ATP

all require at least one protein cofactor and all require GTP

runs

allow directed movement

A prophage replicates independently of its host while the lytic genes are not expressed. independently of its host while the lytic genes are expressed. along with its host while the lytic genes are not expressed. along with its host while the lytic genes are expressed.

along with its host while the lytic genes are not expressed.

Transcription of heat shock response genes is controlled by sRNAs. alternate sigma factors. activator proteins. a two-component regulatory system.repressor proteins.

alternate sigma factors.

Global regulatory systems include all of the following EXCEPT stringent response. heat shock response. stationary phase. catabolite repression. amino acid synthesis.

amino acid synthesis.

signs of adaptation

an MCP is fully methylated a cell is exhibiting mostly tumbles CheB is not phosphorylated an MCP is fully unmethylated

What is Cas9 and what does it do? a protein that functions in DNA repair and recombination an enzyme that cuts both strands of DNA at sites specified by a guide RNA a DNA sequence that binds the Cas9 protein an RNA molecule that binds to target DNA via complementary base pairing

an enzyme that cuts both strands of DNA at sites specified by a guide RNA

In the laboratory, animal viruses are generally grown in __________. culture media plants animal cell culture bacteria

animal cell culture

Generally, the rate of spontaneous mutation in bacteria is __________. approximately one in a million approximately one in a thousand approximately one in a hundred approximately one in ten

approximately one in a million

Microbial mats differ from biofilms in that they __________. are found only attached to surfaces contain more than one species of microorganism in the community are currently found only in extreme habitats have different environmental conditions at various depths within the community

are currently found only in extreme habitats

What is the role of quorum-sensing systems? assessing species in a population assessing and adjusting population density assessing cell type in a population assessing the health of a population

assessing and adjusting population density

Methyl-accepting chemotaxis protein

associates with a sensor kinase and a coupling protein to trigger autophosphorylation.

Which regulatory mechanism does NOT depend on a conformational change in protein/enzyme structure to change activity? attenuation positive control negative control feedback inhibition catabolite repression

attenuation

In quorum sensing, the small signal molecule that is released into the environment by bacterial cells is called a(n) __________. repressor activator auto-inducer riboswitch

auto-inducer

A mutant organism that has a nutritional requirement for growth is called a(n) __________. heterotroph prototroph auxotroph wild type

auxotroph

Regulation of transcription in Archaea resembles that of __________. eukarya bacteria algae animals

bacteria

Transcriptional control in Archaea most closely resembles that in ________ and utilizes ________. eukaryotes; regulatory proteins bacteria; regulatory proteins bacteria; transcription factors eukaryotes; transcription factors

bacteria; regulatory proteins

The cellular basis for bacterial resistance to antimicrobials can include (select all that apply) bacterial chromosomal mutations. prevention of drug entry into the cell.modification of target structure removal of drug from cell by efflux synthesis of enzymes that alter drug structure.

bacterial chromosomal mutations. prevention of drug entry into the cell.modification of target structure removal of drug from cell by efflux synthesis of enzymes that alter drug structure.

Binding of an activator protein to an upstream region of the promoter enhances transcription by which of the following? repression of the system increased binding of the ribosome to mRNA feedback inhibition bending of DNA to allow contact between RNA polymerase and the activator

bending of DNA to allow contact between RNA polymerase and the activator

Riboswitches __________. bind specific molecules and alter mRNA leader sequences. bind to ribosomes and stall translation induce transcription of proteins are RNA chaperone molecules, maintaining sRNA structure

bind specific molecules and alter mRNA leader sequences.

Virus-specified anti-sigma factors are used to __________. bind to the animal cell sigma factor, inactivating transcription inactivate viral genome replication by binding to unique envelope receptors bind to the host cell sigma factor, inactivating transcription inactivate viral replication in plants by binding to host-specific polymerases

bind to the host cell sigma factor, inactivating transcription

Expression of a structural gene is controlled by __________. the specific transcription of its mRNA binding of specific proteins to DNA sequences in its upstream region small regulatory RNA molecules known as riboswitches the controlled translation of the protein it encodes

binding of specific proteins to DNA sequences in its upstream region

All of the following are true of biofilms EXCEPT that __________. biofilm formation and dispersal are regulated processes biofilms are composed of only one species at a time biofilms form on virtually all submerged surfaces in nature biofilms protect organisms from antibiotics

biofilms are composed of only one species at a time

quorum sensing is important in the regulation of which of the following bioluminescence. heat shock proteins. biofilm production. virulence. antibiotic production.

bioluminescence. biofilm production. virulence. antibiotic production.

Which of the following activities is a result of cyclic di-guanosine monophosphate synthesis? Select all that apply. synthesis of flagella biosynthesis of extracellular matrix during biofilm formation reduction in activity of flagellar motor transition from sessile to planktonic growth during biofilm dispersal transition from planktonic to sessile growth during biofilm formation

biosynthesis of extracellular matrix during biofilm formation reduction in activity of flagellar motor transition from planktonic to sessile growth during biofilm formation

A mutation in the genome of an organism can affect __________. the wild-type strain both the genotype and phenotype of the organism the organism's genotype alone the organism's phenotype alone

both the genotype and phenotype of the organism

Normal PrPC is converted into infectious pathogenic PrPSc _________. by PrPSc that binds to the normal protein and causes it to become misfolded as a result of a mutation in the normal gene. by a virus that binds to the normal protein and causes it to become misfolded by interaction of PrPC from one species with that of a second species by an enzyme that cleaves off parts of the normal protein

by PrPSc that binds to the normal protein and causes it to become misfolded

Which protein accumulates when phage lambda infects a bacterial cell and leads to the activation of the lysogenic pathway? lysogen cro cII cI

cI

A nucleotide-altering chemical can cause double-stranded breaks in the DNA.can slip in between stacked bases, causing bulges in the DNA structure. can alter nitrogenous bases of DNA, resulting in incorrect base pairing. can be incorporated into the DNA, to cause a mispairing of bases. can generate free radicals, resulting in double-stranded breaks in the DNA.

can alter nitrogenous bases of DNA, resulting in incorrect base pairing.

CheY-P

can bind to the flagellum in order to allow tumbles to occur.

response regulator protein

can reset receptors so that they respond to a chemical again

The protein shell surrounding the genome of a virus is called a(n) __________. icosahedron capsid capsomere cylinder

capsid

A system that is used in bacteria to control the regulation of several operons that encode enzymes that metabolize different carbon sources is called __________. catabolite repression induction positive control repression

catabolite repression

frameshift mutation

caused by the addition or deletion of one or more base pairs. These changes cause a shift in the reading frame for protein synthesis.

positive control

certain genes are only expressed in the presence of a controlling factor. This factor will help RNA polymerase bind tightly to the promoter region for that gene.

tumbles

change the cell's orientation to a random direction

Regulation of chemotaxis requires that organisms such as P. aeruginosa respond to chemicals in the environment. What types of signals do these organisms sense and use as a basis for response? Select the best answer. spatial gradients of a chemical the absolute concentration of a chemical changes in concentration of a chemical over time both temporal and spatial changes in chemical concentration

changes in concentration of a chemical over time

base analogs

chemicals that resemble bases and can be accidentally incorporated into DNA instead of the correct bases.

In the bacterial world, a gene located on which of the following would be the LEAST likely to be transferred? chromosome a resistance plasmid the phage Mu an F plasmid

chromosome

Bacterial cells that can naturally take up DNA from the environment are known as __________. mutant deformed transformed competent

competent

The process by which wild-type function is restored to a mutant strain by creating a merodiploid is known as __________. complementation conjugation transduction reversion

complementation

A mutation in the gene encoding the lactose repressor (lacI) that prevents lactose from binding to the LacI protein would result in constant expression of the lac operon in the absence of lactose. constant expression of the lac operon in the presence of lactose. constant repression of the lac operon in the absence of lactose. constant repression of the lac operon in the presence of lactose.

constant repression of the lac operon in the presence of lactose.

CheA-P

contributes a phosphate to CheY

Mechanisms for controlling enzyme activity include which of the following? Select all that apply. addition of short sections of new amino acid sequence. covalent modification of the enzyme. degradation of the enzyme. phosphorylation feedback inhibition.

covalent modification of the enzyme. degradation of the enzyme. phosphorylation feedback inhibition.

CheY

determines the direction of movement of the flagellum.

Bacteriophage genomes are typically composed of

double-stranded DNA

When describing the bacteriophage genome, which terms could be used? Select all that apply. ds RNA ss DNA ds DNA ss RNA

ds RNA ss DNA ds DNA ss RNA

What genome composition makes viruses most susceptible to destruction by prokaryotic restriction endonucleases? all of these genomes are equally susceptible ssDNA dsRNA dsDNA all DNA genomes are equally susceptible

dsDNA

In temperate phages such as lambda, the virus __________. modifies the host RNA polymerase establishes a stable relationship with the host cell and does not destroy it replicates and then bursts from the host cell attaches to the outside of the host cell but does not enter it

establishes a stable relationship with the host cell and does not destroy it

Initial attachment of bacteria to a surface often involves ______. exopolymers and is reversible either flagella or exopolymers and is irreversible flagella and is irreversible flagella and is reversible exopolymers and is irreversible

flagella and is reversible

horizontal gene transfer

gene transfer between mature organisms or viruses

When multiple unrelated genes are regulated simultaneously in response to a change in the environment, this is known as __________. operon control of gene expression feedback inhibition global control of gene expression local control of gene expression

global control of gene expression

Quorum sensing is important in the regulation of all the following EXCEPT bioluminescence. heat shock proteins. biofilm production. virulence. antibiotic production.

heat shock proteins

Which of the following is an example of a global control mechanism of gene expression? tryptophan operon maltose operon lac operon heat shock response

heat shock response

What type of symmetry does the tobacco mosaic virus exhibit? bilateral symmetry icosahedral symmetry helical symmetry radial symmetry

helical symmetry

The lac operon in E. coli is repressed by a DNA-binding protein. Which of the following structures interacts with the sugar-phosphate backbone and the nitrogenous bases? stabilization helix zinc finger leucine zipper helix-turn-helix

helix-turn-helix

Bacteriophage gene expression uses __________. host and virally encoded proteins bacterial proteins only host cell-encoded proteins only virally encoded proteins only

host and virally encoded proteins

If autophosphorylation of CheA protein does NOT occur, then E. coli cells must be tumbling. in a gradient of a repellant. in a gradient of a chemoattractant. rotating flagella clockwise and tumbling rotating flagella clockwise.

in a gradient of a chemoattractant.

Which of the following contribute to the increased tolerance or resistance of biofilm bacteria to antimicrobials? Select all that apply. increased drug efflux dormancy facilitation of horizontal gene transfer inactivation of antimicrobials by binding

increased drug efflux dormancy facilitation of horizontal gene transfer inactivation of antimicrobials by binding

The synthesis of β-galactosidase is regulated by __________. induction induction and catabolite repression catabolite repression repression

induction and catabolite repression

temperate viruses

infect a cell and integrate into the genome of the host. Each time the cell replicates, the viral genome is replicated as well.

lytic viruses

infect a cell, replicate, assemble, and then lyse the cell to release new viral particles.

After infection and during the eclipse period, __________. viruses burst from the infected cell infectious viruses cannot be detected in the culture medium virus DNA is being reverse-transcribed infectious viruses are detected in the culture medium

infectious viruses cannot be detected in the culture medium

Initiation of biofilm formation in many organisms is at least in part regulated by c-di-GMP, which alters gene expression and enzyme activity leading to all of the following EXCEPT __________. initiation of extracellular polysaccharide production production of intercellular signaling molecules formation of cell surface attachment proteins initiation of flagella formation

initiation of flagella formation

Transposons are used in research to create random mutations in an organism's genome. Transposons create mutations by __________. deleting a gene inserting into a gene creating a gene duplication creating a point mutation

inserting into a gene

The methyl-accepting chemotaxis proteins of bacteria integrate multiple signals through a two component phospho-relay system. are directly connected to the flagellar motor to guide the bacterium. can only sense conditions that are favorable for bacterial growth. tell the bacterium which way to go.are sensor kinases

integrate multiple signals through a two component phospho-relay system.

Chemical mutagens, UV radiation, and ionizing radiation all increase mutation rates, but they have different mechanisms. Which type of mutagen would be best suited for creating frameshift mutations within a genome? base analogs alkylating agents intercalating agents UV radiation All of the choices are likely to create frameshift mutations.

intercalating agents

Chemical mutagens, UV radiation, and ionizing radiation all increase mutation rates, but they have different mechanisms. Which type of mutagen would be best suited for creating large deletions and rearrangements within a genome? UV radiation chemical mutagens ionizing radiation Chemical, UV, and ionizing radiation would create large deletions and rearrangements if used in a very high dose.

ionizing radiation

Integration of linear transforming DNA into the chromosome is not required for the expression for the transformed genes. is catalyzed by the RecA gene. almost never occurs because restriction endonuclease will degrade the DNA before it is integrated. only occurs in laboratory-based systems in artificial competent cells.

is catalyzed by the RecA gene.

How does 2-aminopurine cause mutations in DNA? inserts between two base pairs places a methyl group on guanine cross-links DNA strands is incorporated instead of adenine

is incorporated instead of adenine

What enzymes catalyze the same reaction but differ in amino acid sequence? ribozymes allosteric enzymes isoenzymes holoenzymes

isoenzymes

constitutive

it is always in the same state and cannot be regulated. In the case of gene expression, it means that the gene is always turned on.

Certain viruses are immune to host restriction systems. Which of the following viral genomes would be affected by this system? lambda, a dsDNA bacteriophage M13, a ssDNA bacteriophage MS2, a ssRNA bacteriophage φ6, a dsRNA bacteriophage

lambda, a dsDNA bacteriophage

The enzyme lysozyme is used to __________. make a hole in the bacterial cell wall for release of the mature virus particles replicate viral RNA so that transcription occurs at relevant time points form a scaffold so that mature viral particles can be assembled attach to the cell wall of the bacterium so that entry may occur

make a hole in the bacterial cell wall for release of the mature virus particles

What phase begins as newly synthesized viral nucleic acid molecules are packaged into their protein capsids? release phase eclipse phase maturation phase latent phase

maturation phase

How is the activity of a riboswitch controlled? repressor binding can change its structureby other riboswitches small RNA complementary binding disrupts its function sigma factor binding alters its structure metabolite binding can change its structure

metabolite binding can change its structure

There are several different types of mutations possible in the base sequence of DNA. If a GGC (glycine) codon were changed to UGC (cysteine), it would be termed a __________. wild type silent mutation missense mutation nonsense mutation

missense mutation

A strategy used by T4 bacteriophage to control transcription by host cell RNA polymerase is __________. modification of RNA polymerase to recognize only virus-encoded promoters denaturation of host RNA polymerase modification of the promoter regions of host cell genes degradation of host cell polymerase modification of the internal cell environment

modification of RNA polymerase to recognize only virus-encoded promoters

Protein activity can be regulated by

modifying the protein. For example, enzyme activity can be regulated by the binding of allosteric molecules.

Bacteriophage have a ________ complex structure than animal viruses, because ________. less / their prokaryotic cells have a simple structure compared to eukaryotic cells less / the bacteriophage does not have to penetrate the nucleus more / the bacteriophage must penetrate the peptidoglycan cell wall more / bacteriophages must be coated by lipopolysaccharide to attach to bacterial cells

more / the bacteriophage must penetrate the peptidoglycan cell wall

point mutations

most mutations. changes in a single base pair. They are given names based on the type of change they cause during translation.

chemotaxis

movement towards a chemical (positive chemotaxis) or away from a chemical (negative chemotaxis).

5-Bromouracil and nitrous acid are __________. teratogens carcinogens mutagens flammable

mutagens

The addition of two bases to the genome of a prokaryote would be most damaging if located __________. at the very end of the coding region of a protein near the beginning of the coding region of a protein anywhere within the coding region of a protein in the middle of the coding region of a protein

near the beginning of the coding region of a protein

nonsense mutation

occurs when a sense codon (that codes for a protein) is changed to a nonsense codon (a stop codon).

single base substitution

occurs when one base is substituted for another (e.g., if an adenine is substituted for a thymine).

A cluster of genes arranged in a linear, consecutive manner that is under the control of a single operator is called __________. regulon genome gene cluster operon

operon

Lysozymes and penicillin both disrupt the bacterial cell wall peptidoglycan, leading to cell lysis. However, their mechanisms of action are different, resulting in the fact that __________. penicillin kills only growing bacterial cells penicillin cleaves the glycosidic bonds in the peptidoglycan backbone lysozyme cleaves the peptide cross-links in peptidoglycan. penicillin kills both bacterial and eukaryotic cells

penicillin kills only growing bacterial cells

Bacteria can survive the presence of antibiotics through a variety of mechanisms. Which of the following would NOT be a genetically inherited form of antibiotic resistance? persistence modification of the antibiotic target enzymatic inactivation of the antibiotic efflux pumping

persistence

Cyclic dimeric guanosine monophosphate (c-di-GMP) serves as a messenger molecule in bacterial cells to coordinate a shift from ________ to ________ growth. planktonic / sessile sessile / planktonic stationary / exponential monomorphic / polymorphic

planktonic / sessile

Which regulatory mechanisms depend on a conformational change in protein/enzyme structure to change activity? attenuation positive control negative control feedback inhibition catabolite repression

positive control negative control feedback inhibition catabolite repression

Chemotaxis by Pseudomonas aeruginosa requires regulation of macromolecules in response to signals. Protein regulation is very important and can be grouped into two categories: those that are based on protein activity and those that are based on the amount of protein present. Based on the information in the chapter, select the type of regulation described that does NOT affect the amount of protein present. Select the best answer. .small RNA (sRNA) regulation regulating amount of mRNA made regulation of transcription post-translational modification controlling whether mRNA is translated attenuation catabolite repression

post-translational modification

late viral proteins

produced later, when virus assembly begins. virion structural components proteins produced in large amounts capsid components

Viral proteins are categorized as early, middle, and late. Early proteins typically are necessary for copying the viral genome. production of viral mRNA and copying the viral genome. packaging of DNA into the nucleocapsid. production of viral mRNA.

production of viral mRNA and copying the viral genome.

prions

protein infectious units. They cause disease in mammals. The prion builds up and causes brain and nervous tissue destruction.

early viral proteins

proteins that are produced most rapidly after viral infection begins. These are proteins, including enzymes, that are needed for the virus to begin its life cycle. proteins that interfere with host genome expression RNA polymerase RNA replicase proteins produced in small amounts DNA polymerase

The plaque assay is a method for __________. quantifying bacteria quantifying algae quantifying viruses quantifying Archaea

quantifying viruses

Molecular chaperones function to _______. Select all that apply. recognize unfolded or partially denatured proteins fold newly formed proteins to their proper shape provide ATP to proteins that require it prevent incorrect folding of proteins guide normal, functional proteins to their cellular location

recognize unfolded or partially denatured proteins fold newly formed proteins to their proper shape prevent incorrect folding of proteins

To be retained permanently in the bacterial chromosome, a piece of DNA that has been transferred into the cell must __________. recombine into the chromosome replicate in the cytoplasm be taken up by a virus be degraded by restriction enzymes

recombine into the chromosome

When DNA is transferred into a prokaryotic cell it may (Select all that apply) recombine with the host chromosome. be degraded by enzymes. replicate independent of the host chromosome. remain in the cytoplasm, unable to replicate.

recombine with the host chromosome. be degraded by enzymes. replicate independent of the host chromosome. remain in the cytoplasm, unable to replicate.

Regulatory proteins regulate transcription. bind to specific DNA sites.are influenced by small molecules. regulate transcription, bind specific DNA sites, and can be influenced by small molecules.

regulate transcription, bind specific DNA sites, and can be influenced by small molecules.

Considering the catabolite repression mechanism, which observation would make you suspect it is occurring? RNA polymerase bound to biosynthetic promoter sequences CRP bound to operator sites elevated levels of transcripts for maltose and sucrose catabolism relatively low intracellular cyclic-di-GMP levels relatively low intracellular cyclic AMP levels

relatively low intracellular cyclic AMP levels

When exponentially growing cells are grown in a medium containing arginine, the transcription of the arginine biosynthetic enzymes is stopped. This is called __________. repression enzyme degradation induction feedback inhibition

repression

virus

require host cells to synthesize new viral particles. They do not have the basic cellular machinery of living things. In order for an organism to be capable of expressing its own genome, it needs all of the components for gene expression. This includes DNA that can be transcribed to RNA and RNA that can be translated to proteins.

These RNA viruses replicate through a DNA intermediate. retroviruses lysogenic viruses enveloped viruses latent viruses

retroviruses

The Ames test is based on __________. recombination frequency of the wild-type strain mutation rates of wild-type strains reversion rates of an auxotroph frequency of lethal mutations

reversion rates of an auxotroph

Peptide bond formation is catalyzed by __________ and occurs between the __________ sites of the ribosome. ribosomal RNA (rRNA); A and P sites ribosomal RNA (rRNA); P and E sites ribosomal proteins; A and P sites ribosomal proteins; P and E sites

ribosomal RNA (rRNA); A and P sites

Which two antimicrobials affect bacterial nucleic acid synthesis? tetracycline and amphotericin B trimethoprim and sulfonamides tetracycline and bacitracin rifampin and quinolones penicillin and vancomycin

rifampin and quinolones

Which of the following is are mechanisms by which sRNA alters translation of their mRNA target? sRNA binding increases the stability of mRNA. sRNAs binding blocks the ribosome-binding site on the mRNA. sRNA binding increases the degradation of mRNA. sRNAs fold into specific three-dimensional structures found on the mRNA.

sRNA binding increases the stability of mRNA. sRNAs binding blocks the ribosome-binding site on the mRNA. sRNA binding increases the degradation of mRNA.

Which of the following is NOT a mechanism by which sRNA alters translation of their mRNA target? sRNA binding increases the stability of mRNA. sRNAs binding blocks the ribosome-binding site on the mRNA. sRNA binding increases the degradation of mRNA. sRNAs fold into specific three-dimensional structures found on the mRNA.

sRNAs fold into specific three-dimensional structures found on the mRNA.

The isolation of a single mutant from a population containing millions of wild-type cells is done by using __________. transformation mutagenesis screening selection

selection

The components of a typical two-component regulatory system are __________. activator and repressor sensor kinase and response regulator repressor and inducer RNA polymerase and activator

sensor kinase and response regulator

A base substitution that does NOT affect the amino acid in the protein is a __________. frameshift mutation nonsense mutation silent mutation missense mutation

silent mutation

Types of regulation that affect the amount of protein present small RNA (sRNA) regulation regulating amount of mRNA made regulation of transcription post-translational modification controlling whether mRNA is translated attenuation catabolite repression

small RNA (sRNA) regulation regulating amount of mRNA made regulation of transcription controlling whether mRNA is translated attenuation catabolite repression

In E.coli, during the heat shock response, Hsp70 functions to __________. stabilize newly synthesized proteins degrade newly synthesized proteins unfold newly synthesized proteins degrade old cellular proteins

stabilize newly synthesized proteins

Type V secretion systems are used by pathogens to secrete virulence factors from the cytoplasm, across both the plasma membrane and outer membrane, and into host cells. start with Sec-dependent transport across the plasma membrane, but the transported protein then forms a channel in the outer membrane through which it autotransports. can transport DNA during conjugation, in addition to proteins. move proteins from the cytoplasm across both the plasma membrane and the outer membrane.

start with Sec-dependent transport across the plasma membrane, but the transported protein then forms a channel in the outer membrane through which it autotransports.

Which of the following are global regulatory systems? stringent response. heat shock response. stationary phase. catabolite repression. amino acid synthesis.

stringent response. heat shock response. stationary phase. catabolite repression.

Viruses that can infect their host and establish a stable, long-term relationship are known as __________. naked lytic temperate enveloped

temperate

The presence of the F plasmid in a cell alters all the following properties of a cell EXCEPT __________. .the ability to mobilize DNA for transfer the ability to create Hfr strains the ability to generate a pilus the ability to replicate DNA alteration of cell surface receptors so the cell cannot act as a recipient in conjugation.

the ability to replicate DNA

The presence of the F plasmid in a cell alters all the following properties of a cell EXCEPT __________. the ability to replicate DNA the ability to create Hfr strains the ability to mobilize DNA for transfer the ability to generate a pilus

the ability to replicate DNA

CheW

the coupling protein that associates with MCP.

A unique feature that is characteristic of retroviruses is __________. RNA in the capsid a capsid with head, tail, and tail fibers both DNA and RNA in the genome the enzyme reverse transcriptase

the enzyme reverse transcriptase

adaptation

the gradual reduction in response to a chemical when exposure is constant over time.

Which of the following choices can indicate horizontal gene transfer? the presence of genes that encode proteins typically found only in distantly related species the location of genes in different operons than found in closely related bacteria the presence of regulatory gene segments the presence of gene duplications

the presence of genes that encode proteins typically found only in distantly related species

catabolite

the product of a catabolic reaction (i.e., a reaction that breaks a molecule down).

You are studying a protein in Salmonella typhimurium that you believe is a toxin. Whenever you attempt to purify the protein from lysed cell cultures, you get two forms of the protein. One form is smaller than the other and is missing 15 amino acids from the N-terminus compared to the larger form. This leads you to hypothesize that there are two termination sites in the mRNA. you need to re-do the experiment because there should only be one form. the protein requires chaperonins to fold properly. the protein is secreted and folds outside of the cell.

the protein is secreted and folds outside of the cell.

The first step of translation begins when __________. the ribosome binding site (RBS) on the mRNA binds to the 23S rRNA tRNA binds to the P site on the ribosome to initiate translation the initiator aminoacyl-tRNA binds to the start codon on the mRNA at the A site of the ribosome the 30S ribosomal subunit combines with the 50S ribosomal subunit, enclosing the mRNA the ribosome binding site (RBS) on the mRNA binds to the 16S rRNA

the ribosome binding site (RBS) on the mRNA binds to the 16S rRNA

CheA

the sensor kinase that associates with MCP; undergoes autophosphorylation at a higher rate when the attractant concentration decreases.

The promoters of positively controlled operons require activator proteins because they are needed to bind to the allosteric site of RNA polymerase. they are required to inactivate the repressor proteins. RNA polymerase easily recognizes the consensus sequence. they have nucleotide sequences which are not close matches to the consensus sequence and thus bind RNA polymerase weakly,

they have nucleotide sequences which are not close matches to the consensus sequence and thus bind RNA polymerase weakly,

Attenuation is a type of regulation that directly controls transcriptional activity. both transcriptional and translational activity. allosteric enzyme activity. post-translational activity translational activity.

transcriptional activity.

Referring to attenuation in the regulation of the tryptophan operon, when there are high levels of tryptophan available to the organism, ____. the tryptophan operon is being transcribed at relatively high levels tryptophan inactivates the repressor protein transcriptional termination is likely when ribosomes stall at a tryptophan codon transcriptional termination is likely when ribosomes pause at the end of the leader peptide amino acids will bind to the tryptophan riboswitch and turn it off

transcriptional termination is likely when ribosomes pause at the end of the leader peptide

Currently, the best defined method for transferring DNA into certain archaeal cells is __________. transformation transposition conjugation transduction

transformation

The uptake of free DNA from the environment is ________, while transfer of DNA with cell-to-cell contact would most likely result in ________. transduction / conjugation transformation / conjugation transformation / transduction conjugation / transformation

transformation / conjugation

Most riboswitches control

translation

β-lactam antibiotics inhibit peptidoglycan transpeptidation. transglycosylation. autolysins. transglycosylation and transpeptidation. glycan tetrapeptide precursor formation.

transpeptidation.

The enzyme required to carry out transposition is known as __________. transposase resolvase reverse transcriptase integrase

transposase

Most mobile DNA elements are __________. F plasmids transposons viruses viroids

transposons

Which of the following is the correct abbreviation for a mutation in a gene that synthesizes one of the enzymes involved in tryptophan production? trpC1 (in italics) Trp- TrpC (in italics) trp

trpC1 (in italics)

The amount of protein present can be regulated by

turning on and off the processes that produce proteins

The levels of porin proteins OmpC and OmpF are controlled in E. coli. If the osmotic pressure is low, OmpF expression increases. If the osmotic pressure is high, OmpC expression increases. What kind of regulation is this an example of? global control catabolite repression two-component regulatory system quorum sensing

two-component regulatory system

You are examining an enzyme associated with cysteine biosynthesis. You would expect expression of this enzyme to be induced by cysteine. under negative control by induction. under positive control. under positive control by induction. under negative control by repression

under negative control by repression

quorum sensing

used by many cells to trigger transcription of specific genes, only when large numbers of cells are present. If a single cell produces light for bioluminescence, there will be a very small amount of light produced, wasting energy. If millions of cells produce light at the same time, there will be a large production of bioluminescence and be worthwhile.

two-component system

uses two parts. In signal transduction, this often includes a part in the membrane and a part in the cytoplasm.

What type of regulation is used by Pseudomonas aeruginosa for the type of chemotaxis described in the introductory passage? Select the best answer. using a one-component system to inhibit enzymes that restrict flagellar movement by regulating the transcription of mRNA used to produce enzymes by regulating the production of proteins used in flagella synthesis using a two-component system using a two-component system to regulate the activity of existing proteins

using a two-component system to regulate the activity of existing proteins

The SOS system repairs DNA that has gaps, breaks, and other lesions by cutting DNA from other parts of the genome and pasting it into the gaps or damaged areas. using specialized DNA polymerases that will synthesize a new DNA strand even if there is not a normal complementary DNA strand to act as a template. stabilizing single-stranded DNA until the next round of normal replication. using available mRNA and a special RNA-dependent DNA polymerase to fill in the gaps and replace damaged DNA.

using specialized DNA polymerases that will synthesize a new DNA strand even if there is not a normal complementary DNA strand to act as a template.

A virus in its extracellular state is known as a __________. bacteriophage capsid virus virion

virion

temperate bacteriophages

viruses that are capable of a lysogenic life cycle, while virulent bacteriophages use only the lytic cycle

When does attenuation of the tryptophan operon occur? when the transcription for the tryptophan biosynthetic enzymes has been terminated when the tryptophan leader peptide has been synthesized when numerous charged tryptophan tRNAs exist when the tryptophan operon has been fully transcribed

when the transcription for the tryptophan biosynthetic enzymes has been terminated when the tryptophan leader peptide has been synthesized when numerous charged tryptophan tRNAs exist

When does attenuation of the tryptophan operon NOT occur? when the transcription for the tryptophan biosynthetic enzymes has been terminated when the tryptophan leader peptide has been synthesized when numerous charged tryptophan tRNAs exist when the tryptophan operon has been fully transcribed

when the tryptophan operon has been fully transcribed