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Biology & Life Science
Q:
An RNA genome itself serves as mRNA in negative-stranded RNA viruses.
Q:
A lytic infection results in death of the host cell.
Q:
The virus repressor protein provides immunity to infection by the same type of virus.
Q:
A temperate virus does not exist as a virus particle inside the host cell.
Q:
Lysogeny is unique to bacteriophages; similar relationships have not been found among the animal viruses.
Q:
Temperate viruses can enter into either a lytic or lysogenic cycle.
Q:
Although T4 encodes over 250 proteins, it does not encode its own RNA polymerase.
Q:
Tailed bacterial viruses can be used as genetic engineering tools.
Q:
RNA viruses encode host restriction systems designed to destroy host DNA.
Q:
Penetration requires that the entire virus is inserted within the host.
Q:
In the first few minutes after host cell infection, the virus undergoes an eclipse.
Q:
Some viruses possess icosahedral heads and helical tails.
Q:
There is at least one known virus whose genome is actually larger than a cellular genome.
Q:
Most of the genetic diversity on earth resides in viral genomes.
Q:
Viruses can redirect host metabolic functions.
Q:
Viruses have both an intracellular and an extracellular form.
Q:
Viruses can confer additional properties on their host cells, which can in turn be inherited.
Q:
The growth of viruses in a culture is described as a one-step growth curve, because
A) virion numbers show no increase during intracellular replication and can only be counted after the virions burst from the host cell.
B) there is only one step in the viral life cycle which leads to only one replicative cycle in a culture.
C) assembly and release actually occur in one step.
D) the eclipse phase prevents the plating and enumeration of virions although new virions are produced at a steady rate during the eclipse phase.
Q:
The concentration of infectious plaque forming units (pfu) per volume of fluid is known as the
A) infectivity.
B) virulence.
C) titer.
D) fluid infectivity.
Q:
In viruses, genetic information flows from ________ to ________.
A) RNA / virion
B) nucleic acid / protein
C) capsid / virion
D) DNA / protein
Q:
What are the consequences of a viral infection of an animal cell?
A) rapid lysis or latent infections
B) lysogeny followed by eventual lysis
C) lysis or lysogeny
D) Outcomes vary from rapid lysis to persistent infections, latent infections, or cancer.
Q:
For bacteriophages and animal viruses ________ is the step in the viral life cycle that determines host cell or tissue specificity.
A) attachment
B) penetration
C) synthesis
D) assembly
Q:
You isolate a purify a bacteriophage that can replicate in E. coli. Through chemical analyses you determine that the only nucleic acid present is RNA. You isolate the RNA and put it in a test tube with all of the necessary proteins and RNAs for translation. The RNA is translated and new infectious virions are made. What does this tell you about the bacteriophage?
A) The RNA genome is of the plus sense.
B) The RNA genome is of the plus sense and RNA replicase is present in the viral capsid.
C) The new bacteriophage is a retrovirus.
D) RNA replicase is present in the viral capsid.
Q:
Whether lambda phage undergoes the lytic or lysogenic cycle is dependent on the accumulation of
A) Cro protein.
B) viral genomes.
C) cI protein.
D) methylated DNA.
Q:
What would be the consequence of deleting the late T4 genes?
A) The T4 genome would not be copied.
B) T4 mRNA would not be produced.
C) T4 capsid proteins would not be made.
D) ATP would not be produced and the T4 genome would not be packaged into the capsid.
Q:
How do bacteriophage influence bacterial evolution?
A) Bacteriophage cause cleavage and rearrangement of bacterial genomes, thus accelerating bacterial evolution.
B) Bacteriophage lyse mutated bacterial cells, thus preventing them from replicating and passing on their genetic information.
C) Bacteriophage transfer genetic information between bacterial cells through transduction, thus increasing the genetic diversity of bacterial populations.
D) Bacteriophage decrease the size of bacterial populations and thus decreasing genetic diversity and slowing down bacterial evolution.
Q:
In a natural population of diverse slow-growing prokaryotic cells, what type of viruses would you expect to be most common?
A) lytic bacteriophages
B) enveloped viruses
C) icosahedral viruses
D) temperate bacteriophages
Q:
A cell that allows the complete replication cycle of a virus to take place is said to be a
A) permissive host.
B) viral cell.
C) dead cell.
D) lytic cell.
Q:
Viral proteins are categorized as early, middle, and late. Early proteins typically are necessary for
A) production of viral mRNA.
B) packaging of DNA into the nucleocapsid.
C) copying the viral genome.
D) production of viral mRNA and copying the viral genome.
Q:
Which of the following samples would contain the MOST genetic diversity?
A) viral metagenomes from the ocean
B) bacterial metagenomes from the ocean
C) microbial eukaryotic metagenomes from the ocean
D) viral metagenomes from human red blood cells
Q:
In E. coli, the adenine in the sequence GATC is methylated by the Dam enzyme. In the same cells a restriction endonuclease recognizes and cleaves dsDNA with GATC on either strand. Why does E. coli have these two enzymes?
A) The enzymes cut the E. coli genome into pieces that bind to viral particles and inhibit viral replication.
B) The enzymes increase the rate of mutation and genome rearrangement, thus increasing the likelihood that E. coli cells will mutate and become resistant to viral infection.
C) The enzymes encourage lysogeny because the cleavage sites are recognized by viral integrases.
D) The enzymes protect E. coli from infection by preferentially degrading viral or other exogenous DNA that is not methylated.
Q:
The T4 phage protects its DNA from host restriction endonucleases by
A) glucosylating cytosine bases in the T4 genome to prevent DNA cleavage.
B) methylating all four bases (A, T, C, G) in the T4 genome to prevent DNA cleavage.
C) integrating the viral genome into the host genome where it will not be degraded.
D) circularizing the viral genome so that it will not be degraded.
Q:
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?
A) Early T4 genes encode for 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.
B) Early and middle T4 genes encode for proteins that modify the activity of sigma factors and host RNA polymerase to regulate the expression of T4 genes.
C) 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.
D) Rolling circle replication of the viral genome ensures that the genes are available for transcription in the correct order.
Q:
When solutions of host cells and infectious virions are mixed and spread on an agar plate, ________ form where viruses lyse the host cells.
A) insertion sequences
B) plaques
C) prophages
D) colonies
Q:
The use of ________ is the easiest and most effective way of studying many animal and plant viruses.
A) bacterial cultures
B) tissue or cell culture
C) live hosts
D) prophages
Q:
Virions infecting some bacteria possess the enzyme ________ that makes a small hole in the bacterial cell wall, allowing the viral nucleic acid to enter.
A) peptidoglycanase
B) infectase
C) lysozyme
D) nuclease
Q:
Regarding the viral membrane of an enveloped virus, the lipids are derived from the ________, and the proteins are encoded by ________.
A) host's cell membrane / viral genes
B) virion / viral genes
C) host's cell membrane / host's genes
D) virion / host's genes
Q:
You are attempting to mutate lambda to affect whether lysis or lysogeny occurs after lambda infection. Which mutation would INCREASE the chances of LYSOGENY over lysis?
A) deletion or inactivation of the cI gene
B) deletion or inactivation of the cro gene
C) overexpression of the cro gene
D) deletion of both the cro and cI genes
Q:
The size and shape of viral particles is largely governed by the size and packaging of the viral
A) envelope.
B) enzymes.
C) prophage.
D) genome.
Q:
The term "phage" is generally reserved for the viruses that infect
A) animals.
B) plants.
C) bacteria.
D) multiple species.
Q:
When a virus enters a host cell in which it can replicate, the process is called a(n)
A) insertion.
B) infection.
C) prophage.
D) excision.
Q:
What genome composition makes viruses most susceptible to destruction by prokaryotic restriction endonucleases?
A) dsDNA
B) ssDNA
C) dsRNA
D) ssRNA
Q:
Bacteriophage have a ________ complex structure than animal viruses, because ________.
A) more / bacteriophages must be coated by lipopolysaccharide to attach to bacterial cells
B) less / the bacteriophage does not have to penetrate the nucleus
C) more / the bacteriophage must penetrate the peptidoglycan cell wall
D) less / there prokaryotic cells have a simple structure compared to eukaryotic cells
Q:
Which of the following are the hosts for most enveloped viruses?
A) Bacteria
B) animals
C) Archaea
D) fungi
Q:
When packaged in the virion, the complete complex of nucleic acid and protein is known as the virus
A) capsid.
B) concatemer.
C) nucleocapsid.
D) envelope.
Q:
The consequence of an infection by a temperate bacteriophage is that the bacterial cell
A) lyses before it gets a chance to divide.
B) never lyses but continues to divide and replicate both the virus and the cell.
C) divides faster at moderate temperatures.
D) may lyse before it divides or may continue to divide and replicate both the virus and the cell.
Q:
Rolling circle replication of the lambda genome differs from replication of a bacterial chromosome in that
A) bidirectional replication forks are not formed.
B) only a single strand of the genome is copied.
C) no concatamers are formed.
D) only a single strand of the genome is copied and no concatamers are formed.
Q:
The primer for retrovirus reverse transcription is a specific
A) tRNA encoded by the cell.
B) tRNA encoded by the virus.
C) nuclear tRNA.
D) nuclear tDNA.
Q:
Retroviruses are medically important viruses because
A) they include the viruses the cause hepatitis.
B) some retroviruses cause cancer.
C) they include the virus that causes AIDS.
D) they include viruses that cause cancer and AIDS.
Q:
Which of the following statements is TRUE?
A) Lambda is a temperate phage that infects Escherichia coli.
B) Lambda is a linear double-stranded DNA phage.
C) Lambda is replicated by the rolling circle mechanism.
D) Lambda is a temperate phage that replicates its double-stranded DNA genome with a rolling circle mechanism.
Q:
The virus repressor protein
A) controls the prophage's lytic genes but not the incoming genomes of the same virus.
B) does not control the prophage's lytic genes but does control the incoming genomes of the same virus.
C) controls both the lytic genes on the prophage and prevents an incoming virus of the same type.
D) has different actions in different situations.
Q:
A prophage replicates
A) along with its host while the lytic genes are expressed.
B) along with its host while the lytic genes are not expressed.
C) independently of its host while the lytic genes are expressed.
D) independently of its host while the lytic genes are not expressed.
Q:
The packaging mechanism of T4 DNA involves cutting of DNA from
A) linear genetic elements.
B) circular genetic elements.
C) DNA concatemers.
D) its host cells.
Q:
Which of the following enzymes would you expect to find in the virion of a retrovirus, but NOT in a bacteriophage?
A) lysozyme
B) methylase
C) restriction enzymes
D) reverse transcriptase
Q:
A virus that kills its host is said to be
A) lytic or virulent.
B) temperate.
C) lysogenic.
D) virulent or lysogenic, but not temperate.
Q:
Bacteriophages' genomes are typically composed of
A) single-stranded RNA.
B) single-stranded DNA.
C) double-stranded RNA.
D) double-stranded DNA.
Q:
Based on your knowledge of cellular and viral processes, which of the following would be (an) appropriate target(s) for antiviral drugs?
A) integrases
B) aminoacyl-tRNA synthetases
C) ribosomes
D) aminoacyl-tRNA synthetases and ribosomes
Q:
The discovery of retroviruses changed our understanding of
A) gene structure and organization.
B) the flow of genetic information.
C) protein synthesis.
D) infectious particles.
Q:
Restriction is
A) the viral process whereby a host's DNA ceases normal functioning.
B) the viral process whereby the virus prevents other viruses from entering the cell.
C) a general host mechanism to prevent the invasion of foreign nucleic acid.
D) a general host mechanism to prevent virus particles from further infective action.
Q:
Cellular receptors may be composed of
A) proteins.
B) carbohydrates.
C) lipids.
D) combinations of proteins, carbohydrates, and/or lipids.
Q:
ALL viral particles
A) are metabolically inert.
B) are smaller than bacterial cells.
C) contain an envelope to prevent its degradation outside of a host.
D) exhibit cell lysis under a particular condition.
Q:
Viruses infecting ________ are typically the easiest to grow in the laboratory.
A) plants
B) animals
C) fungi
D) prokaryotes
Q:
Reverse transcriptase is a(n)
A) RNA-dependent DNA polymerase.
B) DNA-dependent DNA polymerase.
C) RNA-dependent RNA polymerase.
D) DNA-dependent RNA polymerase.
Q:
Which statement is TRUE?
A) All viruses contain their own nucleic acid polymerases.
B) Many viruses contain their own nucleic acid polymerases.
C) Viruses do not contain their own nucleic acid polymerases.
D) The origins of the nucleic acid polymerases used by viruses are eukaryotic.
Q:
Enveloped viral membranes are generally ________ with associated virus-specific ________.
A) lipid bilayers / phospholipids
B) protein bilayers / lipids
C) lipid bilayers / glycoproteins
D) glycolipid bilayers / phospholipids
Q:
Viral size is generally measured in
A) micrometers.
B) picometers.
C) nanometers.
D) centimeters.
Q:
Viral replication occurs
A) intracellularly.
B) extracellularly.
C) both intracellularly and extracellularly.
D) either intracellularly or extracellularly, depending on the virus involved.
Q:
Viral replication is
A) independent of the host cell's DNA but dependent on the host cell's enzymes and metabolism.
B) independent of both the host cell's DNA and the host cell's enzymes and metabolism.
C) dependent on the host cell's DNA and RNA.
D) dependent on the host cell's DNA, RNA, enzymes, and metabolism.
Q:
Transcriptional regulators bind most frequently at the ________ site of DNA.
A) major groove
B) minor groove
C) histone complex
D) primary supercoil
Q:
A protein region with a specific function and structure is called a
A) conserved site.
B) domain.
C) locale.
D) motif.
Q:
Regulatory proteins
A) are influenced by small molecules.
B) bind to specific DNA sites.
C) regulate transcription.
D) regulate transcription, bind specific DNA sites, and can be influenced by small molecules.
Q:
When arginine is added to a culture growing exponentially in a medium without arginine, what occurs?
A) All cellular growth ceases.
B) Growth continues, but the production of enzymes required for the synthesis of arginine ceases.
C) Growth continues, but the production of enzymes required for the synthesis of arginine increases.
D) The cell returns to the lag stage of growth to synthesize the proteins necessary for the metabolism of arginine.
Q:
Regulation of an enzyme's activity occurs
A) transcriptionally.
B) translationally.
C) posttranslationally.
D) at any point on the enzymatic production pathway.
Q:
Provide evidence that supports the hypothesis that riboswitches are remnants of the RNA world when catalytic RNAs were the only self-replicating life forms.
Q:
Explain why cellular cannibalism is beneficial for sporulating Bacillus subtilis.
Q:
In considering the function of heat shock proteins, why is it not a surprise that these proteins are both highly conserved and very ancient? Provide your reasoning.
Q:
A cocktail of 30 compounds was identified to harbor a corepressor, and subsequent separation and purification was performed to test individual compounds. Describe an experiment that would enable you to identify the specific compound that acts as a corepressor for a catabolic pathway. Be certain to explain what will be measured and how you could conclude which compound is a corepressor.
Q:
Explain the function of cAMP in catabolite repression.
Q:
Contrast prokaryotic and eukaryotic regulation of gene expression.
Q:
How is transcription in Archaea controlled?