ch. 13 etext, pre/post, and end of chapter questions
Latent viruses are viruses that insert into the host cell's DNA. Which of the following viruses can be latent? HIV chicken pox virus herpesviruses all of the above
D
What are the template and end-product of the enzyme reverse transcriptase? A. Protein is the template and RNA is the end-product. B. RNA is the template and cDNA is the end-product. C. cDNA is the template and RNA is the end-product. D. RNA is the template and protein is the end-product.
B
What are viroids? A. Virus-like particles that cause disease in bacteria B. Short, naked stretches of RNA that do not code for proteins but cause disease in plants C. Virus-like particles that cause disease in humans D. Short, naked stretches of RNA that infect fungi
B
What is a continuous cell culture? A. A culture derived from normal haploid cells. B. A cell culture derived from tumor cells C. A culture derived from normal diploid cells D. A culture of viruses maintained in a laboratory indefinitely.
B
What type of organisms do phages infect? A. Plants B. Bacteria C. Animals D. Protozoa
B
Which of the following statements is false? Viruses may have circular DNA. dsRNA is found in bacteria more often than in viruses. Viral DNA may be linear. Typically, viruses have DNA or RNA but not both.
B
What is the term used to describe viral nucleic acid surrounded by a protein "shell"? A. Capsomere B. Capsid C. Icosahedron D. Nucleocapsid
D
Where does an enveloped virus get its envelope? A. From host proteins B. From the bacterial cell wall C. From the host immune system D. From a membrane of its host cell
D
Where does transcription occur in eukaryotic cells? A. In the lysosomes B. In the cytosol C. In the rough endoplasmic reticulum (rough ER) D. In the nucleus
D
Which characteristics are used to classify viruses? A. Type of nucleic acid alone B. Presence or absence of an envelope, shape, and size C. Shape, size, and staining characteristics D. Type of nucleic acid, presence or absence of an envelope, shape, and size
D
Which of the following is not a criterion for specific family classification of viruses? the type of nucleic acid envelope structure capsid type present lipid composition
D
Which part of animal viruses is involved in membrane fusion with a host cell? A. Glycoprotein spikes B. Viral nucleic acid C. Envelope D. The capsid
C
Why do viruses have to infect host cells? They infect host cells in order to steal the cell's genome. They infect host cells in order to cause tumors. They are dependent on host cell organelles and enzymes for their replication. They cannot survive outside a host cell.
C
How are lysogenic phages different from lytic phages? A. Lysogenic phages have dsDNA genomes, while lytic phages have ssRNA genomes. B. Lytic phages prevent reinfection of their host bacterium by the same type of phage, while lysogenic phages do not. C. Lytic phages can change the phenotype of a bacterium, while lysogenic phages do not. D. The genome of a lysogenic phage is integrated into its host genome.
D
How can viruses be distinguished from eukaryotic and prokaryotic organisms? A. Viruses may only be observed with a light microscope. B. Viruses contain more genetic material than eukaryotic and prokaryotic organisms. C. Unlike eukaryotes and prokaryotes, all viruses have RNA genomes. D. Viruses are acellular.
D
Negative-sense (-) ssRNA viruses require which of the following enzymes for their replication? reverse transcriptase DNA polymerase lysozyme RNA-dependent RNA transcriptase
D
A(n) ____________ is a membrane that surrounds some viral capsids.
ENVELOPE
According to the ICTV scheme of classification, viruses can be classified by a variety of characteristics, including the diseases they cause. True False
F
FILL IN THE GRAPH CYCLE
1-ATTACHMENT 2-ENTRY 3-SYNTHESIS 4-ASSEMBLY 5-RELEASE
Proviruses become a permanent part of the host cell's genome. True False
t
Name a structural difference between animal viruses and bacteriophages. A. Animal viruses may be enveloped; bacteriophages are always naked. B. The capsid of animal viruses enters the host cell, while those of bacteriophages stay outside the host cell. C. Animal viruses may have tails or tail fibers, while bacteriophages do not. D. Bacteriophages have glycoprotein spikes, while animal viruses do not.
A
List the steps of lytic phage replication in order. A. Entry, attachment, synthesis, assembly, and release B. Attachment, entry, synthesis, assembly, and release C. Synthesis, assembly, entry, attachment, and release D. Attachment, synthesis, entry, assembly, and release
B
A student is discussing viral terminology with her classmate, who is confused about the distinction between some of the terms. She explains that is another name for a complete virus. virion viroid prion capsid
A
Alcohol-based antiseptic hand solutions are more effective against enveloped viruses, such as flu viruses, than they are against naked viruses, such as cold viruses. This is true because a naked virus . has no membranous envelope has already injected its DNA or RNA into a host cell lacks capsomeres is one that is unattached to a host cell
A
Each of the following features is common to both bacteriophage and animal virus infections EXCEPT __________. uncoating attachment penetration assembly
A
HeLa cells are an example of a __________ cell culture. continuous viral diploid tumor
A
How do negative-sense single-stranded RNA (-ssRNA) viruses generate mRNA? A. They have an enzyme packaged in their capsids that transcribes -ssRNA into +ssRNA, which is used as mRNA and as a template for RNA replication. B. They use host cell enzymes to generate mRNA from their -ssRNA genome. C. Ribosomes facilitate transcription of -ssRNA. D. They first reverse transcribe their -ssRNA into DNA, then the DNA is transcribed into mRNA.
A
Which of the following is not an acellular agent? viroid virus rickettsia prion
C
Viruses are considered acellular, but what is one component viruses share with cells? presence of nucleic acid presence of cytosol presence of organelles presence of a cytoplasmic membrane
A
Viruses can be used to kill pathogenic bacteria such as Listeria. A virus that is specific for a bacterial host is called a . phage prion virion viroid
A
What effect does lysozyme have on bacteria? A. Lysozyme digests peptidoglycan, weakening their cell walls. B. Lysozyme inhibits bacterial DNA replication. C. Lysozyme punctures holes in bacterial cytoplasmic membranes. D. Lysozyme oxidizes bacterial cytoplasmic proteins.
A
What type of genome do viruses have? A. Depending on the virus, viral genomes can be either DNA or RNA, either of which can be single stranded or double stranded. B. A virus always has a single-stranded DNA (ssDNA) genome. C. Most cellular organisms have a genome consisting of double-stranded DNA (dsDNA), while viruses have a genome consisting of single-stranded RNA (ssRNA). D. Viruses have a double-stranded RNA (dsRNA) genome.
A
Which of the following terms refers to a virus in the extracellular state? virion bacteriophage capsid nucleocapsid
A
Which of the following types of virus replicates in the cell's nucleus? herpesvirus rotavirus HIV rabies virus
A
Which of the following viruses create a DNA intermediary molecule from the information in their RNA genomes? retroviruses negative-sense ssRNA viruses positive-sense ssRNA viruses dsDNA viruses
A
Which of the following viruses creates a DNA intermediary molecule from the information in its RNA genome? retroviruses negative-sense ssRNA viruses positive-sense ssRNA viruses dsDNA viruses
A
How can prions be destroyed? A. Heating to 482°C for four hours B. Rinsing with a 10% bleach solution C. Boiling for 2 hours D. Soaking in detergent solution for four hours
A Heating to 482°C for four hours or autoclaving at 132°C in concentrated sodium hydroxide for one hour deactivates prions.
NAME THESE
A-COMPLEX SHAPE OF MEGAVIRUS B-RABIES VIRUS COMPLEX C- HELICAL VIRUS D- POLYHEDRAL VIRIONS OF VIRUS
Compare and contrast a bacterium and a virus by writing either "Present" or "Absent" for each of the following structures. Structure Bacterium Virus Cell membrane Functional ribosome Cytoplasm Nucleic acid Nuclear membrane
ALL OF THESE PRESENT IN BACTRIUM EXCEPT FOR NUCLEAR MEMBRANE ALL ABSENT IN VIRUSES BESIDES NUCLEIC ACID IS PRESENT IN A VIRUS
A medical laboratory scientist is using phages to determine the species of bacterium in a culture. A phage produces a clear zone in a lawn of bacteria of the exact type infected by that phage. The clear zone of phage infection in a bacterial lawn is called . a prophage a plaque naked a zone of inhibition
B
Bacteriophages can use all of the following structures for attachment to a bacterial cell EXCEPT __________. pili the cytoplasmic membrane flagella the cell wall
B
How does the replication of animal RNA viruses differ from that of animal DNA viruses? A. The type of capsid the virus has B. The method of RNA synthesis and the nucleic acid that serves as template for viral replication C. Whether the virus is enveloped or not D. The mode of entry
B
How is latency of animal viruses different from lysogeny of phages? A. Latency involves enveloped viruses, while lysogeny does not. B. Animal viruses are not induced or excised from the host's DNA. C. Latent viruses emerge from the cell by lysis; lysogenic viruses bud from the cell. D. Latency involves RNA viruses; lysogeny involves DNA viruses.
B
A eukaryotic cell infected with an enveloped virus can shed viruses slowly over time, even throughout many years. Such an infection . is called a lytic infection is a prophage cycle is called a chronic or persistent infection is caused by a quiescent virus
C
A nursing student is studying antiviral drugs. Which of the following statements is true concerning viruses? Viruses move toward their host cells. Viruses are capable of metabolism. Viruses lack a cytoplasmic membrane. Viruses grow in response to their environmental conditions.
C
Fertilized chicken eggs are useful for the culture of viruses for all of the following reasons EXCEPT that __________. they are essentially large cells they are free of contaminating microbes they allow bacteriophages to become latent they are self-sufficient
C
Viruses lack all of the following EXCEPT __________. cytosol nucleic acids a cytoplasmic membrane organelles right answer feedbac
C
What is transduction? A. Viral DNA enters a new host. B. During viral release from a cell, some of the host DNA sticks to the outside of the virion and is transmitted into the next cell. C. Host DNA is packaged into a viral capsid by chance and is transferred to a new host cell. D. DNA from the virus is introduced into a new host cell when the tail of the virus punctures the host nucleus.
C
1. uncoating 2. prophage 3. retrovirus 4. bacteriophage 5. capsid 6. envelope 7. virion 8. provirus 9. benign tumor 10. cancer A. dormant virus in a eukaryotic cell B. a virus that infects a bacterium C. transcribes DNA from RNA D. protein coat of virus E. a membrane on the outside of a virus F. complete viral particle G. inactive virus within bacterial cell H. removal of capsomeres from a virion I. invasive neoplastic cells J. harmless neoplastic cells
H G C B D E F A J I
The _______replication cycle in bacteriophages results in the death of the cell.
LYTIC
Viruses can specifically infect one type of cell within an organism. True False
T
Viruses have genomes of DNA or RNA but NEVER both. True False
T
Viruses specifically infect only one type of cell within an organism. True False
T
What are the differences between DNA and RNA? A. The RNA backbone is made up of ribose sugars and phosphate, while the DNA backbone is made up of deoxyribose sugars and phosphate; further, RNA uses uracil nucleotide whereas DNA uses thymine nucleotide. B. Pyrimidines found in RNA are thymine and cytosine. C. DNA always functions as genetic material, whereas RNA is only used for protein synthesis. D. RNA is usually a double helix, while DNA is usually single stranded.
a
The ___________ stage of the viral life cycle is usually a spontaneous process, although in some viruses it is controlled by enzymes.
assembly
Why do viruses have to infect host cells? They infect host cells in order to steal the cell's genome. They cannot survive outside a host cell. They are dependent on host cell organelles and enzymes for their replication. They infect host cells in order to cause tumors.
c
cientists have determined that prion diseases are not caused by a type of slow virus because prions __________. are actually a type of viroid are too large to infect cells contain no nucleic acid kill infected individuals relatively quickly
c
Most viruses infect only a particular type of host cell. This specific targeting is primarily because __________. RNA viruses may use ribozymes to enter a cell capsomeres become enzymatic and digest cell membranes and walls viruses that are helical bore into a host cell of the precise affinity of a virus surface protein for the complementary proteins on the surface of the host cell of the precise affinity of a virus surface protein for the complementary proteins on the surface of the host cell
d
Which of the following is a major difference between a lysogenic and a lytic cycle in bacteriophages? Viral DNA is inserted into the bacterial cell only in a lytic cycle. The bacteriophage attaches to bacterial surface receptor proteins only in a lysogenic cycle. Only lytic cycles can be caused by DNA-containing bacteriophages. Viral DNA becomes a physical part of the bacterial chromosome only in a lysogenic cycle.
d
The most common type of polyhedral capsid is a(n)_____________.
icosahedron
A prophage is excised from the host chromosome and viral replication proceeds in a process called________
induction
An infection in which a host cell sheds new viruses slowly and steadily is called a(n) ___________- infection.
persistent
A technique used to estimate the numbers of bacteriophages in a culture is called a(n) __________ assay.
plaque