Chapter 5 and 6
If the following RNA molecule is reverse transcribed, what would be the resulting sequence?RNA 5' - GAC UAC GUU GAA - 3'
5' - TTC AAC GTA GTC - 3'
According to the animation, ribosomes move along the mRNA in which direction?
5' to 3'
During elongation, how is the RNA synthesized?
5' to 3'
Cells can only contain which of the following types of genomes?
A double-stranded DNA genome
What kind of bond is formed when two amino acids join together?
A peptide bond
What results from the process of translation?
A polypeptide
In the Spring of 2009, a novel H1N1 virus emerged that had a new combination of genes from pigs, humans, and birds. As a result, the virus spread quickly, resulting in a swine flu pandemic. Which of the following concepts explains why the outbreak occurred?
Antigenic shift
Which of the following steps is found in the lysogenic replication pathway but not in the lytic replication pathway?
Integration
Despite close contact, what is the most likely explanation for why Miley's roommates didn't develop the same signs and symptoms as she did?
Miley's friends likely already had the disease as children, without knowing it.
Bacteriophages use different mechanisms for host cell infection and viral replication. During the lytic replication pathway, bacteriophages infect the host bacterial cells and immediately build new virions. During which of the key steps is the genome packed into capsid and phage structures put together?
Assembly
In which stage does formation of mature viruses occur?
Assembly
Which replicative step(s) do animal viruses and bacteriophages have in common? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. Assembly Uncoating Penetration Attachment
Assembly Penetration Attachment
How is bacterial translation different from eukaryotic translation?
Bacteria can begin translation before transcription has terminated.
Which of the following methods is used to cultivate bacteriophages in the laboratory setting?
Bacteriophages are cultivated in bacteria in liquid broth or on solid medium.
Which statement is not true about the virus capsid?
Because the capsid is not essential to the virus, it is not a useful target for antiviral drugs.
How would Miley's kidney dysfunction lead to signs and symptoms of a swollen abdomen, swollen ankles, and a decreased urine output? (NCLEX style)
Miley's kidneys could not produce sufficient urine, so fluid began to build up in her abdomen and other tissues.
Which of the following names represents a viral order?
Mononegravirales
The host DNA is usually degraded during which stage?
Biosynthesis
Which of the following is not a mechanism of an antiviral drug?
Blocking viral ribosomes
Which of the following observations supports the statement that cytomegalovirus (CMV) has a remarkably broad tropism?
CMV can infect connective tissue cells and parenchymal cells of virtually any organ.
Epstein-Barr virus is a _____ virus and, therefore, has a _____-based genome.
herpes; DNA
Which picture shows an icosahedral enveloped virus with spikes?
icosahedral virus with circular envelope with spikes
Which of the following is an example of a spontaneous mutation?
DNA polymerase III accidentally mismatches a G to a T during Escherichia coli DNA replication, resulting in a silent mutation.
The primary flow of genetic information in cells is from
DNA → RNA → protein.
All persistent viral infections occur when the virus integrates into the host cell DNA to form a provirus.
False
Both viruses and prokaryotes reproduce by binary fission.
False
Like bacteriophage, when an animal cell virus enters a host cell, only the genome enters while the capsid remains outside the cell.
False
Naked viruses usually exit the animal host cell by budding while enveloped viruses exit by lysis.
False
The shape of a virus may be determined by either its capsid or its envelope.
False
Why is there a need to be vaccinated with a new flu shot every year?
The RNA genome of influenza mutates frequently, causing minor changes. This is referred to as antigenic drift.
Which of the following suffixes would be used to describe a viral family?
-viridae
How does the ribosome know if the entering charged tRNA is correct?
The anticodon on the tRNA base pairs to the codon on the mRNA.
Which of the following are contributors to viral genome evolution?
quick replication time and the large number of virions released within a host
Ribosomes contain which of the following?
rRNA
What would happen if the mRNA codon that coded for Cys was mutated in the third position from a U to an A?
A stop codon would be introduced prematurely.
Which of the following is a major difference between bacteriophages and animal viruses?
Animal viruses enter the host cell; bacteriophages inject their genome into the host without entering.
Which description of antigenic drift and antigenic shift in the influenza virus is incorrectly matched?
Antigenic drift: Often involves reassortment of viral strains in an animal host followed by a "species jump" to humans.
An elderly patient who contracted chickenpox as a child now has shingles as an adult. You explain to your patient that both diseases are caused by the same virus, which lays dormant in the body prior to reactivation. Based on this information, choose the true statement.
During dormant periods, the virus exists episomally inside of infected host cells.
Which of the following oncogenic viruses may integrate into the host genome?
Human papilloma viruses (HPVs)
Which of the following terms is used to describe the shape of a virus?
Icosahedral
Where would one find an uncharged tRNA molecule in a ribosome?
In the P and E sites
How would one increase the concentration of a particular polypeptide in a cell?
Increase the level of transcription
Miley's treatment plan included reducing the dose of her immuno-suppressive drugs. Why did this help her overcome the cancer? (NCLEX style)
It allowed her immune system to become more active and kill the cancer cells.
Which of the following statements about transcription in prokaryotes is false?
It occurs in the nucleus.
Which type of method is used to determine if a prior exposure to a virus occurred?
Latex agglutination test
The anticodon of a tRNA molecule is 3' - GUA - 5.' This tRNA molecule should allow which amino acid to be incorporated into a growing protein chain? (Use the following condensed mRNA codon table to assist you with this question). 5' - GUA - 3' - Valine 5' - UAC - 3' - Tyrosine 5' - AUG - 3' - Methionine 5' - CAU - 3' - Leucine
Leucine
Which of the following statements incorrectly describes viral spikes?
Lipid-based spikes make up the envelope that surrounds the capsid.
Which statement is not true about chronic persistent viral infections?
May involve periods of flare-up where the virus is actively replicating alternating with periods of dormancy.
________ RNA carries a genetic message in triplet code (codons) and is translated to build a protein.
Messenger
As shown in the animation, the start codon also codes for which amino acid?
Methionine
Which of the following accurately describe Epstein-Barr virus? Select all that apply. (NCLEX style) Treatable with anti-retroviral medications Oncogenic Latent Persistent
Oncogenic Latent Persistent
During the initiation step of translation, the fMet charged tRNA assembles in which site of the ribosome?
P site
A rapid Strep test is often used in the clinic to determine whether a patient is infected with Streptococcus. After swabbing the patient's throat, the sample is mixed with specified reagents and then applied to a diagnostic strip. As the sample moves up the strip, various lines will appear or not appear, depending on the reaction. The "C" line is the positive control-it should always appear. The "T" line is the test-it should only appear if the result is positive. Two samples come into the clinic lab, and the following results are obtained. How would you interpret these results? (NCLEX style) Patient 1- C line and T line Patient 2- T line only
Patient 1 has Strep throat; Patient 2's results are inconclusive and must be redone. Submit
In which stage is the viral DNA introduced into the cell?
Penetration
RNA is distinguished from DNA because only RNA:
typically exists as a single-stranded molecule.
Which of the following acellular agents do not have any genetic material and therefore do not replicate?
Prions
According to the animation, which of the following makes mRNA from the information stored in a DNA template?
RNA polymerase
Retroviruses, such as human immunodeficiency virus, rely on reverse transcriptase to multiply inside a cell. However, HIV also requires host ribosomes to build new viral particles. Based on your knowledge of the central dogma, order the flow of genetic information from left-to-right, from the first step (left) to the last step (right), for retroviruses.
RNA, DNA, RNA, Protein
Which of the following genome types has been observed in viruses? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. Single-stranded DNA Protein-based Double-stranded RNA Single-stranded RNA
Single-stranded DNA Double-stranded RNA Single-stranded RNA
How many codons code for the amino acid arginine?
Six
Choose the true statement about protein synthesis.
The first amino acid in a eukaryotic protein sequence is methionine, whereas the first amino acid in a prokaryotic protein sequence is formyl methionine.
Choose the true statement about the genetic code.
The genetic code is redundant, with multiple codons specifying a single amino acid.
What is the initial target of RNA polymerase?
The promoter
A newly-discovered double-stranded RNA virus which infects animal cells is found to contain a unique enzyme which synthesizes double-stranded RNA using an RNA template. Which of the following statements is likely to be true?
The virus must bring this enzyme into the host cell as synthesizing RNA from an RNA template does not happen in animal cells.
You observe that a novel virus penetrates the host cell through membrane fusion. Which of the following statements must also be true regarding this virus and its replicative cycle?
The virus releases from host cells by budding.
What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?
The virus would not be able to infect new hosts.
Which of the following amino acids is coded by only one codon?
Trp
Which of the following is (are) used to classify viruses? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. Viral genome size Type of nucleic acid present Capsid symmetry Viral particle size
Type of nucleic acid present Capsid symmetry
Choose the true statement(s) about stop codons. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer.
Under specific circumstances, stop codons may encode non-standard amino acids. There are several stop codons in the genetic code.
Which of the following are ways that viruses differ from prokaryotes and eukaryotes? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. Unlike prokaryotes and eukaryotes, viruses do not have genomes. Unlike prokaryotes and eukaryotes, viruses are not considered alive. Unlike prokaryotes and eukaryotes, viruses are classified as acellular particles. Unlike prokaryotes and eukaryotes, viruses are incapable of replicating independently from a host cell.
Unlike prokaryotes and eukaryotes, viruses are not considered alive. Unlike prokaryotes and eukaryotes, viruses are classified as acellular particles. Unlike prokaryotes and eukaryotes, viruses are incapable of replicating independently from a host cell.
Which of the following would be the best general description of a "virus?"
Viruses are acellular infectious agents.
Viruses do not infect which of the following organisms?
Viruses can infect all forms of life.
Miley did not go to the doctor because she presumed her sore throat was caused by a virus, and no treatment would be available. Why is it more difficult to treat a viral infection than a bacterial one?
Viruses use our host cell machinery to replicate. Bacteria do not.
How is translation terminated?
When a protein called a release factor enters and binds to the A site
Which genomic arrangement has not been found in viruses?
a combination of DNA and RNA in the same virus
Drag the correct labels onto the diagram to identify the structures and molecules involved in translation.
a) mRNA b) Small subunit of ribosome c) Large subunit of ribosome d) Amino acid e) tRNA f) Anticodon
In a(n) _________ infection, viral replication peaks, followed by immune clearance of the virus.
acute
Viral spikes
allow the virus to attach and enter host cells, may be a target for the host immune system, and show specificity in binding to particular structures on the host cell.
Compared to both prokaryotic and eukaryotic cells, viruses
are generally smaller.
GAU codes for
aspartic acid.
Which stage of animal virus replication may be blocked by a drug that binds with the viral spike?
attachment
Nucleic acid detection techniques:
can detect new viruses and early-stage infections that antibody-antigen tests are likely to miss.
The protein shell that packages and protects the genome and also accounts for the bulk of a virion's mass is called a _________.
capsid
Retroviruses use the enzyme reverse transcriptase to
direct the production of DNA from a single-stranded RNA genome.
During lytic replication of bacteriophage, which process uses factors from the host cell, rather than coded by the viral genome?
enzymes which transcribe and translate viral genes
When a virus has an envelope,
it likely escapes its host cell by budding.
Which of the following can be translated into protein?
mRNA
Transcription produces which of the following?
mRNA, tRNA, and rRNA are all produced by transcription.
All viruses must use their genome to produce ________, which is then used by the host cell to produce ________.
mRNA; proteins
The most common drugs that block replication are ________.
nuceloside analogs
Which stage of animal virus replication will not be different between naked viruses and enveloped viruses?
replication
Naturally occurring mutations are often referred to as ________ mutations.
spontaneous
Which of the following viral genomes is immediately ready for translation after the virus gains entry into the cell?
ssRNA+
RNA that has hydrogen bonded to itself forms a
stem loop.
Which of the following is involved in bringing amino acids to the ribosomes?
tRNA
RNA polymerase is guided by the
template strand of DNA.
The rabies virus primarily affects the nervous system. The specificity that the rabies virus has for neuronal host cells is primarily dictated by __________________________.
the spikes that protrude from its viral envelope
Viruses are considered to be non-living pathogens for which reason?
their lack of metabolic processes
A previously undescribed infection has been detected among inhabitants in an isolated village in a remote tropical rainforest. When serum from an infected individual is passed through a filter, the infection can be transmitted to laboratory animals. Nothing is observed when the serum is examined with a light microscope at the highest magnification. Biochemical tests show the presence of RNA and protein but no carbohydrates or lipids. This data is consistent with what type of infectious agent?
virus
Challenges in developing effective antiviral drugs with minimal side effects to the patient include
viruses use the cell's own machinery and metabolism for replication.