CHAPTER 6

What suffix would be used to describe a viral family?

-viridae

Cells can only contain which type of genomes?

A double-stranded DNA genome

Which of the following statements incorrectly describes viral spikes? A. Lipid-based spikes make up the envelope that surrounds the capsid. B. Spikes have an important role in determining what species and tissues the virus can infect. C. Spikes may be recognized by the host immune system that mounts an immune response to them. D. Spikes are glycoprotein extensions that help viruses attach and gain entry to host cells.

A. Lipid-based spikes make up the envelope that surrounds the capsid. *note:* Spikes (also called peplomers) protrude from the viral capsid or, if present, from the viral envelope and are made up of glycoproteins. These glycoprotein extensions help viruses attach and gain entry to host cells. Because they only bind to specific factors on a given host cell, spikes have an important role in determining what species and tissues the virus can infect, similar to how a lock and key must match. The host immune system may also recognize spikes and mount an immune response to them.

Which of the following is NOT a property used to group viruses? A. Unicellularity versus multicellularity B. Type of nucleic acid present (DNA or RNA) C. Presence or absence of an envelope D. Capsid symmetry (helical, icosahedral, or complex)

A. Unicellularity versus multicellularity

Which of the following is not a mechanism of an antiviral drug? A. Blocking viral ribosomes B. Blocking uncoating C. Blocking viral attachment D. Blocking viral penetration

A. blocking viral ribosomes

What is a major difference between bacteriophages and animal viruses?

Animal viruses enter the host cell; bacteriophages inject their genome into the host without entering. *note:* Among various differences between animal viruses and bacteriophages, one major difference between them is that animal viruses enter the host cell; bacteriophages inject their genome into the host without entering. Both animal viruses and bacteriophages are assembled in the cytoplasm of cells. Animal viruses are released from the cell by budding; bacteriophages are released by bursting.

Which of the following viral genomes is immediately ready for translation after the virus gains entry into the cell? A. ssDNA B. dsDNA C. ssRNA+ D. dsRNA

C. ssRNA+

Chlamydia trachomatis is an obligate intracellular bacterium that causes the sexually transmitted disease chlamydia. When this bacterium was first discovered, it was classified as a virus. However, it was later re-classified as a bacterium. What is the most likely the reason why C. trachomatis was reclassified as a living bacterial cell as opposed to a nonliving viral particle?

Chlamydia trachomatis is capable of performing metabolic processes.

Which of the following methods is used to cultivate bacteriophages in the laboratory setting? A. Bacteriophages are cultivated in embryonated eggs. B. Bacteriophages are cultivated in tissue cultures. C. Bacteriophages are grown with the streak plate method. D. Bacteriophages are cultivated in bacteria in liquid broth or on solid medium.

D. Bacteriophages are cultivated in bacteria in liquid broth or on solid medium.

Which of the following oncogenic viruses may integrate into the host genome? A. Hepatitis C viruses B. Epstein-Barr viruses C. Human herpes virus-8 D. Human papilloma viruses (HPVs)

D. Human papilloma viruses (HPVs)

what term describes the shape of a virus?

Icosahedral

In a(n) _________ infection, viral replication peaks, followed by immune clearance of the virus.

In an *acute* infection, viral replication peaks, followed by immune clearance of the virus.

What step is found in the lysogenic replication pathway but not in the lytic replication pathway?

Integration

What method is used to determine if a prior exposure to a virus occurred?

Latex agglutination test

arrange the following viruses from smallest to largest: Ebola virus, Poliovirus, Rhinovirus, and Pithovirus

Poliovirus, Rhinovirus, Ebola virus, Pithovirus

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

Nucleic acid detection techniques:

can detect new viruses and early-stage infections that antibody-antigen tests are likely to miss. *note:* Nucleic acid detection techniques can detect new viruses and early-stage infections that antibody-antigen tests are likely to miss. They are more sensitive and sometimes more rapid than antigen-antibody-based tests. To perform the test, DNA and RNA are extracted from a clinical sample such as sputum, blood, cerebrospinal fluid, or tissue. Then very specific segments of viral nucleic acid, usually those coding for a unique viral gene, can be detected by using fluorescence-labeled probes or by sequencing the nucleic acids.

The protein shell that packages and protects the genome and also accounts for the bulk of a virion's mass is called a ________.

capsid

what is the best general description of a "virus?"

Viruses are acellular infectious agents. *note:* Viruses are acellular infectious agents. However, unlike prokaryotes and eukaryotes, viruses are not cells, hence their descriptor "acellular." One reason viruses are considered nonliving is that viruses are incapable of synthesizing their own components, such as nucleic acids or proteins, without the help of the host cells they infect. They do not have any membrane-bound organelles, and their genomes are not always made up of double-stranded DNA. Viruses do not just contain double-stranded DNA genomes; some may contain single-stranded DNA genomes, and others contain single or double-stranded RNA genomes.

which organisms do viruses NOT infect?

Viruses can infect all forms of life *note:* Viruses can infect all forms of life, prokaryotes (bacteria and archaea) and eukaryotes (plants, protists, animals, and fungi). The structural and genomic features of a virus dictate what sort of host the virus can infect, as well as the progression of the infection.

The most common drugs that block replication are ________.

nuceloside analogs

what does the suffix "-virus" refer to?

the genus of a virus

what does the suffix "-virales" refer to?

the order

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.

Zika virus is best described as a(n) _________ virus with a ________ genome.

Zika virus is best described as an *enveloped* virus with a *ssRNA+* genome.

what does the suffix "-virinae" refer to

a subfamily

Which of the following acellular agents do not have any genetic material and therefore do not replicate? A. Bacteria B. Prions C. Archaea D. Protists

B. Prions