BIO205 Chapter 12

The poxviruses, which include examples such as smallpox and cowpox (vaccinia) virus, exhibit which morphological type? Choose one: A. Helical B. Icosahedral C. Amorphous D. Tailed

C. Amorphous

Which of the following is NOT a stage in the lytic cycle? Select one: a. Phage DNA integrates into host genome to form prophage. b. Cell synthesizes phage capsid proteins. c. Cell replicates phage DNA. d. Phage lyses the cell.

a. Phage DNA integrates into host genome to form prophage. FEEDBACK: The integration of phage DNA into the host genome is part of the lysogenic cycle. All other answer choices occur in the lytic cycle. See section 12.3 in your text for more information.

An example of a DNA viral genome is ________. Select one: a. herpes b. HIV c. influenza d. hepatitis C

a. herpes FEEDBACK: Herpes contains DNA as its genetic information. All other answer choices contain RNA genomes with one as a retrovirus. See section 12.2 in your text for more information.

An example of an RNA viral genome is ________. Select one: a. influenza b. herpes c. HPV d. There are no viral RNA genomes

a. influenza FEEDBACK: Influenza contains RNA as its genetic information. All other answer choices are incorrect. See section 12.2 in your text for more information.

When the (A) _____________ cycle takes place, bacteriophage genetics enter a cell, and then the cell makes many more bacteriophages and soon lyses. When the (B) _______________ cycle takes place, phage DNA integrates into the bacterial chromosome and simply replicates along with chromosomal replication.

lytic, lysogenic

The influenza genome that is delivered to the infected cell is ______ strand RNA.

negative

Integration of the human papillomavirus (HPV) genome into the DNA of a host cell may cause abnormal activation of _____________ that leads to cancer.

oncogenes

Transformation

1. The internalization of free DNA from the environment into bacterial cells. 2. The viral conversion of a normal cell to a cancer cell.

Virulent phage

A bacteriophage that reproduces entirely by a lytic cycle.

Plaque

A cell-free zone on a lawn of bacterial cells caused by viral lysis.

Baltimore model

A classification scheme that organizes viruses by genome type and method of replication; was devised by David Baltimore.

Oncogene

A gene that, through mutation or inappropriate expression, can lead to cancer.

Surface receptor

A host cell membrane protein that is recognized and bound by a microbe having a complementary binding molecule on its surface.

Syncytium

A large multinucleated cell formed by the fusion of many uninuclear cells.

Antigenic shift

A major change in a viral antigen that occurs when two (or more) strains of a virus with segmented genomes infect the same host cell and re-sort their genome segments. The resulting chimeric virus can express a new combination of surface antigens (such as influenza hemagglutinin and neuraminidase) that can alter virulence or enable the infection of new hosts.

Plaque-forming unit (PFU)

A measure of the concentration of phage particles in liquid culture.

Lentivirus

A member of a family of retroviruses with a long incubation period. An example is HIV.

Retroelement

A mobile genetic element in the genome of an organism.

Virus

A noncellular particle containing a genome that can replicate only inside a host cell.

Temperate phage

A phage capable of lysogeny.

Prophage

A phage genome that has integrated into a bacterial host genome.

Reading frame

A sequence of nucleotides in DNA or RNA whose nonoverlapping triplets are potentially translatable into a polypeptide.

Cloning vector

A small genome, often a plasmid, into which foreign DNA can be inserted for cloning.

Provirus

A viral genome that is integrated into the host cell genome.

Spike protein

A viral glycoprotein that connects the membrane to the capsid or the matrix and may be involved in viral binding to host cell receptors.

Lytic infection

A viral life cycle in which progeny virions are released from the host cell by virus-induced rupturing of the cell membrane.

Lysogeny

A viral life cycle in which the viral genome integrates into and replicates with the host genome but retains the ability to initiate host cell lysis.

Filamentous virus

A virus consisting of a helical capsid surrounding a single-stranded nucleic acid.

Virion

A virus particle.

Which part of the influenza virion facilitates interaction between the virus and the to-be-infected eukaryotic host cell? Choose one: A. Hemagglutinin B. Matrix protein C. An ion channel D. Neuraminidase

A. Hemagglutinin

Why was oseltamivir administered to Aisha? Choose one: A. Oseltamivir effectively blocks influenza viruses from completely replicating. B. Oseltamivir is effective in treating the symptoms associated with the flu. C. Oseltamivir is an attachment antagonist; it blocks viruses from entering cells. D. Oseltamivir is an immune system booster that causes more antibody production.

A. Oseltamivir effectively blocks influenza viruses from completely replicating.

In 2009, a retrovirus was successfully used to treat two children with an inherited genetic disease. What genetic disease was cured in these two children? Choose one: A. X-linked adrenoleukodystrophy B. X-linked red/green colorblindness C. Muscular dystrophy D. Cardiomyopathy

A. X-linked adrenoleukodystrophy

What do the H and N in H1N1 represent? Choose one or more: A.H represents hemagglutinin. B.H represents hematopoiesis. C.N represents neuraminidase. D.N represents neurological

A.H represents hemagglutinin. C.N represents neuraminidase.

Retrovirus

Also called RNA reverse-transcribing virus. A single-stranded RNA virus that uses reverse transcriptase to generate a double-stranded DNA copy of its genome.

Bacteriophage

Also called phage. A virus that infects bacteria.

RNA reverse-transcribing virus

Also called retrovirus. A single-stranded RNA virus that uses reverse transcriptase to generate a double-stranded DNA copy of its genome.

Reverse transcriptase

An enzyme that produces a double-stranded DNA molecule from a single-stranded RNA template.

RNA-dependent RNA polymerase

An enzyme that produces an RNA complementary to a template RNA strand.

Prion

An infectious agent that causes propagation of misfolded host proteins; consists of a defective version of the host protein.

Viroid

An infectious naked nucleic acid.

Which of the following is important to the mechanism by which an internalized influenza virus escapes its envelope? Choose one: A. Neutral pH in the lysosome B. Acidic pH in the lysosome C. Basic pH in the lysosome D. None of these is involved.

B. Acidic pH in the lysosome

Why was the HPV wart a raised and noticeable disruption within the normal skin on Sean's penis? Choose one: A. HPV invades skin cells and causes them to apoptose and aggregate. B. HPV causes cells to replicate faster, thereby creating a mass of cells. C. HPV enters bacterial cells and causes the colony to adhere to skin. D. HPV can only grow on top of epithelial cells, so growth is outward.

B. HPV causes cells to replicate faster, thereby creating a mass of cells.

Viruses use a relatively small number of virus-encoded proteins to take over the metabolism of their host cell. What implication(s) does this fact have on medical therapy? Choose one or more: A.Antiviral agents are so successful that most viral disorders are now completely eradicated. B.Antiviral agents are difficult to discover. C.Viral genomes have a fast mutation rate, even faster than that of bacteria. D.Antiviral agents have severe side effects.

B.Antiviral agents are difficult to discover. C.Viral genomes have a fast mutation rate, even faster than that of bacteria. D.Antiviral agents have severe side effects.

All successful viral replication cycles must, at minimum, achieve which of the following tasks? Choose one or more: A.Mutation within the genome B.Assembly of progeny virions C.Host recognition and attachment D.Exit of virions and transmission E.Genome entry into host cell

B.Assembly of progeny virions C.Host recognition and attachment D.Exit of virions and transmission E.Genome entry into host cell

Which of the following conclusions can be made from Sean's situation? Choose one: A. Sean must have acquired the virus from a woman he had sex with. B. Sean must have acquired the virus from experimenting sexually with other men. C. Sean must not have received the Gardasil vaccine. D. Sean must not have used condoms during any sexual experience.

C. Sean must not have received the Gardasil vaccine.

Envelope

For a virus, a membrane enclosing the capsid, or core particle.

One-step growth curve

Graphical representation of a lytic virus life cycle -- from attachment through infection, formation of progeny, and cell lysis -- in a system with a fixed number of host cells.

Antigenic drift

Random mutations in a viral genome that cause minor changes in the structure of viral surface antigens, such as influenza hemagglutinin and neuraminidase. The consequence is a new viral strain that might better evade the host immune system.

Tegument

The contents of a virion between the capsid and the envelope.

Batch culture

The growth of bacteria in a closed system without additional input of nutrients; oxygen may be provided.

Transmission

The movement of a pathogen from one host to another.

Burst size

The number of virus particles released from a lysed host cell.

Reassort

The process by which genome segments come together from different influenza strains infecting the same host cell.

Capsid

The protein shell that surrounds a virion's nucleic acid. Within an enveloped virus, such as HIV, the capsid may be called a core particle.

Tissue tropism

The range of host tissue that a pathogen can infect.

Uncoating

The release of a viral genome from its capsid, following entry of the virion into a host cell.

Lysis

The rupture of the cell by a break in the cell wall and membrane.

Host range

The species that can be infected by a given pathogen.

Eclipse period

The time after viral genome injection into a host cell but before complete virions are formed.

Transduction

The transfer of host genes between bacterial cells via a bacteriophage.

After binding to the host cell surface receptor, bacteriophage DNA is... Select one: a. injected into the host cell. b. released into the extracellular environment. c. degraded and transported into the host cell. d. used to inject the capsid proteins into the host cell

a. injected into the host cell. FEEDBACK: Bacteriophage DNA is injected into the host cell after binding to the host cell surface receptor. All other answer choices do not occur. See section 12.3 in your text for more information.

Which of the following is NOT a type of viral evolution? Select one: a. Viruses evolve within a host community to infect different species. b. Within an organism, viruses evolve to become noninfectious. c. Within a viral population, different viral strains that vary in infectivity arise. d. Within an individual organism, viruses evolve variants that resist therapeutic agents.

b. Within an organism, viruses evolve to become noninfectious. FEEDBACK: Viral evolution can occur through the following means: a virus evolving within a host community to infect various species, a virus evolving to include different viral strains of varying infectivity, and a virus evolving within a single organism to a from that resists therapeutic agents. A virus does not evolve within an organism to become noninfectious. See section 12.2 in your text for more information.

Which of the viral capsid morphologies shows radial symmetry? Select one: a. filamentous b. icosahedral c. radial d. amorphous

b. icosahedral FEEDBACK: Icosahedral viruses show radial symmetry. All other choices do not. See section 12.1 in your text for more information.

HPV replicates when ________________ Select one: a. infecting basal cells. b. keratinocyte differentiation occurs. c. binding to the CD4 receptor. d. treated with antiviral drugs.

b. keratinocyte differentiation occurs. FEEDBACK: HPV replicates when keratinocytes differentiate as they are actively growing. All other answer choices are incorrect and/or related to different viruses. See section 12.4 in your text for more information.

Worldwide, 1% of the population is infected with ________. Select one: a. hepatitis b. influenza c. HIV d. HPV

c. HIV FEEDBACK: HIV is experienced by 1% of human beings. See section 12.6 in your text for more information.

Which of the following IS part of the lysogenic cycle? Select one: a. Cell synthesizes phage capsid proteins. b. Cell replicates phage DNA. c. Phage DNA integrates into host genome to form a prophage. d. Phage lyses the cell.

c. Phage DNA integrates into host genome to form a prophage. FEEDBACK: The integration of phage DNA into the host genome is part of the lysogenic cycle. All other answer choices are incorrect. See section 12.3 in your text for more information.

The genome of HPV is ________________. Select one: a. single-stranded RNA b. double-stranded RNA c. double-stranded DNA d. single-stranded DNA

c. double-stranded DNA FEEDBACK: HPV contains a double-stranded DNA genome. See section 12.4 in your text for more information.

The ability of the influenza genome to undergo ________________ makes it capable of evolving novel strains that cause global pandemics. Select one: a. reverse transcription b. budding c. gene reassortment d. endocytosis

c. gene reassortment FEEDBACK: Gene reassortment in influenza can result in completely novel viral strains that cause global pandemics. See section 12.5 in your text for more information.

What is the purpose of the envelope spike proteins? Select one: a. to help with viral genome replication b. to disassemble the virus c. to attach and infect the host cell d. to solubilize aberrant proteins

c. to attach and infect the host cell FEEDBACK: A virus uses envelope spike proteins to bind to the receptors to the host cell. All other answer choices are related to different viral structures or are not a role of any viral structure. See section 12.1 in your text for more information.

What would happen if the hemagglutinin spike were removed from the influenza viral envelope? Select one: a. The virus would be unable to bud. b. The virus would be unable to remove its capsid. c. The virus would be unable to translate its RNA into proteins. d. The virus would be unable to bind to its surface receptor.

d. The virus would be unable to bind to its surface receptor. FEEDBACK: Hemagglutinin, a substance that causes red blood cells to stick together to form a mass, is important for binding the influenza virus to its cell surface receptor. All other answer choices have nothing to do with the role of hemagglutinin. See section 12.5 in your text for more information.

Prions are composed of ________. Select one: a. nucleic acids b. sugars c. normal proteins d. aberrant proteins

d. aberrant proteins FEEDBACK: Prions are composed of aberrant, misfolded proteins that interact with normal proteins to form more misfolded proteins. All other answer choices are incorrect. See section 12.2 in your text for more information.

What is a positive use for retroviruses? Select one: a. infection b. vaccines c. antivirals d. gene therapy

d. gene therapy FEEDBACK: Retroviruses are single-stranded RNA viruses that use reverse transcriptase to generate a double-stranded DNA copy of their genome. They are so good at delivering their material that they are good to use in gene therapy. See section 12.6 in your text for more information.

What enzyme ensures HIV infection is permanent? Select one: a. reverse transcriptase b. protease c. entrase d. integrase

d. integrase FEEDBACK: Integrase results in the integration of the HIV genome into the host cell, ensuring a permanent infection. All other answer choices are incorrect. See section 12.6 in your text for more information.

The viral-encoded enzyme required by HIV during its infection is _______________. Select one: a. RNA polymerase b. DNA polymerase c. dehydrogenase d. reverse transcriptase

d. reverse transcriptase FEEDBACK: HIV requires reverse transcriptase, which it must code for and bring itself as humans do not express it. See section 12.6 in your text for more information.

When culturing bacteriophage, at what point do the phage particles begin appearing in the growth medium? Select one: a. lysogenic period b. latent period c. eclipse period d. rise period

d. rise period FEEDBACK: The rise period is when phage particles begin appearing. All other answer choices are either earlier (eclipse period) or are not related to phage particles appearing in growth medium. See section 12.3 in your text for more information.

The presence of ________________ is a bizarre feature of the influenza virus genome. Select one: a. RNA b. DNA c. matrix proteins d. segmented RNA genome

d. segmented RNA genome FEEDBACK: The segmented RNA genome in influenza is bizarre. All other answer choices are incorrect. See section 12.5 in your text for more information.

HPV causes cancer through increased expression of Select one: a. cell surface receptors. b. antigens. c. tumor suppressor genes. d. viral oncogenes.

d. viral oncogenes. FEEDBACK: HPV encodes viral oncogenes that help it to cause cancer. All other answer choices are incorrect. See section 12.4 in your text for more information.