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What are the genetic materials found in viruses?
Viruses can have either DNA or RNA as their genetic material.
What types of strands can viruses have?
Viruses can have double-stranded, single-stranded, or segmented strands of genetic material.
What are viroids made of?
Viroids are made of single-stranded RNA.
What do viroids infect?
Viroids primarily infect plants.
What do viroids cause in plants?
Viroids cause diseases in plants.
What is the function of the (+) strand?
The (+) strand can be translated immediately.
How does the (+) strand relate to mRNA?
The (+) strand has the same orientation as mRNA.
What must happen to the (-) strand before translation?
The (-) strand has to be copied before it can be translated.
What enzyme does a retrovirus carry?
A retrovirus carries reverse transcriptase.
What does reverse transcriptase do in a retrovirus?
Reverse transcriptase copies single-stranded RNA into double-stranded DNA.
What happens to the double-stranded DNA in a retrovirus?
The double-stranded DNA becomes a chromosome in a latent state.
What do vaccination programs develop?
Vaccination programs develop herd immunity.
What type of infections can reovirus cause?
Reovirus can cause respiratory and enteric (diarrhea) infections.
Why is reovirus called an orphan virus?
Reovirus is called an orphan virus because it is not associated with a specific disease.
What disease does rhabdovirus cause?
Rhabdovirus causes rabies.
What common illness is caused by coronavirus?
Coronavirus causes the common cold.
Why is coronavirus named "corona"?
Coronavirus is named "corona" because of its spiked proteins that stick out of the envelope, resembling a crown.
What are some other names for coronavirus?
Other names for coronavirus include COVID, SARS, and MERS.
What disease is caused by retrovirus?
Retrovirus causes HIV, which has reverse transcriptase.
What disease does the polio virus cause?
The polio virus causes polio.
What disease does parvovirus cause?
Parvovirus causes parvo, which leads to diarrhea.
What animals are commonly affected by parvovirus?
Puppies are commonly affected by parvovirus.
What disease is caused by varicella zoster?
Varicella zoster causes chickenpox, which can later lead to shingles.
What does HPV stand for?
HPV stands for human papillomavirus.
What are some conditions caused by HPV?
HPV can cause genital warts and cervical cancer.
What tissue does adenovirus infect?
Adenovirus infects the adenoids, which are lymphatic tissues in the face.
What disease does pox virus cause?
Pox virus causes smallpox.
What was the first vaccine created for?
The first vaccine was created for smallpox.
Why has smallpox been eradicated?
Smallpox has been eradicated because humans are the only host, and vaccination removed the virus’s host, causing it to die out.
What type of phage is lambda, and what does it infect?
Lambda is a lysogenic phage that infects E. coli.
What type of phage is T4, and what does it infect?
T4 is a lytic phage that infects E. coli.
What type of viruses belong to the herpesvirus family?
Herpesvirus includes latent viruses.
What are the types of herpes simplex viruses and their associated conditions?
Herpes simplex I causes fever blisters, and herpes simplex II causes genital herpes.
What disease is caused by the Epstein-Barr virus?
Epstein-Barr virus causes mononucleosis and is associated with Burkitt’s lymphoma, a cancer in young children.
What must a virus do to infect a specific host cell?
A virus must attach to receptors that are specific to the host cell.
What happens after a virus enters the host cell?
The virus undergoes absorption into the host and uncoats the nucleic acid from the capsid.
What occurs during the synthesis stage of viral replication?
The synthesis stage involves the production of viral nucleic acids and proteins.
What happens during the assembly stage of viral replication?
During assembly, new viruses are put together inside the host cell.
How are new viruses released from the host cell?
New viruses are released either by lysis, which breaks open the cell, or by budding, which helps form an envelope around the virus.
What does burst size refer to in viral replication?
Burst size refers to the number of viruses released after one cycle of infection.
What does the "H" in H1N1 influenza stand for?
The "H" in H1N1 influenza stands for hemagglutinin.
What does the "N" in H1N1 influenza stand for?
The "N" in H1N1 influenza stands for neuraminidase.
What is the function of neuraminidase in the H1N1 influenza virus?
Neuraminidase is an enzyme that allows the flu virus to spread between cells.
What is antigenic shift?
Antigenic shift is a major change in the genome.
What is antigenic drift?
Antigenic drift is a minor change in the genome.
How do RNA viruses mutate?
RNA viruses mutate spontaneously.
What organ do hepadnaviruses infect?
Hepadnaviruses infect the liver.
What are infectious proteins whose extracellular form contains only protein and no nucleic acid?
Infectious proteins whose extracellular form contains only protein and no nucleic acid are called prions.
How do prions affect normal prion proteins in the brain?
Prions cause normal prion proteins in the brain to change shape.
What is the result of prions causing normal prion proteins to change shape?
The result is the formation of plaques in grey matter, creating "holes" in the brain.
What are examples of diseases caused by prions?
Examples of diseases caused by prions include mad cow disease and kuru.
Distinguish between a positive-strand RNA virus and a negative strand RNA virus.
A positive-strand RNA virus has RNA that can serve directly as mRNA, while a negative-strand RNA virus carries RNA that must be transcribed into a complementary positive strand before translation.
Contrast mRNA production in the two classes of single stranded RNA viruses.
Positive-strand RNA viruses use their genome directly as mRNA, while negative-strand RNA viruses must carry an RNA-dependent RNA polymerase to synthesize mRNA from their genome.
What is unusual about genetic information flow in retroviruses?
Retroviruses reverse transcribe their RNA genome into DNA using reverse transcriptase, which is then integrated into the hosome.
What is unique about the Pox viruses? What type of damage do they do to their host?
Pox viruses replicate entirely in the cytoplasm rather than the nucleus, and they cause large, pus-filled skin lesions in their host.
Where in the body do you find adenoviruses?
Adenoviruses are commonly found in the respiratory tract, eyes, and gastrointestinal system.
Name at least two common diseases caused by herpesviruses.
Herpesviruses cause diseases such as herpes simplex (cold sores, genital herpes) and varicella-zoster (chickenpox and shingles).
What disease is associated with coronaviruses?
Coronaviruses are associated with diseases such as COVID-19 and SARS.
What is the shaped and name of the virus that causes rabies? What type of virus is it?
The rabies virus, known as Lyssavirus, has a bullet-shaped structure and is a negative-strand RNA virus.
What is antigenic shift and drift? Which virus are they associated with and why do they occur?
Antigenic shift is a major genetic reassortment leading to new viral subtypes, while antigenic drift is a gradual accumulation of mutations.
They are associated with influenza viruses and occur due to frequent changes in the viral genome.
What are reoviruses?
Reoviruses are double-stranded RNA viruses that can cause gastrointestinal and respiratory infections.
What type of virus is HIV? What does it cause?
HIV is a retrovirus that causes AIDS (acquired immunodeficiency syndrome).
What is the host cell for hepadnaviruses?
Hepadnaviruses, such as hepatitis B virus, primarily infect liver cells (hepatocytes).
Compare and contrast the various types of viral replication.
Viral replication can vary based on genome type, including lytic and lysogenic cycles, reverse transcription in retroviruses, and cytoplasmic replication in some DNA viruses like poxviruses.
What are viroids and what do they infect?
Viroids are small, circular RNA molecules that infect plants and interfere with their gene expression.
On what basis can prions be differentiated from all other infectious agents?
Prions are unique because they are infectious proteins that lack nucleic acids (DNA or RNA).
What is the difference between the native and pathogenic forms of a prion protein?
The native prion protein (PrPᶜ) is normally found in cells, while the pathogenic form (PrPˢᶜ) is misfolded and induces other proteins to misfold, leading to disease.
How does a prion differ from a viroid? How does a prion differ from a virus?
A prion is a misfolded protein with no genetic material, while a viroid is a small, circular RNA molecule without a protein coat.
A virus contains genetic material (RNA or DNA) and a protein coat.
Name some prion diseases and the organisms they are found in.
Prion diseases include Creutzfeldt-Jakob disease (humans), bovine spongiform encephalopathy (cattle, also known as mad cow disease), and scrapie (sheep).
True or False?
In order to replicate its genome, a positive-strand RNA virus must produce a complete negative-strand RNA molecule that serves as the template for protein synthesis.
False
You isolate 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 enzymes, amino acids, and RNAs necessary for translation. The RNA is translated directly, without being copied into a complementary strand first, and new infectious virions are made and released. What does this tell you about the bacteriophage?
The viral genome is ssRNA of the minus sense.
The bacteriophage is probably a new strain and should be studied further.
The viral genome is ssRNA of the plus sense.
The bacteriophage is a retrovirus.
The viral genome is ssRNA of the plus sense.
What is the purpose of synthesizing a negative strand of RNA in a positive ssRNA virus?
Enable rolling circle amplification of the genome, which requires both strands of RNA
Proofreading of the genome to minimize mutations generated by the polymerase being passed onto virion progeny
To serve as the complementary template sequence in genome amplification of the positive strand
Enable transcription of genes occurring on both the negative and positive strands of the genome, such as overlapping genes
To serve as the complementary template sequence in genome amplification of the positive strand
From which phrase is the term “prions” derived?
Particles of infection
Protein infection of the nervous system
Protein infections
Proteinaceous infectious particles
Proteinaceous infectious particles
In what year did Stanley Prusiner discover prions?
1928
1979
1997
1982
1982
Which disease did Stanley Prusiner first identify as being caused by prions?
Scrapie
Mad cow disease
Kuru
Fatal familial insomnia
Scrapie
How are prions different from other infectious agents?
They lack protein.
They lack nucleic acid.
They cause neurological disease.
They cannot replicate.
They lack nucleic acid.
Which type of viruses can be directly used for translation?
positive ssRNA
retroviruses
negative ssRNA
dsRNA
positive ssRNA
When two different influenza viruses infect the same cell, their segmented genomes can undergo reassortment which will result in
loss of hemagglutinin.
loss of neuraminidase.
antigenic drift.
antigenic shift.
antigenic shift.
True or False?
Viroids infect only fungi.
False
True or False?
In prokaryotes, DNA viruses replicate their genomes in the nucleus while RNA viruses are replicated in the cytoplasm.
False
The ________ has been especially useful for genetic engineering because it is capable of triggering a substantial immune response without causing major adverse health effects.
polyomavirus
adenovirus
herpesvirus
vaccinia virus
vaccinia virus
The normal function of the PrP protein in mammals is believed to be:
assisting in normal membrane development and function.
assisting proteins in forming alpha-helices.
assisting proteins in forming beta-pleated sheets.
assisting in normal synaptic development and function.
assisting in normal synaptic development and function.
How do normal prion proteins (PrP) differ from the infectious prion proteins?
Normal PrP are found in all mammals; infectious PrP are found in only cows.
Normal PrP lack nucleic acid; infectious PrP have nucleic acid.
Normal PrP have alpha-helices; infectious PrP have beta-pleated sheets.
Normal PrP are found on mammals; infectious PrP are found on reptiles.
Normal PrP have alpha-helices; infectious PrP have beta-pleated sheets.
How does the number of infectious prions increase?
Prions reproduce by binary fission.
Prions form multimers which can then form more single copies of the prion protein.
Prions reproduce by mitosis.
Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion.
Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion.
Why are the beta-pleated multimers of PrP potentially pathogenic?
The multimers are more stable and resistant to protease.
They are not detected by other organisms.
They repress the immune system.
They are found on the surface of immune cells, resulting in damage to the immune system.
The multimers are more stable and resistant to protease.
Which of the following prion diseases is found in deer and elk?
Scrapie
Variant Creutzfeldt-Jakob disease
Bovine spongiform encephalopathy
Chronic wasting disease
Chronic wasting disease
Which of the following prion diseases was also known as laughing disease?
Kuru
Bovine spongiform encephalopathy
Gerstmann-Straussler-Scheinker syndrome
Creutzfeldt-Jakob disease
Kuru
Which of the following conditions in humans is linked to bovine spongiform encephalopathy?
Variant Creutzfeldt-Jakob disease
Kuru
Gerstmann-Straussler-Scheinker syndrome
Fatal familial insomnia
Variant Creutzfeldt-Jakob disease
What part of the nervous system is most affected by fatal familial insomnia?
Thalamus
The spinal cord
Cerebellum
Cerebrum
Thalamus
Where does the name “scrapie” come from?
The disease results in the animal wasting away, sending them to the "scrap heap."
The prion disorder causes infected sheep to scrape against objects until their skin is raw.
The prions cause amyloid plaques to scrape against each other.
The prion disorder causes infected sheep to scrape against objects until their skin is raw.
Herpes viruses can cause all of the following diseases in humans EXCEPT
cold sores.
spongiform encephalopathy.
chicken pox.
cancer.
spongiform encephalopathy.
The HIV genome consists of
two identical ssDNA molecules.
a single dsRNA molecule.
two identical ssRNA molecules.
a single DNA molecule.
two identical ssRNA molecules.
