Microbiology Study Guide: Viruses, Viroids, and Prions

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Q1. Which one of the following is true regarding viruses?

Background

Topic: General Properties of Viruses

This question tests your understanding of the fundamental characteristics that distinguish viruses from other microorganisms.

Key Terms:

Virion: A complete virus particle.
Binary fission: A method of asexual reproduction typical of prokaryotes, not viruses.
Antibiotics: Drugs that target bacteria, not viruses.
Cell: The basic unit of life; viruses are acellular.

Step-by-Step Guidance

Review the definitions of each answer choice and recall the unique features of viruses compared to bacteria and other microbes.
Consider whether viruses contain both DNA and RNA, or just one type of nucleic acid.
Think about how viruses replicate—do they use binary fission or another method?
Recall whether antibiotics are effective against viruses or only against bacteria.
Determine if viruses are made up of cells or if they are acellular entities.

Try solving on your own before revealing the answer!

Q2. Which one of the following is NOT a morphological type of virus?

Background

Topic: Viral Morphology

This question assesses your knowledge of the structural types of viruses.

Key Terms:

Helical: Rod-shaped viruses with a spiral arrangement of capsomeres.
Polyhedral: Many-sided viruses, often icosahedral.
Enveloped: Viruses surrounded by a lipid membrane.
Polymorphic: Consider if this is a standard morphological classification.

Step-by-Step Guidance

List the main recognized shapes of viruses as described in your textbook or lecture notes.
Compare each answer choice to the standard morphological types.
Identify which term does not fit with the established categories.

Try solving on your own before revealing the answer!

Q3. Viruses that infect bacteria are called:

Background

Topic: Virus Host Range

This question tests your understanding of the terminology for viruses based on their host organisms.

Key Terms:

Bacteriophage: A virus that infects bacteria.
Prion: Infectious protein, not a virus.
Viroid: Infectious RNA, not a virus.
Poxvirus: A family of viruses, not specific to bacteria.

Step-by-Step Guidance

Recall the definition of each term listed in the answer choices.
Identify which term specifically refers to viruses that target bacteria.
Eliminate options that refer to non-viral infectious agents or viruses that infect other hosts.

Try solving on your own before revealing the answer!

Q4. The suffix -viridae is used for virus:

Background

Topic: Virus Taxonomy

This question is about the classification and naming conventions of viruses.

Key Terms:

Genus, Family, Order, Phylum: Levels of taxonomic classification.
-viridae: A suffix used in viral taxonomy.

Step-by-Step Guidance

Review the standard suffixes used for each taxonomic rank in viruses (e.g., -virus, -viridae, -virales).
Match the suffix -viridae to the correct taxonomic level.
Eliminate options that do not correspond to the -viridae suffix.

Try solving on your own before revealing the answer!

Q5. Capsids are composed of protein subunits known as:

Background

Topic: Viral Structure

This question tests your knowledge of the components that make up the viral capsid.

Key Terms:

Capsid: The protein shell of a virus.
Capsomere: Protein subunit of the capsid.
Spikes, Envelope, Tail fibers: Other viral structures, not capsid subunits.

Step-by-Step Guidance

Recall the definition and function of a capsid in viral structure.
Identify the term for the protein subunits that assemble to form the capsid.
Differentiate between capsomeres and other viral components like spikes or envelopes.

Try solving on your own before revealing the answer!

Q6. What is/are the most common method(s) used to identify viruses?

Background

Topic: Virus Identification

This question examines your understanding of laboratory techniques for identifying viruses.

Key Terms:

Serological methods: Detect viral antigens or antibodies.
Cytopathic effects: Observable changes in host cells due to viral infection.
PCR (Polymerase Chain Reaction): Amplifies viral nucleic acids.
Morphology: Physical appearance under a microscope.

Step-by-Step Guidance

Review the main laboratory methods for virus identification and their principles.
Consider which methods are most widely used in clinical and research settings.
Eliminate options that are less commonly used or less specific for virus identification.

Try solving on your own before revealing the answer!

Q7. All of the following can be used to culture animal viruses EXCEPT:

Background

Topic: Virus Cultivation

This question tests your knowledge of the systems used to grow animal viruses in the laboratory.

Key Terms:

Laboratory animals, Cell culture, Embryonated eggs: Common systems for virus cultivation.
Glucose broth: Consider if this is suitable for animal virus growth.

Step-by-Step Guidance

List the standard methods for culturing animal viruses.
Evaluate each option to determine if it supports animal virus replication.
Identify the option that is not used for this purpose.

Try solving on your own before revealing the answer!

Q8. Cell deteriorations due to viral infections are known as:

Background

Topic: Cytopathic Effects

This question is about the changes that occur in host cells as a result of viral infection.

Key Terms:

Cytopathic effect (CPE): Observable cell damage caused by viruses.
Transformation, Biosynthesis, Plaques: Other terms related to viral infection, but with different meanings.

Step-by-Step Guidance

Recall the definition of cytopathic effect and how it is observed in cell cultures.
Differentiate between cytopathic effects and other phenomena like transformation or plaque formation.
Match the correct term to the description of cell deterioration.

Try solving on your own before revealing the answer!

Q9. Continuous cell lines:

Background

Topic: Cell Culture in Virology

This question tests your understanding of the types of cell lines used for virus cultivation.

Key Terms:

Continuous cell line: Cell lines that can be maintained through many generations.
Immortal cell line: Another term for continuous cell lines.
Embryonated eggs, Bacteria: Not related to continuous cell lines.

Step-by-Step Guidance

Review the characteristics of continuous (immortal) cell lines versus primary or finite cell lines.
Identify which answer choice correctly describes continuous cell lines.
Eliminate options that do not fit the definition.

Try solving on your own before revealing the answer!

Q10. The plaque method can be used to:

Background

Topic: Virus Quantification

This question is about laboratory techniques for detecting and quantifying viruses.

Key Terms:

Plaque method: Technique to count virus particles by the clear zones (plaques) they form on a cell layer.
Bacteriophage, Animal virus, Genetic modification, Identification: Consider which is most associated with the plaque method.

Step-by-Step Guidance

Recall how the plaque method works and what type of viruses it is commonly used for.
Match the method to the correct application among the answer choices.
Eliminate options that do not directly relate to the plaque method.

Try solving on your own before revealing the answer!

Q11. Which one of the following is an example of a persistent viral infection in humans?

Background

Topic: Types of Viral Infections

This question tests your understanding of the difference between persistent and acute or latent viral infections.

Key Terms:

Persistent infection: Virus remains in the host for long periods, often with ongoing replication.
Latent infection: Virus remains dormant and can reactivate.
Acute infection: Rapid onset and resolution.

Step-by-Step Guidance

Review the definitions of persistent, latent, and acute infections.
Match each disease in the answer choices to the correct infection type.
Identify which disease is characterized by a persistent infection.

Try solving on your own before revealing the answer!

Q12. Which one of the following is an example of a latent viral infection in humans?

Background

Topic: Latency in Viral Infections

This question focuses on your ability to distinguish latent infections from other types.

Key Terms:

Latent infection: Virus remains inactive in the host and can reactivate later.
Examples: Herpesviruses are classic latent viruses.

Step-by-Step Guidance

Recall which viruses are known for establishing latency in humans.
Match each disease to its infection pattern (latent, persistent, or acute).
Identify the disease that is a classic example of a latent infection.

Try solving on your own before revealing the answer!

Q13. The enzyme that uses viral RNA as a template to produce complementary double-stranded DNA is:

Background

Topic: Viral Enzymes and Replication

This question tests your knowledge of enzymes involved in the replication of retroviruses.

Key Terms:

Reverse transcriptase: Enzyme that synthesizes DNA from an RNA template.
DNA polymerase, DNA ligase, RNA-dependent RNA polymerase: Other enzymes with different functions.

Step-by-Step Guidance

Review the replication cycle of retroviruses and the role of each enzyme listed.
Identify which enzyme is responsible for converting viral RNA into DNA.
Eliminate enzymes that do not use RNA as a template for DNA synthesis.

Try solving on your own before revealing the answer!

Q14. Viruses that infect and lyse cancer cells are called:

Background

Topic: Oncolytic Viruses

This question is about the use of viruses in cancer therapy.

Key Terms:

Oncolytic virus: Virus that selectively infects and destroys cancer cells.
Oncogenic virus: Virus that can cause cancer.
Latent, Lysogenic virus: Other types of viral relationships with host cells.

Step-by-Step Guidance

Review the definitions of oncolytic and oncogenic viruses.
Identify which term refers to viruses used to target and lyse cancer cells.
Eliminate terms that refer to viruses causing cancer or establishing latency.

Try solving on your own before revealing the answer!

Q15. Viruses capable of inducing tumors in animals are called:

Background

Topic: Oncogenic Viruses

This question tests your understanding of viruses that can cause cancer.

Key Terms:

Oncogenic virus: Virus that can induce tumor formation.
Oncolytic, Latent, Lysogenic virus: Other types of viruses with different effects.

Step-by-Step Guidance

Recall the definition of oncogenic viruses and their role in cancer development.
Match the correct term to viruses that induce tumors.
Eliminate terms that do not refer to tumor-inducing viruses.

Try solving on your own before revealing the answer!

Q16. Which part of the genome is affected by cancer-causing alterations to cellular DNA?

Background

Topic: Oncogenes and Cancer

This question is about the genetic changes that lead to cancer.

Key Terms:

Oncogene: Gene that has the potential to cause cancer when mutated or expressed at high levels.
Introns, Exons, Promoters: Other parts of the genome with different functions.

Step-by-Step Guidance

Review the definitions and roles of oncogenes, introns, exons, and promoters.
Identify which part is most commonly associated with cancer-causing mutations.
Eliminate options that are not directly linked to cancer development.

Try solving on your own before revealing the answer!

Q17. Sarcoma is a cancer of ________ tissue.

Background

Topic: Types of Cancer

This question tests your knowledge of the tissue origins of different cancers.

Key Terms:

Sarcoma: Cancer arising from connective tissues.
Nervous, Epithelial, Muscular tissue: Other tissue types where cancers can originate.

Step-by-Step Guidance

Recall the definition of sarcoma and the tissue type it originates from.
Match each tissue type to the corresponding cancer name (e.g., carcinoma, sarcoma).
Identify the correct tissue for sarcoma.

Try solving on your own before revealing the answer!

Q18. The ability of retroviruses to induce tumors is related to which enzyme?

Background

Topic: Retroviruses and Cancer

This question is about the molecular mechanisms by which retroviruses can cause cancer.

Key Terms:

Reverse transcriptase: Enzyme that synthesizes DNA from RNA in retroviruses.
RNA polymerase, DNA polymerase, Protease: Other enzymes with different functions.

Step-by-Step Guidance

Review the replication cycle of retroviruses and the role of reverse transcriptase.
Consider how integration of viral DNA into the host genome can lead to tumor formation.
Identify which enzyme is essential for this process.

Try solving on your own before revealing the answer!

Q19. Which one of the following is NOT an effect of transformation?

Background

Topic: Cellular Transformation by Viruses

This question tests your understanding of the changes that occur in cells transformed by viruses.

Key Terms:

Transformation: Process by which a normal cell becomes cancerous.
Chromosomal abnormalities, Tumor-specific antigens, Irregular shape: Common effects of transformation.
Loss of ability to divide: Consider if this is typical of transformed cells.

Step-by-Step Guidance

List the typical effects of transformation on cells.
Compare each answer choice to these effects.
Identify the option that does not fit with the others.

Try solving on your own before revealing the answer!

Q20. What percentage of cancers are known to be virus-induced?

Background

Topic: Viruses and Cancer Epidemiology

This question is about the proportion of cancers attributed to viral infections.

Key Terms:

Virus-induced cancer: Cancers caused by viral infections (e.g., HPV, HBV).

Step-by-Step Guidance

Recall the estimated percentage of cancers linked to viruses from your textbook or lecture notes.
Compare the answer choices to the commonly cited statistic.
Eliminate options that are too high or too low based on current knowledge.

Try solving on your own before revealing the answer!

Q21. A viroid is a:

Background

Topic: Subviral Agents

This question tests your understanding of the different types of infectious agents smaller than viruses.

Key Terms:

Viroid: Small, circular RNA molecule that infects plants.
Provirus, Capsid, Virus particle: Other terms related to viruses.

Step-by-Step Guidance

Recall the definition and characteristics of viroids.
Compare each answer choice to the definition of a viroid.
Eliminate options that do not match the description.

Try solving on your own before revealing the answer!

Q22. Scrapie is an example of a ________ disease found in sheep and caused by a prion.

Background

Topic: Prion Diseases

This question is about the types of diseases caused by prions.

Key Terms:

Prion: Infectious protein that causes neurodegenerative diseases.
Scrapie: Prion disease in sheep.
Neurological, Gastrointestinal, Respiratory, Cardiovascular: Types of diseases based on affected system.

Step-by-Step Guidance

Recall the symptoms and affected organ system in scrapie.
Match the disease to the correct system (e.g., nervous system).
Eliminate options that do not fit the description of prion diseases.

Try solving on your own before revealing the answer!

Q23. Prion diseases can be acquired via all of the following EXCEPT:

Background

Topic: Transmission of Prion Diseases

This question tests your knowledge of how prion diseases are transmitted.

Key Terms:

Prion transmission: Ways prion diseases can be acquired (e.g., ingestion, contaminated instruments).
Inhalation: Consider if this is a known route for prion transmission.

Step-by-Step Guidance

List the known routes of prion disease transmission.
Compare each answer choice to these routes.
Identify the option that is not a recognized route of transmission.