Q1. How are viruses classified based on shape? Give examples of icosahedral, helical, and complex viruses.

Background

Topic: Virus Morphology and Classification

This question tests your understanding of how viruses are categorized by their structural shapes and your ability to recall examples of each type.

Key Terms:

• Icosahedral: Viruses with a symmetrical, 20-sided capsid.

• Helical: Viruses with rod-shaped or filamentous capsids arranged in a helix.

• Complex: Viruses with structures that are neither purely icosahedral nor helical, often with additional features.

Step-by-Step Guidance

1. Review the definitions of icosahedral, helical, and complex viral shapes.

2. Recall the structural features that distinguish each shape (e.g., symmetry, capsid arrangement).

3. Think of at least one example virus for each shape (e.g., a common human or bacteriophage virus).

4. Consider why these structural differences might affect viral function or infection.

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Q2. What is a viral envelope? How is it formed? Give examples of enveloped and nonenveloped viruses.

Background

Topic: Viral Structure – Envelopes

This question examines your understanding of viral envelopes, their formation, and examples of viruses with and without envelopes.

Key Terms:

• Viral envelope: A lipid membrane surrounding some viruses, derived from the host cell membrane.

• Enveloped virus: Virus with an outer lipid membrane.

• Nonenveloped (naked) virus: Virus lacking an envelope, only a protein capsid.

Step-by-Step Guidance

1. Define what a viral envelope is and describe its composition.

2. Explain how the envelope is acquired during the viral life cycle (e.g., budding from host cell).

3. List at least one example each of enveloped and nonenveloped viruses.

4. Consider how the presence or absence of an envelope affects viral stability and transmission.

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Q3. What is virus host specificity (host range)? Why does it occur?

Background

Topic: Virus-Host Interactions

This question tests your understanding of why viruses infect certain hosts and not others, and the molecular basis for this specificity.

Key Terms:

• Host range: The spectrum of host species or cell types a virus can infect.

• Receptor: Molecule on host cell surface recognized by the virus.

Step-by-Step Guidance

1. Define host specificity and host range in the context of viruses.

2. Explain the role of viral attachment proteins and host cell receptors in determining host range.

3. Consider genetic and structural factors that limit or expand a virus's host range.

4. Think of examples where a virus is restricted to a single species or can infect multiple species.

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Q4. Describe the structure and lytic cycle of the T4 bacteriophage.

Background

Topic: Bacteriophage Biology

This question tests your knowledge of bacteriophage anatomy and the steps of the lytic replication cycle.

Key Terms:

• Bacteriophage: Virus that infects bacteria.

• Lytic cycle: Viral replication process resulting in host cell lysis and release of new phages.

• T4 phage: A well-studied complex bacteriophage that infects E. coli.

Step-by-Step Guidance

1. Describe the main structural components of the T4 phage (head, tail, tail fibers, etc.).

2. List the sequential steps of the lytic cycle (attachment, penetration, biosynthesis, maturation, release).

3. Explain what happens at each step, focusing on how the phage replicates and destroys the host cell.

4. Consider how the lytic cycle differs from lysogeny.

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Q5. What is lysogeny? What role does lysogeny play in the ability of a virus to reproduce?

Background

Topic: Viral Life Cycles – Lysogeny

This question examines your understanding of the lysogenic cycle and its significance in viral reproduction.

Key Terms:

• Lysogeny: Integration of viral genome into the host genome without immediate lysis.

• Prophage: Viral DNA integrated into bacterial chromosome.

• Lysogenic cycle: Alternative to the lytic cycle, allowing viral persistence.

Step-by-Step Guidance

1. Define lysogeny and describe how it differs from the lytic cycle.

2. Explain the process of viral genome integration into the host DNA.

3. Discuss how lysogeny allows the virus to persist in the host without killing it immediately.

4. Consider the triggers that can switch a lysogenic virus to the lytic cycle.

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Q6. Why is the viral replication cycle considered to have only one step?

Background

Topic: Viral Growth Curves

This question tests your understanding of how viral replication is measured and why it is described as a "one-step" process in laboratory studies.

Key Terms:

• One-step growth curve: Experimental method showing all viruses released at once after replication.

• Eclipse period: Time when no infectious virus is detected inside the cell.

Step-by-Step Guidance

1. Review what a one-step growth curve is and how it is set up experimentally.

2. Explain why all progeny viruses are released simultaneously from infected cells.

3. Describe the phases observed in the one-step growth curve (eclipse, rise, plateau).

4. Consider how this differs from cellular replication, which is continuous.

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Q7. Know the replication cycles and be able to recognize members of the following:

• a. ssDNA viruses

• b. dsDNA viruses

• c. +ssRNA viruses

• d. -ssRNA viruses

• e. retroviruses

Background

Topic: Viral Genome Types and Replication Strategies

This question tests your ability to distinguish between different viral genome types and their replication mechanisms, as well as to identify examples of each.

Key Terms:

• ssDNA: Single-stranded DNA virus

• dsDNA: Double-stranded DNA virus

• +ssRNA: Positive-sense single-stranded RNA virus

• -ssRNA: Negative-sense single-stranded RNA virus

• Retrovirus: RNA virus that uses reverse transcriptase

Step-by-Step Guidance

1. Review the replication strategy for each genome type (e.g., where and how replication occurs in the cell).

2. Recall at least one example virus for each category.

3. Understand the role of viral enzymes (e.g., reverse transcriptase in retroviruses).

4. Be able to match a virus to its genome type based on its replication features.

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Q8. What is the role of reverse transcriptase in retrovirus replication?

Background

Topic: Retroviral Replication

This question tests your understanding of the unique enzyme used by retroviruses to replicate their genomes.

Key Terms:

• Reverse transcriptase: Enzyme that synthesizes DNA from an RNA template.

• Retrovirus: Virus with an RNA genome that integrates into host DNA.

Step-by-Step Guidance

1. Define reverse transcriptase and its function.

2. Describe the steps in retrovirus replication where reverse transcriptase is used.

3. Explain why this enzyme is essential for retroviral integration and replication.

4. Consider how this process differs from other RNA viruses.

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Q9. What is the process and reason for prokaryote cell and eukaryote cell virus culture techniques?

Background

Topic: Virus Cultivation Methods

This question tests your understanding of how viruses are grown in the laboratory and why different methods are used for prokaryotic and eukaryotic viruses.

Key Terms:

• Prokaryote cell culture: Growing bacteriophages using bacterial hosts.

• Eukaryote cell culture: Growing animal or plant viruses in tissue culture or eggs.

Step-by-Step Guidance

1. Describe how bacteriophages are cultured using bacterial lawns and plaque assays.

2. Explain how animal viruses are cultured in cell lines, primary cells, or embryonated eggs.

3. Discuss why viruses require living cells for replication.

4. Consider the advantages and limitations of each method.

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Q10. Differentiate between latent and persistent viral infections and give an example of each.

Background

Topic: Types of Viral Infections

This question tests your ability to distinguish between two types of long-term viral infections and provide examples.

Key Terms:

• Latent infection: Virus remains dormant in host cells, can reactivate.

• Persistent infection: Virus continuously replicates at low levels.

Step-by-Step Guidance

1. Define latent and persistent infections, noting key differences.

2. Think of a virus that establishes latency and one that causes persistent infection.

3. Describe how each infection type affects the host over time.

4. Consider clinical implications of each infection type.

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Q11. What are cytopathogenic effects (CPEs)? Give examples of some CPE types.

Background

Topic: Viral Pathogenesis

This question tests your understanding of the visible changes viruses cause in infected cells and examples of these effects.

Key Terms:

• Cytopathogenic effect (CPE): Observable structural changes in host cells due to viral infection.

Step-by-Step Guidance

1. Define what CPEs are and how they are detected in cell cultures.

2. List common types of CPEs (e.g., cell rounding, syncytia formation).

3. Think of viruses known for causing specific CPEs.

4. Consider why CPEs are important for virus identification.

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Q12. What is the Protooncogene Theory? How does insertional inactivation contribute to oncogenesis? Give examples of oncogenic viruses.

Background

Topic: Viruses and Cancer

This question tests your understanding of how viruses can cause cancer by affecting host genes and the mechanisms involved.

Key Terms:

• Protooncogene: Normal gene that can become an oncogene due to mutation or increased expression.

• Oncogenesis: Process of tumor formation.

• Insertional inactivation: Disruption of host genes by viral genome integration.

Step-by-Step Guidance

1. Define protooncogene and explain how it can be converted to an oncogene.

2. Describe how viral integration can disrupt normal gene regulation (insertional inactivation).

3. List examples of viruses known to cause cancer in humans.

4. Consider the implications for cancer prevention and treatment.

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Q13. Define the three types of symbiotic relationships and give an example of each.

Background

Topic: Microbial Interactions

This question tests your understanding of symbiosis and your ability to provide examples relevant to microbiology.

Key Terms:

• Mutualism: Both organisms benefit.

• Commensalism: One benefits, the other is unaffected.

• Parasitism: One benefits, the other is harmed.

Step-by-Step Guidance

1. Define each type of symbiotic relationship.

2. Think of a microbiological example for each (e.g., human gut flora, pathogens).

3. Explain how each relationship affects the organisms involved.

4. Consider the ecological significance of these interactions.

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Q14. What are the two parts of the disease syndrome? Define each.

Background

Topic: Disease Terminology

This question tests your understanding of how diseases are described in terms of their observable and subjective features.

Key Terms:

• Sign: Objective, measurable evidence of disease.

• Symptom: Subjective experience reported by the patient.

Step-by-Step Guidance

1. Identify the two components of a disease syndrome.

2. Define each term and provide examples.

3. Explain why distinguishing between signs and symptoms is important in diagnosis.

4. Consider how these terms are used in clinical practice.

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Q15. Define the following terms:

• a. communicable disease

• b. contagious disease

• c. infection

• d. focal infection

• e. local infection

• f. systemic infection

• g. sepsis

• h. asymptomatic disease

• i. nosocomial infection

Background

Topic: Infectious Disease Terminology

This question tests your knowledge of key terms used to describe infectious diseases and their spread.

Key Terms:

• Communicable disease: Can be transmitted from person to person.

• Contagious disease: Easily spread from person to person.

• Infection: Invasion and multiplication of pathogens in the body.

• Focal infection: Localized infection that can spread to other areas.

• Local infection: Confined to a specific area.

• Systemic infection: Affects the entire body.

• Sepsis: Systemic inflammatory response to infection.

• Asymptomatic disease: No noticeable symptoms.

• Nosocomial infection: Acquired in a healthcare setting.

Step-by-Step Guidance

1. Define each term clearly and concisely.

2. Provide an example for at least one or two terms.

3. Note differences between similar terms (e.g., communicable vs. contagious).

4. Consider the clinical significance of each term.

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Q16. Describe what happens in the four periods of human disease.

Background

Topic: Disease Progression

This question tests your understanding of the stages of infectious disease development in humans.

Key Terms:

• Incubation period: Time between infection and symptom onset.

• Prodromal period: Early, mild symptoms.

• Period of illness: Most severe symptoms.

• Period of decline/convalescence: Symptoms subside, recovery begins.

Step-by-Step Guidance

1. List the four periods in order.

2. Define what occurs during each period.

3. Describe how symptoms change over time.

4. Consider why understanding these periods is important for disease control.

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Q17. List and define the ways disease spread throughout populations.

Background

Topic: Epidemiology – Disease Transmission

This question tests your knowledge of the main modes of disease transmission in populations.

Key Terms:

• Direct contact: Physical transfer between individuals.

• Indirect contact: Via fomites or surfaces.

• Droplet transmission: Via respiratory droplets.

• Airborne transmission: Via aerosols over distances.

• Vector-borne: Via insects or animals.

• Vehicle transmission: Via contaminated food, water, or objects.

Step-by-Step Guidance

1. List the main modes of disease transmission.

2. Define each mode and provide an example.

3. Consider how public health measures target each mode.

4. Think about which diseases are commonly spread by each route.

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Q18. Define and discriminate between incidence and prevalence with regards to the tracking of infectious diseases.

Background

Topic: Epidemiology – Disease Frequency

This question tests your understanding of how epidemiologists measure and compare disease occurrence in populations.

Key Terms:

• Incidence: Number of new cases in a specific time period.

• Prevalence: Total number of cases (new and existing) at a given time.

Step-by-Step Guidance

1. Define incidence and prevalence, noting the time frame for each.

2. Explain how each is calculated (e.g., per 1,000 or 100,000 people).

3. Describe what each measure tells us about disease spread and burden.

4. Consider why both are important for public health planning.

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