What are the key structural components of a virus?
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Understanding viral architecture, life cycle, and taxonomy of medically important viruses.
Mastering this deck will enhance your ability to identify viral structures, understand their replication strategies, and classify viruses accurately—skills essential for diagnosis, research, and developing antiviral strategies in clinical practice.
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| # | Front | Back | Hint |
|---|---|---|---|
| 1 | What are the key structural components of a virus? | Viruses generally consist of a nucleic acid genome (DNA or RNA), a protein capsid that encases the genome, and sometimes an outer lipid envelope derived from host cell membranes. | Think of a virus as a 'nucleic acid core' wrapped in a 'protein shell.' |
| 2 | What is the primary function of the viral capsid? | The capsid protects the viral nucleic acid from environmental damage and facilitates the attachment and entry into host cells. | Capsid = protective shell and key to cell entry. |
| 3 | Which viruses possess an outer lipid envelope, and how is it acquired? | Enveloped viruses acquire their lipid envelope from the host cell membrane during budding or release, examples include influenza and HIV. | Envelope = host-derived lipid layer. |
| 4 | Describe the difference between positive-sense and negative-sense RNA viruses. | Positive-sense RNA viruses have genomes that can directly serve as mRNA for protein synthesis, whereas negative-sense RNA genomes are complementary to mRNA and require transcription into positive-sense RNA before translation. | Think of positive-sense as ready-to-use mRNA; negative-sense as needing transcription first. |
| 5 | What is the Baltimore classification system? | The Baltimore system classifies viruses based on their type of nucleic acid and replication strategy, dividing them into seven groups from I to VII. | Baltimore = 'Biology of nucleic acids and replication.' |
| 6 | Name the seven Baltimore virus groups. | 1. Double-stranded DNA viruses, 2. Single-stranded DNA viruses, 3. Double-stranded RNA viruses, 4. Positive-sense single-stranded RNA viruses, 5. Negative-sense single-stranded RNA viruses, 6. Reverse-transcribing DNA viruses, 7. Reverse-transcribing RNA viruses. | Think of the groups as based on DNA/RNA type and sense. |
| 7 | What is the typical replication cycle of an obligate intracellular virus? | It involves attachment to the host cell, entry, uncoating of the viral genome, replication of nucleic acids, assembly of new virions, and release from the host cell. | Viral life cycle = attack, replicate, assemble, exit. |
| 8 | How do DNA viruses generally replicate within host cells? | DNA viruses typically replicate in the nucleus using host or viral DNA polymerases, often utilizing the host's replication machinery. | DNA = nuclear replication in most cases. |
| 9 | How do (+)ssRNA viruses differ from (-)ssRNA viruses in replication? | (+ )ssRNA viruses can directly serve as mRNA to produce proteins, while (-) ssRNA viruses must first be transcribed into (+) sense RNA by an RNA-dependent RNA polymerase. | Sense determines if the genome is ready for translation. |
| 10 | What is the significance of viral envelope glycoproteins? | Glycoproteins facilitate attachment to host cell receptors, mediating entry and determining host and tissue specificity. | Glycoproteins = keys to host cell entry. |
| 11 | Name two common receptors used by viruses for cell entry. | Examples include CD4 for HIV and sialic acid residues for influenza virus. | Receptors are like 'locks' that viruses 'key' into. |
| 12 | What are the main methods by which viruses exit host cells? | Viruses exit via cell lysis, budding (for enveloped viruses), or exocytosis. | Exit strategies include 'pop' (lysis) or 'slide out' (budding). |
| 13 | What is the purpose of viral latency, and which viruses are known for it? | Latency allows viruses to persist in host cells without active replication, enabling reactivation later; examples include herpesviruses and HIV. | Latency = viral 'sleep mode'. |
| 14 | Which viruses are classified as oncogenic, and how do they contribute to cancer? | Viruses like HPV, EBV, and Hepatitis B and C can integrate into host genomes or alter cell regulation, promoting oncogenesis. | Oncogenic viruses can turn normal cells into cancer cells. |
| 15 | What features are used to classify viruses taxonomically? | Features include genome type, replication strategy, morphology, host range, and mode of transmission. | Taxonomy = 'family resemblance' based on structure and genetics. |
| 16 | Name the family of viruses that includes herpesviruses. | Herpesviridae. | Herpesviruses are large, enveloped DNA viruses. |
| 17 | Which virus family includes the causative agent of influenza? | Orthomyxoviridae. | Orthomyxoviruses are negative-sense RNA viruses with segmented genomes. |
| 18 | What structural feature distinguishes piconaviruses (e.g., poliovirus) from other virus families? | They are small, non-enveloped, icosahedral viruses with a single-stranded positive-sense RNA genome. | Small, simple, and non-enveloped. |
| 19 | Explain the concept of viral tropism. | Viral tropism refers to the preference of a virus for specific cell types or tissues, determined by receptor availability and cellular factors. | Tropism = 'viral target preference.' |
| 20 | How do antiviral drugs typically interfere with viral replication? | They target specific stages such as entry, uncoating, nucleic acid synthesis, or assembly, e.g., reverse transcriptase inhibitors or protease inhibitors. | Target the viral 'assembly line.' |
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